New Scientist Magazine - 17th January 2009

New Science Publications Editor-in-Chief Jeremy Webb

Editorial–

Editor Roger Highfield Associate Editors Liz Else, Stephanie Pain News Editor Shaoni Bhattacharya Editors Helen Knight, Celeste Biever, Richard Fisher, Sumit Paul-Choudhury, Priya Shetty Tel +44 (0) 20 7611 1206 Fax +44 (0) 20 7611 1250 Reporters LONDON Andy Coghlan, Paul Marks, Linda Geddes, David Shiga [email protected] BOSTON US Bureau Chief Ivan Semeniuk SAN FRANCISCO Bureau Chief Peter Aldhous [email protected] Jim Giles [email protected] TORONTO Alison Motluk BRUSSELS Debora MacKenzie MELBOURNE Australasian Editor Rachel Nowak [email protected] Features Editors Ben Crystall, Kate Douglas, Clare Wilson, David Cohen, Graham Lawton, Valerie Jamieson, Michael Le Page, Caroline Williams, Richard Webb Features Contacts Tel +44 (0) 20 7611 1201 Fax +44 (0) 20 7611 1280 [email protected] Opinion Editor Jo Marchant Editors John Hoyland, Amanda Gefter, Alison George, Eleanor Harris Tel +44 (0) 20 7611 1240 Fax +44 (0) 20 7611 1280 [email protected] Researcher Lucy Dodwell Editorial Assistant Amy Galloway Production Editor Mick O’Hare Asst Production Editor Melanie Green Chief Sub John Liebmann Subeditors Vivienne Greig, Julia Brown, Sean O’Neill, Eleanor Parsons Art Director Alison Lawn Design Craig Mackie, Ryan Wills Graphics Nigel Hawtin, Dave Johnston Pictures Adam Goff, Kirstin Jennings Tel +44 (0) 20 7611 1268 Fax +44 (0) 20 7611 1250 Careers Editor Helen Thomson [email protected] Tel +44 (0) 20 7611 1248 Fax +44 (0) 20 7611 1280 Consultants Alun Anderson, Anil Ananthaswamy, Stephen Battersby, Michael Bond, Michael Brooks, Marcus Chown, Rob Edwards, Richard Fifield, Barry Fox, Mick Hamer, Jeff Hecht, Bob Holmes, Justin Mullins, Fred Pearce, Helen Phillips, Ian Stewart, Gail Vines, Gabrielle Walker, Emma Young Press Office and Syndication UK Claire Bowles Tel +44 (0) 20 7611 1210 Fax 7611 1250 US Office Tel +1 617 386 2190 NEWSCIENTIST.COM Online Publisher John MacFarlane Online Editor Rowan Hooper Editors Maggie McKee, Tom Simonite Reporters Catherine Brahic, Colin Barras, Sandrine Ceurstemont, Michael Marshall, Ewen Callaway, Rachel Courtland Online Subeditor Dan Palmer Web team Neela Das, Cathy Tollet, Ruth Turner, Ken Wolf, Edin Hodzic, Vivienne Griffith, Rohan Creasey, Matteo Giaccone

What were they thinking? Neuroscience could learn much from the humility of Charles Darwin IT IS two centuries since the birth of Charles Darwin, but even now his advice can be spot on. The great man attempted a little neuroscience in The Expressions of the Emotions in Man and Animals, published in 1872, in which he discussed the link between facial expressions and the brain. “Our present subject is very obscure,” Darwin warned in his book, “and it is always advisable to perceive clearly our ignorance.” Modern-day neuroscience might benefit from adopting a similar stance. The field has produced some wonderful science, including endless technicolor images of the brain at work and headline-grabbing papers about the areas that “light up” when registering emotions. Researchers charted those sad spots that winked on in women mourning the end of a relationship, the areas that got fired up when thinking about infidelity, or those that surged in arachnophobes when they thought they were about to see a spider. The subjective subject of feelings seemed

Stem cell bonanza DESPITE progress ranging from bone marrow transplants to reconstructed windpipes, it is still easy to forget that many stem cell treatments are still some way off. Which is why a new discovery gives us grounds for optimism (see page 6). If it works as well in humans as it has in mice, it should enable patients to produce floods of potentially curative stem cells in their own bone marrow. All it takes is a drug called Mozobil, plus a natural growth factor, to boost production of stem cells with the potential to repair blood, muscle, bone, ligaments and blood vessels.

The method would use a person’s own stem cells, so there is no need to tinker with cells outside the body, nor any possibility of rejection. To fix other kinds of tissue we will still need the most versatile of stem cells, the embryonic kind. The good news is that Mozobil and the growth factor are all already commercially available, making it easier to do further animal experiments and human trials. Best of all, we can take heart that dazzling advances genuinely promise new treatments, and don’t just swell the academic literature. ●

Reasons to be cheerful ACCORDING to a deeply unscientific but oft-quoted formula, 19 January will be “blue Monday”, the most miserable day of the year. That is the day when we are supposedly most likely to wallow in self-pity, feeling fat, broke and washed-up. The credit crisis and consequent global economic woes have, it’s true, made the start

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at last to be becoming objective. Now it seems that a good chunk of the papers in this field contain exaggerated claims, according to an analysis which suggests that “voodoo correlations” often inflate the link between brain areas and particular behaviours (see page 11). Some of the resulting headlines appeared in New Scientist, so we have to eat a little humble pie and resolve that next time a sexysounding brain scan result appears we will strive to apply a little more scepticism to our coverage. Neuroscientists should also take a hard look at their techniques, but don’t expect anyone to rush back to reanalyse the data. Science is too competitive to spend time raking over old results. This is not the first time neuroscientists have been criticised for over-egging brain scanner results (New Scientist, 21 September 2002, p 38). It probably won’t be the last. But at least there are signs that the self-correcting nature of science will win the day. ●

of this year feel particularly depressing for many. But consider this: it turns out that being too happy can actually be bad for you (see page 36), leaving you unwilling to make the effort to change your life for the better. So why not stop being miserable about being miserable, and start to enjoy it for a change? Just don’t smile and wreck all the benefits. ● 17 January 2009 | NewScientist | 3

News in perspective

Upfront– ROB ATKINS/GETTY

THREATENED BY AN ANGRY SUN Our technologically dependent society could be brought to its knees the next time Earth is walloped by an extreme solar outburst. Intense outbursts of plasma from the sun, called coronal mass ejections, can create electromagnetic interference that plays havoc with technology. In 1989, one nasty blast knocked out the power grid in Quebec, Canada, for several hours. Future blasts could be much worse, according to a report by a US National Research Council committee led by Daniel Baker of the University of Colorado in Boulder, based on workshops held last year. The most powerful solar outburst on record happened in 1859. Then, it merely disrupted telegraph communication. If it happened today, it could cause lasting damage to power grids, with knock-on

effects on supplies of water, medicine and other necessities, the report says. Damaged transformers could be a particularly big problem. “If a large number were taken out it could take quite a while to replace them,” says Baker. “There’s not a lot of stock… and they have to be built to order.” Fortunately, there are ways to reduce the risk of catastrophe. Relatively cheap modifications could make transformer circuits up to 70 per cent less vulnerable to solar storm damage, the report says. One small mercy is that some scientists argue the sun is likely to enter a decades-long quieter period soon, during which big outbursts would be less likely (New Scientist, 10 January, p 11). However, this prediction is fraught with uncertainty.

Drug safety fears

30 to 74 (The New England Journal of Medicine, vol 360, p 231). Ray believes a perception that these drugs are safe has led to them being prescribed more. Meanwhile Clive Ballard at King’s College London and his colleagues have completed the first long-term study of the effect of antipsychotics on people with Alzheimer’s, who are given the drugs to reduce aggression and agitation. They found that prolonged use increases the risk of premature death, and recommend antipsychotics only as a last resort in people with Alzheimer’s (The Lancet Neurology, DOI: 10.1016/ S1474-4422(08)70295-3).

–Technology in the firing line–

THE rabbit population boom ravaging Macquarie Island, halfway between Australia and Antarctica, is providing an urgent reminder of why conservationists need to analyse all aspects of an eradication programme. A plan to save the island’s birds by ridding it of its 160 feral cats has gone disastrously wrong, with the rabbit population now at a whopping 130,000, up from just 4000 in 2000. Clearing up the world heritage site is expected to cost AU$24 million (US$16 million). “We need a culture change,” says ecologist Hugh Possingham of the University of Queensland in Brisbane. Environmentalists “are often averse to maths, and so avoid quantitative risk assessments”, he says.

“The rabbit population is now at a whopping 130,000, up from just 4000 in 2000” The rabbits have trashed the vegetation on 40 per cent of the island, according to an estimate by Dana Bergstrom of the Australian Antarctic Division in Tasmania and colleagues (Journal 4 | NewScientist | 17 January 2009

of Applied Ecology, vol 46, p 73). The Tasmanian Parks and Wildlife Service (TPWS), which eradicated the last cat in 2000, expected myxomatosis to limit rabbit numbers. But Bergstrom believes that had the TPWS “done their calculations” it could have avoided a population explosion. A spokesperson for TPWS, however, told New Scientist that it was a “conservation achievement” to remove one of the island’s main pests. It is now planning a rabbit and rodent eradication programme for next year. This time, TPWS says, it intends to conduct a quantitative risk assessment first. JANET JARMAN/CORBIS

Runaway rabbits

FRESH fears have been raised over the safety of antipsychotic drugs. First-generation antipsychotics, which are mainly used to treat schizophrenia, mania or delusion disorder, are known to raise the risk of heart problems. Now Wayne Ray at Vanderbilt University in Nashville, Tennessee, and colleagues report that newer antipsychotics such as olanzapine, risperidone and quetiapine, which were thought to be safer than their older counterparts, also pose risks. The researchers found these drugs double the risk of sudden cardiac death among people aged

Tequila hangover THE benefits of a good name only stretch so far. A “geographical indication” (GI) that legally ties products like champagne and tequila to their place of origin and cultural heritage does not always help the region it sets out to protect. Sarah Bowen of North Carolina State University in Raleigh and her colleagues found that tying the making of tequila to the Jalisco region of Mexico has –Agave blues– made its production socially www.newscientist.com

60 SECONDS and ecologically unsustainable. Tequila’s blue agave plant takes six years to mature, leading to an unstable local supply. This, plus a huge leap in demand for the drink since the 1990s, has driven many liquor companies to grow their own near Jalisco (Journal of Rural Studies, DOI: 10.1016/ j.jrurstud.2008.07.003). This has led to “environmental degradation and the elimination of traditional practices”, says Bowen. Tequila – the first GI granted outside Europe – should be a lesson to other poor nations, says Bowen. “The specification of sustainable production practices within [the GI] legal framework is essential,” she says.

Epidural safety

Watchdog’s woes

IRON-SEEDING SHIP SETS SAIL

NASA’s financial watchdog is a toothless organisation that does Legal controversy surrounds the not understand the role of an largest ever “iron-seeding” experiment auditor. That is the scathing to geoengineer the climate as it sets conclusion of a report from the sail from South Africa. US Government Accountability Within weeks, a team led by Victor Office (GAO). Smetacek of the Alfred Wegner Institute NASA’s Office of the Inspector in Bremerhaven, Germany, hopes to General (OIG) is charged with dump 20 tonnes of ferrous sulphate into improving the space agency’s the Southern Ocean. The aim is to trigger efficiency while also identifying a plankton bloom that will suck carbon any mismanagement or abuse out of the air and lock it up at the of its $17 billion annual budget. bottom of the ocean. Yet out of the 71 NASA programme After a company called Planktos audits carried out between 2006 sparked controversy in 2007 with plans and 2007, only one identified to dump iron filings in the Galapagos, any potential cost savings, claims both the International Maritime the GAO report. This makes Organization (IMO) and the UN NASA’s inspectorate poor value Convention on Biological Diversity for money, say the authors, who recommended that governments restrict calculate that the OIG recoups only such activities because they could have 36 cents for every dollar it costs to run, compared with an average of $9.49 for those overseeing other US agencies. Most of the blame is directed at Robert Cobb, head of the OIG, for choosing investigations not intended to save money. He counters that the GAO report is flawed because it uses “selective and incomplete data”. Politicians may have had enough, however. Bart Gordon, chairman of the US House Committee on Science and Technology, wants Barack Obama’s administration to remove Cobb from his post. –Blooming disaster?– www.newscientist.com

The US government spent $52.4 billion on nuclear weapons in 2008, according to US think tank the Carnegie Foundation. This is twice the total spend on science, space and technology, and 14 times the budget for energy research. While $47 billion goes towards maintaining the US arsenal, only $5 billion is spent on preventing nuclear threats.

“Past results were variable, which has been confusing for anaesthetists and patients”

Brown revolution begins

320,000 and 1 in 80,000. “Past results have been very variable, which has been confusing for anaesthetists and made it difficult for them to communicate the risk to patients,” says Cook.

African scientists this week began a project to boost food production by compiling a digital map of the continent’s horrendously depleted soils. Launched by the International Center for Tropical Agriculture in Nairobi, Kenya, the map will show which compounds – such as phosphate – are needed where to restore soil fertility.

Telescope marathon

detrimental effects on ecosystems. The IMO’s rules on marine protection do not cover experiments like Smetacek’s, but “it will be in clear defiance of the UN Convention on Biological Diversity”, warns Jim Thomas of environmental research organisation ETC Group. Smetacek says his expedition has been approved by the German government, which helped define the UN guidelines. Others point out the experiment is unlikely to cause harm. “Twenty tonnes of iron particles in the vast ocean is very much a drop in the bucket,” says Ken Caldeira of the Carnegie Institution at Stanford University in California. “The rational concern is that experiments will lead down some slippery slope – that small experiments could be scaled up without any regulation.”

Astronomers looked set to break records this week by monitoring three quasars for 33 hours – the longest time this has been achieved “live”. On 15 and 16 January, telescopes from Asia, Australia, Europe and the Americas were due to stream data via high-speed fibre links directly to a supercomputer – creating the biggest real-time telescope ever.

Goats against clots

JACQUES DES CLOITRES/MODIS/GSFC NASA

WOMEN in pain during childbirth now have one less thing to worry about. The most comprehensive study into the risks posed by epidurals concludes that they are safer than previously thought. Estimates of the risk of lasting harm from these spinal injections, often offered to women in labour to numb the pain of childbirth, vary quite a bit, but a figure used widely was 1 in 25,000. Now a panel led by Tim Cook of the Royal United Hospital in Bath, UK, has collected information from all National Health Service hospitals in the UK that carry out the procedure. It concludes that

Nuclear budget explodes

the chance of lasting harm from a spinal anaesthetic is between 1 in 50,000 and 1 in 23,000 (British Journal of Anaesthesia, DOI: 10.1093/bja/aen360). If only women in childbirth are considered, it is between 1 in

A drug expressed in the milk of genetically engineered goats has won a favourable review from the US Food and Drug Administration. Made by GTC Biopharmaceuticals of Rockville, Maryland, antithrombin prevents blood clots during surgery or childbirth in people with a rare clotting disorder. It received European approval in 2006.

Cancer-free baby? The first baby to be screened as an embryo for the presence of a gene that raises the risk of cancer has been born. Paul Serhal’s team at University College London discarded six embryos with the BRCA1 gene, which raises the risk of breast cancer by 80 per cent, and implanted two lacking it, resulting in one birth.

17 January 2009 | NewScientist | 5

International news and exclusives

This Thisweek– week–

Heal yourself, with stem cells’ help Drugs that free up the body’s own stem cells could bring simpler, cheaper therapies a step closer ANDY COGHLAN

IT HAS been an uplifting week for stem cell research. Not only is US president-elect Barack Obama poised to sweep away restrictions on stem cells when he takes office on 20 January, but a new treatment based on the drug Mozobil promises to harness an individual’s stem cells to help them heal their own bodies. A few days ago Sara Rankin and her colleagues at Imperial College London announced that Mozobil, in combination with natural growth factors, can free up specific types of stem cells from the bone marrows of mice and send them flooding into the bloodstream. The discovery is important because it opens up the possibility of treatments tailored to the individual, who would for example take drugs to stimulate the growth and release of specific stem cells to repair cardiac tissue after a heart attack. Such treatments would be free of the ethical baggage associated with therapies based on extracting stem cells from human embryos – though their development would not remove the need for embryonic stem cell research as they do not cover all cell types. Treatments to stimulate the bone marrow to make stem cells are already widely used to treat leukaemias and other blood cancers. Based on a natural growth factor called granulocyte colony stimulating factor (GCSF), they prompt the bone marrow to produce extra haematopoietic stem cells (HSCs), which grow into all types of blood cell. These cells can be extracted over weeks and 6 | NewScientist | 17 January 2009

stored ready for transplant into the bone marrow following chemotherapy to kill cancerous blood cells, where they restock the blood cells destroyed by the anti-cancer drugs. Now Rankin’s team has shown that it is possible to persuade the bone marrows of mice to produce two additional categories of stem cell – mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) – broadening considerably the types of damage and disease that might be treatable. “It’s promoting self-healing,” says Rankin, whose team’s research –Broken bones could mend faster – was published last week in down inflammation, and so could Cell Stem Cell (DOI: 10.1016/j. stem.2008.10.017). “We’re simply be used to treat autoimmune diseases. EPCs repair blood vessels boosting what’s going on and form new ones, so they have naturally, and we’ve shown that the potential to restore vital blood we can selectively mobilise supplies to tissues damaged by different types of stem cell.” strokes or heart attacks. MSCs grow into muscle and Rankin and her colleagues bone, and so have the potential showed that they could persuade to repair cardiac tissue following mouse bone marrow to release heart attacks, or to accelerate floods of both types of cell at the healing of broken bones or same time by giving the mice ligaments. They also damp

STEM CELL DELIVERANCE IS NIGH After Barack Obama is inaugurated as US president on 20 January, expect him to make good on his promise back in August to reverse George W. Bush’s restrictions on stem cell research. “As president, I will lift the current administration’s ban on federal funding of research on embryonic stem cell lines created after 9 August 2001 through executive order,” he said. Now the smart money is on him issuing an executive order himself within days to get rid of the veto that

Bush introduced to satisfy opponents of research on human embryos. Congress may later pass legislation to block reintroduction of the restrictions by future administrations. In a memo to the transition team this week, the US Center for Genetics and Society in Oakland, California, called on Obama to work with Congress to introduce comprehensive laws overseeing all stem cell research in the US, which at present is completely unregulated in the private sector.

Mozobil plus a natural substance called vascular endothelial growth factor (VEGF). Rankin’s team also used GSCF and Mozobil in mice to show that, in principle, drug therapies can be tweaked to produce either blood stem cells or those that become muscle, bone and blood vessels. What is more, the stage is set for these treatments to be tried in people, as both growth factors are available commercially. Mozobil’s maker, Genzyme of Cambridge, Massachusetts, received approval in December from the US Food and Drug Administration to sell the drug in combination with GCSF for treating lymphoma. Genzyme told New Scientist that it is looking into other ways of using Mozobil. “Its novel mechanism of action opens the door for a rich area of research,” says Richard Peters, vice-president of global medical affairs at Genzyme Transplant and Oncology. One big question is whether www.newscientist.com

In this section

ethical and regulatory issues associated with other types of stem cell therapy, and it would be a lot cheaper,” says Rankin. But she stresses that the approach can’t be used for every type of disease, and so should not be used by governments as a reason to reduce funding for other stem cell research. She points out, for example, that there are no known bone marrow stem cells that make nerve or brain cells. These can only be made from embryonic stem cells, or from induced pluripotent stem cells produced by introducing genes that coax skin and other cells back into an embryonic-like state. Robin Lovell-Badge of the UK’s National Institute for Medical Research in London agrees. “It doesn’t change the need to do embryonic stem cell research at all.” Bone marrow stem cells, for example, can’t make insulinproducing islet cells for treating diabetes, he adds. What Rankin hasn’t shown yet, as she herself admits, is whether the stem cells produced in her study do indeed accelerate or the new approach will supplant improve healing. And as Lovellor simplify other stem cell Badge points out, “Giving patients treatments in development. Mozobil plus VEGF could have Many of these rely on extraction other effects on the body.” and multiplication of specific Tantalisingly, however, there is stem cells from patients’ blood, unpublished evidence that a process which takes weeks and Mozobil-derived EPCs help heal is technically difficult. Given cardiac tissue in mice after heart Mozobil plus growth factors, attacks. The research, presented patients could potentially make in 2003 at the American Heart extra copies of the same cells Association’s annual meeting, was in their own bodies. led by Atsuchi Iwakura and his colleagues at AnorMed, the “We’re simply boosting what’s in Boston which going on naturally, and we can company originally developed Mozobil. The selectively mobilise different results show that the hearts of types of stem cell” treated mice recovered faster and had less scarring a month after the heart attack. An international registry of Rankin favours further clinical trials run by the US research in animals before National Institutes of Health included 720 new or ongoing trials moving into people, but she which specified enriching patients’ acknowledges that all the ingredients are available own stem cells outside the body commercially, and so could be as part of the treatment. In many used by anyone contemplating cases the new drug regime could clinical trials. “It’s feasible this potentially be used instead. will happen in the next five to 10 “Ours is a much more direct years,” she says ● approach, and doesn’t have the www.newscientist.com

Warmer climate stifles poor nations’ economies GlOBAL warming will not only devastate agriculture in developing countries, it will undermine economic and political stability to a far greater extent than previously imagined, according to new study. The link between “high temperatures and poor growth is much stronger than we’d realised”, says Benjamin Olken, an economist at the Massachusetts Institute of Technology. Crucially, says Olken, his team’s study is the first to link climate change with economic growth – as opposed to output – which will have a bigger long-term effect on a country’s fortunes. High temperatures could even undermine scientific productivity, say Olken’s team. If they are correct, the economic gulf between rich and poor nations will widen dramatically this century. The team looked at how temperatures affected economic growth in the past 50 years. While rich economies seemed resilient to temperature rises, the GDP of poor countries dropped by 1 per cent in years when those temperatures rose 1 °C or more above the regional average. The number of scientific papers – a measure of innovation – also fell in poor countries in hot years, as did economic investment in the region. Breakdown in government was more

likely, as were political coups. Olken says his results fit with other studies showing that high temperatures increase civil unrest, and that drought can lead to political instability. The results were presented last week at a meeting of the American Economics Association, in San Francisco. Slowing growth rates would have cumulative effects that studies might miss if they were only focusing on specific issues such as the impact of drought on food supply, he says. If global temperatures rise as predicted, the economic gap between rich and poor nations will have doubled a decade from now. In 50 years’ time the gap will have widened 12-fold. The study’s breadth and emphasis on growth is welcome but the results need to be treated with caution, economist Eric Strobl of the École Polytechnique in Paris, France, told New Scientist. He points out that Olken failed to find a link between rainfall and economic growth that previous work on agriculture suggests should exist. Richard Tol of the Economic and Social Research Institute in Dublin, Ireland, adds that poor nations often suffer from corruption, a factor that Olken’s analysis did not explicitly control for. Jim Giles ● AMI VITALE/PANOS

DAVID BABCOCK/ALT-6/ALAMY

● ‘Phoenix’ universe, page 8 ● Novels act as societal glue, page 10 ● Doubt over brain image results, page 11

–No way to grow when the heat is on– 17 January 2009 | NewScientist | 7

This week–

SOUNDBITES

Dark energy gave us our home JESSICA GRIGGS

OUR universe may have arisen from seeds preserved in a universe that existed before the big bang – all thanks to dark energy. One of the models put forward to explain how the universe began proposes that it is just the latest phase in a never-ending cycle. Proposed in 2002 by Paul Steinhardt of Princeton University and Neil Turok from the University of Cambridge, the model argues that our universe exists on a 3D region called a “brane” separated from similar branes by a fourth spatial dimension. Under the right conditions, these branes collide, triggering a big-bang-like event. After the collision, the branes bounce apart, before another collision occurs many billions of years later. This model initially struggled to explain the ripples in the temperature and density of the universe that can be seen in the cosmic microwave background radiation left over from the big bang. The only way to make calculations based on the cyclic model produce the observed pattern of ripples is to add extra dimensions, as predicted by string theory, on top of the four

spatial dimensions that the initial scenario envisaged. Unfortunately, adding extra dimensions throws up another problem. As two branes approach, the additional dimensions must shrink or grow in sync with the dimension that separates the branes. Otherwise, large areas of the brane become warped, so that most of it ends up as black holes and only a tiny proportion as ordinary, habitable space. After several cycles, this space shrinks to

“Without dark energy, most of the brane would end up as black holes, leaving only a tiny proportion as habitable space” nothing, so the process is unlikely to have led to our universe. Now calculations by Steinhardt and Jean-Luc Lehners, also at Princeton, show that when dark energy – the stuff that appears to be causing the expansion of the universe to accelerate – is brought into the picture, the cycling can be sustainable, so long as dark energy dominates for around 600 billion years. In earlier cyclic models, dark energy has merely kept the cycles stable, and only dominated for the

first 10 billion years or so. The pair say their calculations show that dark energy may in fact last much longer, and so is “absolutely essential” for the endurance of habitable regions. After each clash it would stretch the habitable regions so there is enough left after the next clash, and so on in subsequent cycles (see diagram). “Most of the universe is consumed in ashes, but the phoenix universe emerges once again from the small surviving seed,” says Steinhardt (www.arxiv.org/abs/0812.3388). This is not the first use of the term “phoenix universe”. It was coined in 1933 by Georges Lemaître, an advocate of the big bang theory. “Our model is a more appropriate use of the name,” Steinhardt claims. “We were motivated by the same conceptual issue: what happened at the big bang. Was it the beginning or not?” Like its predecessors, the pair’s work is built on a variant of string theory called M-theory which has yet to be completely fleshed out, says Peter Coles of the University of Cardiff in the UK. Andrew Liddle of the University of Sussex, UK, describes their model as a “neat and novel” picture, but adds that it is “hard to believe that we’ll ever make observations that could show whether it is right or not”. However, Martin Bojowald of Pennsylvania State University, University Park, says their model is “more realistic” than previous versions, and that future measurements of dark energy may allow the idea to be tested. ●

COSMIC RECYCLING In one model of how the universe began, dark energy lasting hundreds of billions of years is an essential ingredient As branes collide...

...only a fraction of the habitable areas survive to seed the new universe

SEED HABITABLE REGIONS

...but thanks to dark energy the seeds expand enough for the cycle to repeat

‹ I guess I could have been popular by accepting Kyoto.› In his final press conference, President George W. Bush said he could easily have won popularity in Europe, if he had wanted to, by agreeing to international initiatives such as the Kyoto protocol (The Guardian, London, 13 January)

‹ He’s not a genius. They had no passwords, no firewalls, and that’s the problem – Gary embarrassed them.› Janis Sharp defends her son Gary McKinnon, who faces extradition to the US with a possible 70-year sentence for hacking into NASA computers, apparently to search for evidence of extraterrestrial life (The Times, London, 13 January)

‹ Fetal testosterone not only masculinises the body, it masculinises the mind.› Autism researcher Simon Baron Cohen from the University of Cambridge on his finding that children exposed to high levels of testosterone in the womb have a greater risk of developing autism-spectrum characteristics, which he believes are more “male” (AFP, 12 January)

‹ We can’t fire our bears or furlough our sea lions.› Many US zoos and aquariums are losing government funding as a result of the financial crisis, but John Calvelli of the Wildlife Conservation Society, which operates zoos and aquariums in New York, points out that it’s hard to see where cuts can be made (Associated Press, 13 January)

‹ We applaud the folks at City Crab and Seafood for their compassionate decision.› Ingrid Newkirk, president of PETA, responding to the news that George, a lobster thought to be as old as 140 – an age rarely seen in captivity – has been returned to the ocean from his previous home, a New York restaurant (Reuters, 9 January)

COLLAPSED BLACK HOLES

8 | NewScientist | 17 January 2009

www.newscientist.com

M.DEUTSCH/CORBIS

Model of surprise has ‘wow’ factor built in WE ALL know what surprise feels like, but a computer model has now defined the concept. It is the change in expectation caused by the arrival of new data, it says. The model uses an aptly named unit of measurement – the “wow”. Pierre Baldi at the University of California, Irvine, and Laurent Itti at the University of Southern California in Los Angeles devised the model while investigating human attention. A dominant theory from the 1950s has it that the amount of attention we pay to an object or event is linked to the volume of information our brains need to form an understanding of it. For example, our attention should hover over intricate patterns longer than over a plain surface. But this model did not consider that the majority of data is useless, says Itti, while only a little is of interest to you or might indicate a threat. Instead, he and Baldi reckon that we focus more on objects or movements that attract our

attention by being surprising or unexpected. Surprise as they compute it may also explain what causes the “orienting reflex”, whereby our attention is caught by novel stimuli. To test their hypothesis, the pair developed a computer model which simulated a population of visual neurons “watching” video clips, just as your brain would watch it through the eye’s retina. They used the model to analyse short video clips and mark which regions of the videos it considered the most surprising – which they rated in wows. “Something that is very surprising has a high wow content,” says Baldi. When they showed the videos to human volunteers, their eye movements correlated with what the computer had rated as being worthy of attention. “We found that human observers did indeed look at surprising things while watching TV, much more than they looked at information-rich objects,” says

Self-replicator suggests life began with RNA

to DNA. One of the reasons for this is that, unlike DNA, RNA molecules can catalyse chemical reactions. “We’re trying to jump in at the last signpost we have back there in the early history of life,” Joyce says. Joyce and Lincoln created their RNA enzyme, or ribozyme, called R3C, from scratch to perform a single function: stitching two shorter RNAs together to create a clone of itself. Next, Lincoln redesigned R3C, making a sister RNA that could itself join two RNAs into a ribozyme. Rather than replicating themselves, each molecule was able to make a copy of its sister, a process called cross replication. The pairs double until there are no more starting bits of RNA left. “We just let them amplify themselves silly,” says Joyce. The team then sought to “evolve” their molecule. They added different

A SYNTHETIC molecule that performs an essential function of life – selfreplication – could shed light on the origin of all living things. The lab-born strand of ribonucleic acid (RNA) can evolve in a test tube to double itself ever more swiftly. This is the first time that an experiment has produced an RNA that can sustain its own replication. Gerald Joyce, a biochemist at the Scripps Research Institute in La Jolla, California, and colleague Tracey Lincoln studied RNA because most researchers think early life stored information in this sister molecule www.newscientist.com

–Simulated surprise–

Itti (Vision Research, DOI: 10.1016/ j.visres.2008.09.007). This study is a long-awaited “satisfactory theoretical account” for what holds our attention, says Aapo Hyvärinen, a computer scientist at the University of Helsinki in Finland. He adds that it formulates “a Bayesian theory of surprise in which an event is surprising if it changes our beliefs”. Itti says the model could have wide-ranging applications. For

example, it could be used to rank websites for interest, as those providing more original content would stand out, while spammers, copycats and aggregator sites may be classified as boring. It could also be used to design more eyecatching advertisements, he says. He and Baldi are now carrying out experiments in monkeys to see if individual retinal neurons compute surprise in the way their model predicts. Linda Geddes ●

versions of R3C ribozyme pairs to test tubes containing a wider range of RNA building blocks. Giving the ribozyme pairs an array of components meant they could concoct new ribozymes. Since each enzyme has slightly different properties, these new forms might be better or worse at replicating their sister ribozyme. What came out bore an eerie resemblance to natural selection: a few sequences proved to be winners, but most lost out (Science, DOI: 10.1126/ science.1167856). The victors emerged because they could replicate faster in the face of competition, Joyce says. “I wouldn’t call these molecules

alive,” he cautions, since life is not simply the ability to replicate like crazy. The molecules must also gain new functions without laboratory tinkering – something that Joyce says he has no idea how to create yet. A life-mimicking molecule will also need to assemble itself from simpler components than two halves, says Michael Robertson, a biochemist at the University of California, Santa Cruz. DNA and RNA normally replicate with the help of a protein enzyme that joins individual nucleotide “letters” together. Early life may have had an enzyme that did the same, or this enzyme could have joined short stretches of RNA, Robertson says. The true story of the origin of life will always remain elusive, however. “[It] is a historical problem that we’re never going to be able to verify,” Robertson says. Ewen Callaway ●

“A few RNA sequences proved to be winners. These were the ones that could replicate faster in the face of competition”

17 January 2009 | NewScientist | 9

This week–

Novels help to uphold social order PRIYA SHETTY

WHY does storytelling endure across time and cultures? Perhaps the answer lies in our evolutionary roots. A study of the way that people respond to Victorian literature hints that novels act as a social glue, reinforcing the types of behaviour that benefit society. Literature “could continually condition society so that we fight against base impulses and work in a cooperative way”, says Jonathan Gottschall of Washington and Jefferson College, Pennsylvania. Gottschall and co-author Joseph Carroll at the University of Missouri, St Louis, study how Darwin’s theories of evolution apply to literature. Along with John Johnson, an evolutionary psychologist at Pennsylvania State University in DuBois, the researchers asked 500 people to fill in a questionnaire about 200 classic Victorian novels. The respondents were asked to define characters as protagonists or

10 | NewScientist | 17 January 2009

AIP/RONALD GRANT ARCHIVE

antagonists, and then to describe their personality and motives, such as whether they were conscientious or power-hungry. The team found that the characters fell into groups that mirrored the egalitarian dynamics of hunter-gather society, in which individual dominance is suppressed for the greater good (Evolutionary Psychology, vol 4, p 716). Protagonists, such as Elizabeth Bennett in Jane Austen’s Pride and Prejudice, for example, scored highly on conscientiousness and nurturing, while antagonists like

Starving bacteria bumped up early Earth’s oxygen

HUNGRY nickel-grabbing bacteria could be to thank for the surge in atmospheric oxygen 2.5 billion years ago that made Earth hospitable to life. Stefan Lalonde of the University of Alberta in Edmonton, Canada, and colleagues measured the concentration of nickel deposited in layered sedimentary rocks, or “banded iron formations”. They found that levels had dropped by twothirds in the 200 million years prior to the “Great Oxygenation Event”. The team speculate that this drop in nickel starved primordial ocean-dwelling bacteria called methanogens that used dissolved nickel in seawater to help turn food into energy and methane. As methane reacts with oxygen to remove it from the atmosphere, a decline in the methane produced by bacteria would have led to a build-up of oxygen. Though it is not clear quite how much the ancient bacteria relied on the metal, “growing modern methanogens in the lab requires extremely high concentrations of nickel”, says Stephen Zinder at Cornell University in Ithaca, New York. So what could have caused the nickel shortage? A surge in the number of magma plumes just before the nickel decline removed a large amount of heat from Earth’s core, say the team. In these cooler conditions, more oceanic crust was created relative to continental crust. This contains less of the nickel that the bacteria can use. The work was presented at the American Geophysical Union meeting in December. “This study is one of the first to look at hard data about metal concentrations, which is an important new idea,” says Timothy Lyons of the University of California, Riverside. But he suspects the oxygenation effect may be less than the team thinks, because the bacterial famine could have enabled other atmospheric reactions that –Heathcliff’s personality reflects societal pressures– used up oxygen. Devin Powell ●

Bram Stoker’s Count Dracula scored highly on status-seeking and social dominance. In the novels, dominant behaviour is “powerfully stigmatised”, says Gottschall. “Bad guys and girls are just dominance machines; they are obsessed with getting ahead, they rarely have pro-social behaviours.” While few in today’s world live in hunter-gatherer societies, “the political dynamic at work in these novels, the basic opposition between communitarianism and dominance behaviour, is a universal theme”, says Carroll. Christopher Boehm, a cultural anthropologist whose work Carroll acknowledges was an important influence on the study,

“The characters in the novels fell into groups that mirrored the egalitarian dynamics of hunter-gatherer society”

agrees. “Modern democracies, with their formal checks and balances, are carrying forward an egalitarian ideal.” A few characters were judged to be both good and bad, such as Heathcliff in Emily Brontë’s Wuthering Heights or Austen’s Mr Darcy. “They reveal the pressure being exercised on maintaining the total social order,” says Carroll. Boehm and Carroll believe novels have the same effect as the cautionary tales told in older societies. “Just as hunter-gatherers talk of cheating and bullying as a way of staying keyed to the goal that the bad guys must not win, novels key us to the same issues,” says Boehm. “They have a function that continues to contribute to the quality and structure of group life.” “Maybe storytelling – from TV to folk tales – actually serves some specific evolutionary function,” says Gottschall. “They’re not just by-products of evolutionary adaptation.” ●

www.newscientist.com

MARK LYTHGOE & CHLOE HUTTON/WELLCOME IMAGES

Doubts raised over brain scan findings SOME of the hottest results in the nascent field of social neuroscience, in which emotions and behavioural traits are linked to activity in a particular region of the brain, may be inflated and in some cases entirely spurious. So say psychologist Hal Pashler at the University of California, San Diego, and his colleagues, who examined more than 50 studies that relied on functional magnetic resonance imaging (fMRI) brain scans, many published in highprofile journals, and questioned the authors about their methods. Pashler’s team say that in most of the studies, which linked brain regions to feelings including social rejection, neuroticism and jealousy, researchers interpreted their data using a method that inflates the strength of the link between a brain region and the emotion or behaviour. The claim is disputed by at least two of the critiqued groups. Both argue that Pashler has misunderstood their results and that their conclusions are backed by other studies. In many of the studies, researchers scan volunteers’ brains as they complete a task designed to elicit a particular emotion. They then divide the images from the scans into cubes

Are successful traders born, not made? SUCCESSFUL financial traders may be born, not made. Men who excel at fast-paced financial trading may have been exposed to higher levels of testosterone in the uterus than their less successful colleagues. Last year, John Coates at the University of Cambridge and colleagues www.newscientist.com

called voxels, which can each contain millions of neurons, and attempt to correlate the activity of particular voxels with emotional changes reported by the volunteers. The problem arises when researchers attempt to calculate the strength of this correlation. This has to be done in two stages. The first is to identify regions in which the correlation between voxel activity and the emotion exceeds a certain threshold. In the second stage, the researchers assess the strength of the correlation in that region. Pashler recommends that two independent sets of scans be used in these two stages. If the same set

–Meaningful result, or just noise?–

is used for both, there is an increased risk of misinterpreting random noise as a genuine signal. Yet in almost 30 of the papers Pashler’s team analysed, researchers used the same scans to identify the voxels of interest and determine the final correlation. This inflates the correlation above its true value,

and has the potential to produce apparent links between emotions and brain regions when none exists, Pashler’s team claims. To demonstrate their point, the team used this technique to search for correlations in simulated brain scan data. This appeared to reveal statistically significant correlations, when in fact there were none. The critique has been peer-reviewed and accepted for publication in Perspectives on Psychological Science. Many researchers are not surprised by Pashler’s conclusions, as the more rigorous analysis that his team recommends requires more data. It is expensive to run fMRI scans and difficult to find volunteers. Nikolaus Kriegeskorte at the US National Institute of Mental Health in Bethesda, Maryland, is trying to gauge the number of neuroscience papers that use this method, because he also believes

it is problematic. And in 2007, researchers withdrew part of an fMRI paper published in Nature Neuroscience (DOI: 10.1038/ nn0107-1) after another researcher showed that random noise could have produced the reported correlation. The researchers criticised by Pashler strongly contest his team’s conclusions. Tania Singer at the University of Zurich in Switzerland says Pashler’s survey questions were “ambiguous and incomplete”, causing him to misjudge the way her group corrected for random noise. Matthew Lieberman of the University of California, Los Angeles, says that even if his 2003 study in Science (DOI: 10.1126/ science.1089134) inflates the strength of the link between feelings of rejection and physical pain, the link itself stands, as studies using different methods also identified it. Jim Giles ●

found that traders who started the day with elevated testosterone made more money than those who didn’t. He wondered whether another effect could also contribute: individuals who had higher exposure to testosterone in the uterus are more likely to feel the effects of the hormone in later life. Coates recruited 49 male “highfrequency” traders from the City of London, who buy and sell over the space of minutes or seconds, requiring high levels of confidence and quick reaction times. He measured their index to ring finger ratio - thought

by many researchers to be a marker of prenatal testosterone exposure. Traders with a longer ring finger, and therefore higher prenatal testosterone, made on average six times the profits of traders with shorter ring fingers, and tended to remain traders for longer (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0810907106). The study confirms that exposure to sex hormones early in life enables particular behaviours to develop, says Bruce McEwen of the Rockefeller University in New York, but adds that

other factors no doubt play a role in success in this particular career. Coates agrees, and cautions against bosses using finger length to make hiring decisions. The effects of high prenatal testosterone may even be a disadvantage in other types of trading. For example, other studies have suggested that people with a high index to ring finger ratio make better mathematicians. John Manning, author of The Finger Book, wonders whether finger ratios might turn out to correlate with success in other professions. Linda Geddes ●

“Some experiments correlating brain regions to feelings used a method that inflated the apparent strength of the link”

17 January 2009 | NewScientist | 11

Research news and discovery

JOEL SARTORE/NGS/GETTY

In brief– Dating droughts

Humans’ prey species evolving dangerously fast to escape us FISHING and hunting by humans may drive evolution in a way unlike anything else on Earth, and the rapid changes triggered in wild species risks severe damage to ecosytems. Chris Darimont, an evolutionary ecologist at the University of California at Santa Cruz, and his team, reviewed 34 studies that measured how fast traits such as body size and growth rate had changed in 29 species that people harvest for food. The average rate of change was three times as fast as comparable changes seen in unhunted populations,

they found (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0809235106). It was well known that hunting and fishing, which often target the largest individuals, can cause species to become smaller and mature more quickly. However, Darimont’s study is the first to show that this effect occurs for species ranging from cod to caribou (pictured), and that these species change far more quickly than they otherwise would, says Andrew Hendry, an evolutionary biologist at McGill University in Montreal, Canada. Rapid changes in size may threaten ecosystems by disrupting size-based interactions such as predation and competition, says Darimont. For example, smaller fish may no longer be big enough to eat species they once preyed on.

Try Tetris to help treat trauma PLAYING video games after a harrowing event may help to reduce the effects of the trauma. Post-traumatic stress disorder (PTSD) can trigger involuntary, distressing flashbacks in people who have been through trauma, such as soldiers or victims of rape. Emily Holmes at the University of Oxford and her team tried to spark minor flashbacks in people who did not have PTSD by 12 | NewScientist | 17 January 2009

showing them graphic videos of car crashes, drownings and surgery. Participants who played the video game Tetris for half an hour immediately afterwards had fewer flashbacks in the following week and scored lower on a standard PTSD test (PLoS One, DOI: 10.1371/journal.pone.0004153). Holmes says that playing Tetris may “use up” the brain’s visuospatial processing resources.

This could temporarily lessen its ability to lay down memories with a strong visual component, such as those that can cause involuntary flashbacks of a horrific event. Crucially, there was no difference in volunteers’ ability to recall the event in narrative terms, so playing Tetris only seemed to prevent flashbacks. Visuospatial tasks might one day be given to people after a traumatic event, but Holmes cautions that further research is needed.

CHARRED remains of ancient rainmaking fires are helping to date droughts in Iron Age Africa to within 20 years. After a several years of little or no rainfall, the Bantu people near modern-day Zimbabwe would send a rainmaker to nearby hills. “They’d burn fires with dark smoke to call black rain clouds from the mountains,” says Thomas Huffman at the University of the Witwatersrand in Johannesburg, South Africa. Villagers were also made to burn grain bins if they had planted “unlucky” foreign seeds. Huffman’s team uncovered the ashes within archaeological remains. With the help of carbon dating and analysis of tree rings they discovered and dated previously unknown droughts (Journal of Archaeological Science, DOI: 10.1016/j.jas.2008.11.026). The results also date a drought in AD 1300 thought to have made a Bantu society vulnerable to invasion from Great Zimbabwe.

Pop a pill before taking a drag? EXTRA doses of a molecule that helps to protect lung cells from the damage caused by smoking might one day reduce some of the dangers associated with the habit. Avrum Spira at Boston University School of Medicine and colleagues identified 28 microRNAs – molecules that control the expression of networks of related genes – that were less prevalent in the airways of smokers than non-smokers (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0806383106). One microRNA, called mir-218, seems to control a group of genes that help to protect lung and airway cells from smoke damage. So Spira suggests that giving smokers extra mir-218 might make their habit less hazardous. www.newscientist.com

ETHAN MILLER/REUTERS

COMMUTERS’ car exhaust doesn’t just warm the globe – it can also increase lightning strikes for miles around. During the working week, air pollution rises because of all the vehicles on the road. This effect has been shown to modify rainfall patterns both at the weekend and during the week by creating stronger updrafts of air and bigger clouds. Now it seems weekday pollution can bring lightning as well as rain. Daniel Rosenfeld of the Hebrew University of Jerusalem, and colleagues, counted strikes recorded across the US by the ground-based National Lightning Detection Network in June to August, from 1998 to 2008. In the south-eastern states, lightning strikes increased with pollution by as much as 25 per cent during the working week. The moist, muggy air in this region creates lowlying clouds with plenty of space to rise and generate the charge needed for an afternoon thunderstorm. Surprisingly, the effect was not strongest within big cities with high pollution, but in the suburbs and rural areas surrounding them. “There is a misconception that if you get away from cities, you get away from the pollution. Actually, it follows you for hundreds of miles,” says Rosenfeld, who presented the research at the American Geophysical Union meeting in December. He says the heat generated by urban areas may locally override pollution’s effect on lightning.

www.newscientist.com

Mouse immune system devours brain tumours COULD a cancer patient’s immune cells be coaxed into gobbling up the deadliest brain tumours? Most people with glioblastoma multiforme die within a year of diagnosis, as standard treatments cannot eradicate these tumours. One potential approach is to harness the immune system to fight the tumours. The trouble is that the brain contains few immune cells, and those that are present often fail to recognise tumours as targets for attack. These are evolutionary adaptations to protect healthy

brains from potentially damaging immune responses. Now Maria Castro, Pedro Lowenstein and their colleagues at Cedars Sinai Medical Center in Los Angeles, California, may have a solution: they have persuaded the immune systems of mice to shrink, and even completely destroy, some glioblastomas. They injected the mice’s tumours with a gene that attracts chemotherapy drugs, and one that attracts immune cells. When they gave the mice chemotherapy, the drugs killed only a fraction of

the tumour but crucially, the dying cells released a protein that stimulates brain immune cells to recognise tumour cells as a target and attack. And because immune cell levels are boosted due to the second inserted gene, the immune response to tumours was strong enough in some cases to entirely destroy them (PLoS Medicine, DOI: 10.1371/journal. pmed.1000010). The researchers hope to begin clinical trials in humans soon and test the method on cancers elsewhere in the body.

Mercury and Mars – separated at birth

corresponding to Venus and Earth. A number of smaller bodies also form within the ring. These are typically scattered away by the larger two, but if they experience collisions on the way, they can end up in stable orbits similar to those of Mercury and Mars. Once beyond the ring, they cannot acquire mass and so remain pint-sized. “This is nicely consistent with various properties of Mercury and Mars,” says Hansen, who presented the work at the American Astronomical Society meeting in Long Beach, California. Both small planets have features that could have been caused by giant impacts. In one run of Hansen’s simulation, Earth received a smash, too, much like the one thought to have created the Moon.

NASA

Cars, the spark plugs for the sky

Black holes blew up from nothing HOW did black holes lurking at the centre of galaxies like ours get so big so quickly? That’s the puzzle posed by the discovery of fully grown, supermassive black holes surrounded by fledgling galaxies early in the history of the universe. Chris Carilli of the National Radio Astronomy Observatory in Socorro, New Mexico, and colleagues studied four galaxies from less than 2 billion years after the big bang. They found the black holes at the centres of these galaxies were as heavy as anything seen in the modern universe, with one estimated to have the mass of 20 billion suns. Meanwhile, it looked as if the host galaxies had only begun to grow, with only modest masses compared with galaxies harbouring similarly sized black holes today. “This suggests the black holes came first,” says Carilli, who presented the results at a meeting of the American Astronomical Society in Long Beach, California. Whether the seed black holes formed from the contraction of massive gas clouds or the collapse of stars, the black holes must have grown at tremendous rates to get so big so early on.

LINE up Mercury, Venus, Earth and Mars according to their distance from the sun and you’ll see their size distribution is close to symmetrical, with the two largest planets between the two smallest. That would be no coincidence – if the pattern emerged from a debris ring around the sun. Brad Hansen of the University of California, Los Angeles, built a numerical simulation to explore how a ring of rocky material in the early solar system could have evolved into the planets. He found that two larger planets typically form near the inner and outer edges of the ring,

17 January 2009 | NewScientist | 13

Comment and analysis–

Under one sky THE Acropolis in Athens, the elaborate temples of Angkor in Cambodia, and the stone statues of tiny Easter Island, home for 1000 years to the most isolated human community on Earth. These are among the 878 World Heritage Sites (both cultural and natural) protected by UNESCO as places of “outstanding universal value” to humankind. As such, each contains extraordinary creative masterpieces from lost cultural traditions. And each represents a vestige of the past that stands out as a powerful source of inspiration to people across the planet. Yet one aspect of our cultural heritage – astronomy – is woefully under-represented on the World Heritage List. To those of us in the modern, lit-up world, the first time that we see a truly dark night sky can be breathtaking. But until relatively recently, most people experienced this spectacle every clear night, wherever they lived. If we want to appreciate the beliefs and practices reflected in the architecture of ancient temples and tombs, we cannot ignore their relationship to the sky. The World Heritage List does contain a few ancient sites and monuments with links to the sky, but these were selected because of their broader archaeological and cultural significance. They include the Neolithic passage tomb of Newgrange in Ireland, aligned so the sun shines in only for a few minutes after sunrise on the shortest days of the year. This shows that people 5000 years ago saw a link between ancestors and the sun. There’s also Stonehenge in Wiltshire, UK, with its well-known connection to midsummer sunrise and midwinter sunset; Chaco Canyon in New Mexico, featuring the Fajada Butte “sun dagger” that splits a spiral carving at noon on the summer solstice; and several pre-Columbian sites in Mexico, including Chichen Itza, Monte Alban and Palenque. The Mesoamerican preoccupation with solar, lunar and planetary cycles and conjunctions is 14 | NewScientist | 17 January 2009

ANDRZEJ KRAUSE

All peoples, past and present, share a fascination with the sky. We must save our astronomical heritage before it is lost, says archaeoastronomer Clive Ruggles

manifested in inscriptions, alignments, and the existence of “zenith tubes” down which the light of the sun shone at noon on the two days in the year when it passed vertically overhead. Despite these examples, there have never been any clear guidelines for nominating World Heritage Sites based on their relationship to astronomy, and this leaves many key sites vulnerable to neglect and irreversible damage. To try and fix this, UNESCO is now encouraging member states to put forward astronomical nominations, and the International Astronomical Union (IAU) will be working with UNESCO throughout 2009 to come up with clear criteria for judging the merits of these sites. It is a fitting task for the International Year of Astronomy, which celebrates the 400th anniversary of Galileo’s first use of a telescope to gain an unprecedented view of the sky. As well as prehistoric sites, this Astronomy and World Heritage Initiative will include sites related to the history of modern astronomy, such as observatories, instruments and

“Every human culture has a sky, and strives to interpret what people perceive there”

places where key discoveries were made. This is an important part of science heritage in general (also poorly represented on the World Heritage List). Again, a few examples are recognised, but mostly as part of sites that have broader significance. These include the 15th-century observatory of Ulugh Beg in Samarkand, Uzbekistan, the 18th-century observatory of St Petersburg in Russia, and the Old Royal Observatory in Greenwich, UK. When protecting sites, UNESCO recognises that they did not exist in isolation, though it may seem that way when we visit them in the modern landscape. They stood among all the places where people lived, worked and died. Hence the Stonehenge and Avebury World Heritage Site includes not just the two monuments, but the entire “cultural landscapes” in which they were situated, replete with evidence of Neolithic settlements, farming practices and places of burial. In the same way, astronomical heritage sites we should also protect and preserve the crucial remaining part of the visible environment – the dark night sky. This links the Astronomy and World Heritage Initiative with other efforts to protect the night sky from light pollution, such as through the establishment of Starlight Reserves. At Stonehenge, for example, we can hope that the proposed re-routing of nearby roads might not only restore this monument to its landscape, but also to a darker, more starry, night. Every human culture has a sky, and strives to interpret what people perceive there. The understanding they develop forms a vital part of their knowledge concerning the cosmos and their place within it. So astronomy is not just a modern science but a reflection of how all peoples past and present, see themselves in relation to the universe. With the globalisation of human culture proceeding at relentless pace, safeguarding our astronomical heritage is a vital part of the race to save the more fragile aspects of our common cultural heritage before they are lost forever. ● Clive Ruggles is emeritus professor of archaeoastronomy at the University of Leicester, UK, and chair of the IAU’s working group on astronomy and world heritage www.newscientist.com

Letters– Models need data From Ralph Rayner, Institute of Marine Engineering, Science and Technology Lenny Smith makes a number of important points concerning the consequences of overselling the results from climate models, but he omits an important one (6 December 2008, p 42). Those who overstate the present capability of climate models risk creating the perception that models can substitute for measurement and so undermine the case for adequate observation and monitoring. It is only through these measurements and observations that we can reduce the models’ uncertainties, by improving our understanding of the processes driving both natural and anthropogenic climate change. Excessive reliance on models can also result in reduced support for critical long-term observations against which the models’ climate projections are validated and their accuracy determined. As Smith says, climate models provide useful information about plausible risks. Only carefully planned systematic observation and monitoring will permit us to properly understand what is happening to our climate and the elucidation of the processes at work in determining any future long-term change. London, UK

Going off-grid From Tim Douglas One important item was missing from your power-saving suggestions (6 December 2008, p 30) in the article “Life unplugged”. Home heating takes a lot of power, especially when it comes to getting fresh air into the house. Could we not virtually eliminate energy use for heating (or cooling) incoming air by using a counter-flow heat exchanger? Cold incoming air would be 16 | NewScientist | 17 January 2009

heated by warm air going out through the heat exchanger, and vice versa when it is hot outside. Counter-flow heat exchangers are so effective that they are used industrially. Why they are not used domestically baffles me. Collinsvale, Tasmania, Australia From David Clarke Chris Knapton may be right to put some of the blame on the utilities and government for the slow growth of small-scale generation (20/27 December 2008, p 18), but we should not underestimate the potential problems with this technology. As the amount of small-scale generation grows, with each little generator doing its own thing, it will become difficult to maintain system stability – something that the big utilities and the operators controlling the electricity grid at present do pretty well. Maintaining local voltage stability may be a particular problem. We need technology to automatically control the output of small-scale generation in response to system conditions. With luck the “smart grid” initiatives will deal with this problem, but I do not think we’re there yet. Royston, Hertfordshire, UK From Steve Plater Gaia Vince should have used the estimator of solar energy yields published by the Renewable Energy Unit at the European Union’s Joint Research Centre (http://sunbird.jrc.it/pvgis): it would have told her that in the UK 8 square metres of panel are required to gain 1 kilowatt peak output and 800 or so kilowatthours per year (“For the record”, 3 January, p 17). Vince also tells us that in Germany “homeowners selling back renewably generated power are guaranteed to get four times the market rate charged to consumers for electricity”. The German feed-in tariff is indeed admirable, but it is not that generous. The market rate to consumers is at present 20 to 21

cents per kilowatt-hour. The feedin tariff for electricity generated by a small rooftop photovoltaic array this year is just over 46 cents, and for arrays installed next year it will be 43 cents. The starting rate will drop by 8 to 10 per cent each year. Rates for electricity from other renewables are lower. Sevenoaks, Kent, UK

From Vivienne Mugford I have just had eight solar panels installed on my roof, occupying 10.2 square metres. I now realise, too late, that the average output is dramatically less than the peak output. My system, with a grant, cost me £7200 – and will take 37 years to break even, under the current arrangements with electricity suppliers. Though the return on my money is better than I would now get from a savings account, I feel misled by the supplier, who gave me only peak values at point of sale. Ottershaw, Surrey, UK From Rolfe Bridson Reading of the generous price premium offered in Germany for selling surplus electricity generated to the power companies (6 December 2008, p 30), I was struck by the possibility of people fraudulently buying in power from the grid at the lower cost and then selling it back at the higher rate. Has anyone thought about how to plug this loophole? Alton, Hampshire, UK

Why menopause? From Stephen Cadney Alison Motluk makes no mention of the opportunity an early menopause offers to pass on culture, and the great advantage this provides (13 December 2008, p 41). It is obvious that we are separated from other primates by culture – and by being hugely more successful in evolutionary terms than they. Pregnancy is a life-threatening condition which, in societies that have no access to modern medicine, sees off many a grandmother before she has the leisure time to educate her grandchildren. Rachel Caspari, now at Central Michigan University, and Sang-Hee Lee of the University of California, Riverside, make a convincing case that with grandparents came civilisation (10 July 2004, p 14). Assuming that male grandparents tended towards the autistic end of the personality spectrum and preferred power struggles and sitting around to being educators of the younger generations, a genetic variation that allowed an early menopause looks as if it conferred a huge evolutionary advantage. Manchester, UK From Marco Overdale You report Michael Cant saying that the lack of overlap in the fertility of mothers and daughters is striking, and that this can explain why human women experience the physical switch of menopause, rather than a slow decline in fertility. What is equally striking is the commonality in the age of menopause across several species of primates with different average lifespans. One factor that would, in evolutionary terms, result in the physical cessation of fertility at a particular age is a decline in the viability of offspring conceived after that age. In a longer-lived species this could initially tend to terminate fertility at a set age independent of lifespan. www.newscientist.com

See newscientist.com for letters on: ● Going off-grid ● Stirling service

As a mother’s age increases, the likelihood her offspring will survive or be healthy decreases. She is also likely to be less able to care for more young children. The reproductive viability of later offspring is thus likely to decrease. If this fall-off with mother’s age at conception is sufficiently steep, those who continue to conceive successfully as age increases will be selected against because their later offspring will not reproduce. Other factors would also need to operate to push reproduction into a younger age group, so that a greater proportion of a women’s offspring will end up reproducing. Those identified by Cant would be such a possible driving force. Wellington, New Zealand From Carole Karan As a woman of happily postmenopausal age, I can think of several additional things that encourage menopause. Anything a new birth does that increases the likelihood of one or more previous children dying would encourage a cut-off of late fertility. For example, the higher rate of defects in births from older women would mean wasting resources on some pregnancies that will never lead to another adult at the expense of older offspring. Older women are also much more likely to be widowed, and the food that mates supply should not be underestimated. Mebane, North Carolina, US

little faster than a 1980s model running pre-Windows software. The assumption that Moore’s law will compensate for inefficiently designed systems leads to Prior’s conjecture: sloppy software losses will negate Moore’s law gains. Malvern, Worcestershire, UK

in the west was the narrow interpretation of religious texts. Only when Greek texts rescued and translated by the Arabs from the moribund Byzantine empire found their way to the west, and the shackles on learning were eased, did advances become possible again. Lincoln, UK

Greeks’ gifts

From Stuart Leslie Jo Marchant asks why the Greeks did not use their science to create useful technology (13 December 2008, p 36). Could it be because Greek civilisation was based on slavery? Plato and Aristotle both wrote that civilisation was impossible without slaves. This implies the answer to her second question: to what better use could technology be put than understanding and demonstrating the nature of the universe? I suggest that improving the lot and lessening the suffering of human beings takes first place every time. Dorrigo, New South Wales, Australia

From Nicholas Dore You speculate on what the Greeks might have achieved had the Romans not supplanted their culture (13 December 2008, p 5). This rather misunderstands the role of the Romans, who were great admirers of the Greeks and eagerly adopted much of Greek thought and culture. The Romans might not have been particularly original thinkers or inventors, but adapted and used whatever they found in the societies they conquered. The failure of the Greeks to take their technology further was more likely due to the chaotic rivalry between their city-states. This effectively crippled them, both in their resistance to Rome and in adapting technology to everyday life. Even so, much knowledge might still have survived to allow further advances had the rise of

Less is Moore From Andy Prior Scientists and engineers have indeed done an impressive job in realising Moore’s law over the years (6 December 2008, p 35). What a pity that the average PC user has not seen the equivalent leap in “user experience”. A combination of operating system bloat, poorly configured and maintained networks, and overzealous virus checkers means that for many, PCs today seem www.newscientist.com

Christianity not got in the way. From the outset, Christianity regarded learning, in particular inquiry into the nature of the physical world, as positively dangerous. All that passed for learning for over 1000 years

Dangerous sex in a pill From Tessa Kendall Bernd Brunner is “terrified” by Clare Wilson saying an “intelligent and well-informed” gay man “sometimes” has unsafe sex. He sees this as a contradiction, and believes this kind of behaviour to be unusual (20/27 December 2008, p 18). If his reasoning were correct, then intelligent, informed people would never smoke, take drugs, drink to excess or be overweight. Smart people do dumb things, especially for sex. Human nature often contradicts common sense. London, UK

Canine calculus From Mike Legge Marcus du Sautoy opines that we have the innate mathematics skills needed to survive things being thrown at us and gauge

enemies’ sizes (29 November 2008, p 44). My dog can compute the trajectory and velocity of an object far better than I can. Does this mean that she is better at mathematics than I am? In contrast, small yappy dogs seem not to realise how small they are. Are they therefore both vertically and mathematically challenged? Nanaimo, British Columbia, Canada

Gunner Copernicus From Andrew Brooker Copernicus may have expelled us in principle from the centre of the universe (15 November 2008, p 32), but I am reminded of an incident in Spike Milligan’s memoirs of the British army: Officer (shouting): “You there, what are you doing over there?” Milligan: “Uh, everybody gotta be somewhere, sir.” Bristol, UK

For the record ● Scud missiles are not intercontinental ballistic missiles: they have a range of only 1000 kilometres and are classed as intermediate-range ballistic missiles (13 December 2008, p 26). Letters should be sent to: Letters to the Editor, New Scientist, 84 Theobald’s Road, London WC1X 8NS Fax: +44 (0) 20 7611 1280 Email: [email protected] Include your full postal address and telephone number, and a reference (issue, page number, title) to articles. We reserve the right to edit letters. Reed Business Information reserves the right to use any submissions sent to the letters column of New Scientist magazine, in any other format.

17 January 2009 | NewScientist | 17

KELLY HARRIGER/CORBIS

Technology HOT-AIR BALLOONS POWER UP

AN IMAGING device is being used to assess the plant diversity within a rainforest without setting foot there. Greg Asner, an ecologist at the Carnegie Institution in Washington DC, is developing it as a way of measuring deforestation, and the damage done by logging. Asner uses a laser scanner linked to a spectrometer on board an aircraft to fire visible light towards the ground and analyse the wavelengths that are reflected from the leaves. This generates a three-dimensional map of the chemical composition of the trees, from the canopy to the forest floor, and hence the biodiversity of the forest. The system is being upgraded to detect infrared wavelengths, too. Asner says this will allow it to spot more chemicals and so detect more subtle differences among tree species.

10

–An alternative energy source–

Meet your virtual mum and dad IT IS a poor substitute for the real thing, but the US government is hoping a “virtual parent” could provide emotional support for the children of servicemen and women while they are away on active duty. The Department of Defense is soliciting proposals for a computer program that would enable young children to interact

million iTunes tracks are to be made copiable. Apple is dropping copy protection in response to pressure from consumers

Most American teenagers say they have encountered racial abuse while online 80 70 60 50 40 30 20 10 0

African-American White Other/mixed race

Witnessed racism directed at others

with a virtual version of their parent. Officials hope it could provide reassurance and general chat when phone or internet contact is not possible. The DoD believes that “the stresses of deployment might be softened if spouses and especially children could conduct simple conversations with their loved ones in immediate times of stress or prolonged absence”. More than 155,000 kids have at least one parent deployed in Iraq or Afghanistan on military duty.

GIZMO

RACISM ON THE NET

Subjected to racist comments

SOURCE: JOURNAL OF ADOLESCENT HEALTH

Flying eye maps rainforest’s health

and a frequency of one revolution per hour,” says Edmonds. For roughly the same cost as wind power, Edmonds has calculated that a large 44-metre-diameter recreational balloon could generate 50 kilowatts, enough to supply energy to about 10 homes. Doubling the diameter of the balloon would increase power production tenfold, substantially reducing costs, he says. Using air heated by the sun to generate power has been attempted before: solar towers use the rising air to turn turbines. But a prototype solar tower in Manzanares in Spain proved too short even at 200 metres, limiting the amount of energy that could be captured from the rising air. Building towers of 500 metres or more has so far proved too expensive.

Per cent

For those who dislike the sight of wind turbines on the horizon, would a spectacular hot-air balloon farm be more acceptable? Ian Edmonds, an environmental consultant with Solartran in Brisbane, Australia, has designed a giant engine with a balloon as its “piston”. A greenhouse traps solar energy, providing hot air to fill the balloon. As the balloon rises, it pulls a tether, which turns a generator on the ground. Once the balloon has reached 3 kilometres, air is released through its vent and it loses buoyancy. This means less energy is needed to pull the balloon back down again, resulting in a net power gain (Renewable Energy, DOI: 10.1016/ j.renene.2008.06.022). “It is like a huge two-stroke engine, with a capacity of 45 million litres, a stroke of 3 kilometres,

Future gadgets will not only be transparent – they will also be bendy. Researchers at Sungkyunkwan University in Suwon, South Korea, have deposited carbon atoms on a nickel base, then etched away the nickel to leave transparent sheets of graphene. The material’s high conductivity is not affected by bending and stretching, making it ideal for electrodes in wearable computers (Nature, DOI: 10.1038/nature07719). Time was when the Palm Pilot was the trendy hand-held gadget of choice, but it has long since been overtaken in the fashion stakes by the BlackBerry and Apple iPhone. Now Palm hopes to strike back with its forthcoming “Pre” phone, which it promises will feature similar touch-screen technology to the iPhone, plus a pull-out keyboard. It will also offer instant messaging, and will be charged up wirelessly.

“I didn’t go near it. I was worried it might explode and kill me” Kamal Prasad Sharma, a 12-year-old student at Saraswati Secondary School near Kathmandu in Nepal, on his first sight of a computer. The school is taking part in the E-library project, initiated by the Help Nepal Network to improve literacy and computer awareness (BBC online, 5 January)

www.newscientist.com

17 January 2009 | NewScientist | 19

Technology

Eyes wide open, please, let’s look into your brain A laser version of ultrasound identifies brain tumours and neurodegenerative diseases from your eyes only DUNCAN GRAHAM-ROWE

THE eyes may be the windows to the soul, but they also make pretty good peepholes into the brain. Thanks to an optical version of ultrasound, it is becoming possible to locate and monitor the growth of brain tumours, and to track neurodegenerative conditions like multiple sclerosis, Alzheimer’s and Parkinson’s disease – all by peering into the eye. The brain is connected to each eye by an optic nerve, so any degeneration of the brain caused by such diseases can also damage cells along the nerve and in the retina, says Helen Danesh-Meyer, an eye surgeon and neuroophthalmologist at the University of Auckland Medical School in New Zealand. Indeed, a loss of visual function is one of the first symptoms in many people with a neurodegenerative condition. Although evidence of a link between degeneration of the optic nerve and diseases such as Alzheimer’s has been around since the late 1980s, without instruments capable of measuring the retinal changes accurately it is only recently that this knowledge could be put to use, says Danesh-Meyer. The accuracy of ophthalmological tools has greatly improved in the last few years. Developments include 20 | NewScientist | 17 January 2009

a type of laser-camera technique called Heidelberg retina tomography (HRT), and a laser device called GDx, both of which can be used to scan the shape and thickness of optical nerve fibres at the back of the eye. Both tools are now widely used to manage glaucoma, but in 2006 Danesh-Meyer became one of the first researchers to use them to study neurodegenerative diseases by looking at the region of the retina where ganglion cells meet to form the optic nerve – a region known as the optic nerve disc (OND). In a trial involving 40 Alzheimer’s patients and 50 healthy volunteers, she was able to show that people with Alzheimer’s had a distinctive enlargement to a cup-shaped part of their OND and

it became commercially available in 2006 and is fast becoming a standard tool for the management of glaucoma and diabetic retinopathy. When applied to the OND, it produces highly detailed two and three-dimensional images of the subsurface retinal tissue, says Denise Valenti at

“People with Alzheimer’s have a distinctive shape to the disc of their optic nerve” a progressive thinning of the retinal nerve fibres within the disc. Following this discovery, researchers have been using even more accurate instruments to track degenerative changes in the OND to monitor the progression of diseases like Alzheimer’s, Parkinson’s and MS. But it has been the emergence of optical coherence tomography (OCT) that appears most promising:

Boston University, who has been using OCT to study Parkinson’s and Alzheimer’s. The technique works very much like ultrasound, but bounces light off the tissue instead of sound waves. One beam of light is fired at the tissue and another at a reference mirror. When the reflected beams have travelled an identical distance, interference will make their

combined beam brighter than if the distances are different. So by reflecting one beam off of different layers of tissue, and moving the reference mirror until the combined reflected beam is brightest, the technique can measure the depths of each section of tissue and build up a detailed image of its structure. It has proved particularly useful in ophthalmology because the semi-transparent nature of retinal tissue makes it possible for OCT to penetrate to greater depths – up to several millimetres. When applied to the OND it can give information about both the shape and thickness of retinal nerve fibres, allowing even subtle changes to be tracked. Such changes can be used to monitor the progression of diseases non-invasively and relatively cheaply. Unlike MRI, which is expensive and can require www.newscientist.com

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Virtual double flexes your muscles

A SYSTEM that creates a virtual body double of a person’s skeleton and muscles could help fitness fanatics or people trying to regain movement after an illness by showing them how well they are exercising. The Human Body Model, developed by Motek Medical in Amsterdam, the Netherlands, uses a virtual double to show which muscles a person is using by highlighting them in green (see image). The force being generated is shown by the intensity of the colour. “It allows you to see the muscle groups you are using in real time, and even the forces they are creating, which are usually invisible,” says Motek’s founder Oshri Even-Zohar. The user’s on-screen output is not a direct measure of their muscle activity, but is based on existing models of the anatomy and physics of the human body and is intended as a tool to help the patient.

Users carry out exercises, such as running on a treadmill, while wearing a suit with 47 reflective markers placed in the positions of specific muscles. While the person runs, infrared strobe lights, flashing several hundred times a second, help eight cameras to track the markers. Sensors on the floor of the treadmill can also be used to measure the force applied to the ground by the user’s feet to give more information on their muscle output and the load on their joints. The final stage is to feed this information into computer models, which help create the detailed onscreen display of the user. The software used to help create the double was trained by directly measuring the force generated by people’s muscles while recording their motion and the electrical activity of their muscles. This could only be done for some movements and forces, though, such as pushing against weights. “There is no tool in medical science that allows you to measure all the muscle forces in motion,” says Even-Zohar. The system is being tested at Sheba Hospital in Tel Aviv, Israel, where it is helping people regain movement after a stroke. Researchers at the Cleveland Clinic in Ohio are also using the system to study gait and locomotion in healthy, active people. Tom Simonite ● MOTEK MEDICAL

JONATHAN NOUROK/STONE

with MS whose eye function is normal, there are marked differences in OND shape and fibre thickness compared with healthy people. “MS researchers are very excited about OCT,” she says. The technology is also proving its value as a tool for monitoring brain tumours, which can affect vision by pressing on the optic nerve. Such pressure will cause damage to different parts of the OND, depending on where in the brain the tumour is located, says Danesh-Meyer. What’s more, the extent of the thinning of the nerve-disc fibre can also reveal whether vision will be restored upon removal of the tumour. In the case of one patient who was 24 weeks pregnant following several IVF attempts, OCT monitoring allowed surgeons to hold off on removing her brain tumour until well into the third trimester, when the fetus had a better chance of survival. The usual treatment would have been to operate immediately to prevent permanent vision loss, but this would have risked inducing premature labour. By monitoring the compression on the optic nerve –Look into my eyes, doctor– to ensure it did not reach the point at which permanent damage was inevitable, Danesh-Meyer was patients to remain still for an hour or more, OCT is increasingly able to keep tabs on the tumour’s growth and delay the surgery. As available in clinics and can be a result, the baby was born safely carried out in a few minutes. “It’s extremely inexpensive compared and the patient kept her vision. The ultimate aim for many to other tests,” says Valenti. using OCT is to diagnose diseases One possibility is to use OCT before symptoms arise. The to monitor the effectiveness of treatments for neurodegenerative difficulty with this is that the thickness of retinal nerve fibres diseases, says Danesh-Meyer: “These drugs can have a lot of side can vary from person to person, says Danesh-Meyer, so there is effects, so if they are not having a not always a clear baseline from benefit then you won’t want to which to compare patient scans. continue with them.” Eventually though, the low cost Laura Balcer, a neurologist at and simplicity of the technology the University of Pennsylvania School of Medicine in Philadelphia, may make it feasible for people to be given an OCT scan of each eye has been using OCT on patients taking part in MS drug trials to try at a young age, to give doctors a record of their healthy retinal to establish if the system can nerve, says Danesh-Meyer. accurately gauge drug efficacy. Such an objective tool would allow With regular screening, some neurological conditions could be symptoms to be picked up that spotted incredibly early. “We’re might otherwise go unreported, really just at the cusp of knowing she says. For example, OCT has already shown that even in people where this is all going.” ●

–The future of exercise?– 17 Janaury 2009 | NewScientist | 21

Technology

CLUMPS of wet hair could be the latest thing in nanotechnology, creating microscopic spiral structures that may form drug delivery systems and surfaces whose colour can be tuned. While nature makes use of spiral structures of all sizes, engineers have found it hard to create small spirals. “We can make helical structures on the molecular scale and on macroscales, but at the level of nanometres and micrometres it has never been achieved,” says Joanna Aizenberg of Harvard University.

Mini boat travels by bending water

Now Aizenberg and her team have found a way to make nanospirals self-assemble. They start with an array of epoxy-resin bristles, each 300 nanometres thick and 4 to 9 micrometres long. These are immersed in a mixture of ethanol and water and then taken out and left to dry. As the liquid evaporates, its surface tension draws the bristles together in an effect related to capillary action. At first, the tension pulls groups of four bristles together to form what look like miniature Eiffel Towers. Then, as the liquid evaporates further, the four bristles slide past one another and intertwine, making the towers twist. Finally, groups of twisted bristles are pulled together into larger swirls (see a gallery of nanospiral images at www.newscientist.com/ article/dn16372). For this to work, a range of parameters must be optimised. Bristle stiffness and the surface tension of the liquid have to be

chosen carefully, and adhesion between the bristles has to be just right. “If it is too weak they will spring back when they dry out, if it is too strong they will never slide and turn around each other,” says Aizenberg. This makes the choice of materials crucial. In early experiments, the structures spiralled clockwise or anticlockwise at random. To control the direction of twist,

“One idea is for surfaces that change colour as the spirals curl and uncurl” the assembly can be tilted or the bristles given an elliptical cross section, says Aizenberg (Science, DOI: 10.1126/science.1165607). A uniform direction of twist would be vital for some of the applications Aizenberg has in mind. As the size of these spirals is comparable to the wavelength of visible light, an array of them would affect light in interesting

MENISCUS PROPULSION Applying a voltage causes the Teflon at the back of the boat to attract water instead of repelling it, generating an overall force that pushes the boat forward SWITCH

HYDROPHOBIC TEFLON v FORCE

ELECTRODE

Water’s meniscus curves downwards

BATTERY

Nanospirals – a new twist on smart materials

FORCE

WATER

22 | NewScientist | 17 January 2009

v BATTERY

WATCHING Sung Kwon Cho’s model boat glide silently across the still water with no propellers or sails, you’d be forgiven for thinking a phantom hand was drawing the vessel forward. The boat is actually being driven by water surface tension, the same force that allows some insects to skate across the surface of a pond. The design is inspired by Pyrrhalta beetle larvae, which also use surface tension to propel themselves. Since it requires no moving parts, the method should be more robust than those involving propellers and may use just a

Water’s meniscus curves upwards

FORCE

DIRECTION OF MOVEMENT

FORCE

hundredth of the power. This could be ideal for extending the working life of cheap, environmentsensing robots that roam the world’s oceans, says Cho, who is at the University of Pittsburgh in Pennsylvania. Normally, the surface tension of the water surrounding a floating object is equal on every side. To upset this balance and create

a forward thrust, Cho’s team attached an electrode to the back of the boat that alters the curve of the water’s meniscus. The electrode is coated in an insulating polymer and Teflon, which is normally hydrophobic. Applying a potential to the electrode changes the insulating layer’s charge distribution and makes the

ways. This has already been seen, says Aizenberg: “The colour of our substrate actually changes during assembly.” The hope is to develop tunable optical devices that change colour as the spirals curl and uncurl, but Aizenberg is reluctant to say more. “I don’t want to go into details before our studies are complete.” Further experiments have shown that as the bristles twist, they can grasp tiny spheres. This could lead to a new kind of adhesive which, in principle, could be switched off by rewetting the bristles to make them untwist. This grasping property could also be used to target drug delivery to a specific location inside the body, says Aizenberg. A set of bristles twisted around a particular drug might be made to untwist and release their cargo in the right spot by the presence of a particular chemical. Stephen Battersby ●

electrode more attractive to water – a process called electrowetting. This extra attraction changes the shape of the water’s meniscus so that it curves upwards rather than downwards at the back of the boat, changing the balance of forces and pushing the boat forward (see diagram). In tests to be presented later this month at the MEMS 2009 conference in Sorrento, Italy, the team propelled a 2-centimetre-long prototype at roughly 4 millimetres per second. “By streamlining the boat and optimising the electrodes, we could achieve speeds of 10 centimetres per second,” says Cho (a video of the boat in action is at www.snipurl.com/9ut8w). Ramin Golestanian from the University of Sheffield in the UK is impressed with the work. “It’s a very clever trick that puts fundamental physics into practice,” he says. He thinks it should be simple to manufacture robots with a series of these electrodes along their side to provide very precise motion control. David Robson ● www.newscientist.com

●

DRIVING through the countryside south of Hanover, it would be easy to miss the GEO600 experiment. From the outside, it doesn’t look much: in the corner of a field stands an assortment of boxy temporary buildings, from which two long trenches emerge, at a right angle to each other, covered with corrugated iron. Underneath the metal sheets, however, lies a detector that stretches for 600 metres. For the past seven years, this German setup has been looking for gravitational waves – ripples in space-time thrown off by superdense astronomical objects such as neutron stars and black holes. GEO600 has not detected any gravitational waves so far, but it might inadvertently have made the most important discovery in physics for half a century. For many months, the GEO600 teammembers had been scratching their heads over inexplicable noise that is plaguing their giant detector. Then, out of the blue,

extension of our best understanding of black holes, and something with a pretty firm theoretical footing. It has also been surprisingly helpful for physicists wrestling with theories of how the universe works at its most fundamental level. The holograms you find on credit cards and banknotes are etched on two-dimensional plastic films. When light bounces off them, it recreates the appearance of a 3D image. In the 1990s physicists Leonard Susskind and Nobel prizewinner Gerard ’t Hooft suggested that the same principle might apply to the universe as a whole. Our everyday experience might itself be a holographic projection of physical processes that take place on a distant, 2D surface. The “holographic principle” challenges our sensibilities. It seems hard to believe that you woke up, brushed your teeth and are reading this article because of something happening on the boundary of the universe. No one knows what it would mean for us if we really

All the world’s a hologram a researcher approached them with an explanation. In fact, he had even predicted the noise before he knew they were detecting it. According to Craig Hogan, a physicist at the Fermilab particle physics lab in Batavia, Illinois, GEO600 has stumbled upon the fundamental limit of space-time – the point where space-time stops behaving like the smooth continuum Einstein described and instead dissolves into “grains”, just as a newspaper photograph dissolves into dots as you zoom in. “It looks like GEO600 is being buffeted by the microscopic quantum convulsions of space-time,” says Hogan. If this doesn’t blow your socks off, then Hogan, who has just been appointed director of Fermilab’s Center for Particle Astrophysics, has an even bigger shock in store: “If the GEO600 result is what I suspect it is, then we are all living in a giant cosmic hologram.” The idea that we live in a hologram probably sounds absurd, but it is a natural 24 | NewScientist | 17 January 2009

do live in a hologram, yet theorists have good reasons to believe that many aspects of the holographic principle are true. Susskind and ’t Hooft’s remarkable idea was motivated by ground-breaking work on black holes by Jacob Bekenstein of the Hebrew University of Jerusalem in Israel and Stephen Hawking at the University of Cambridge. In the mid-1970s, Hawking showed that black holes are in fact not entirely “black” but instead slowly emit radiation, which causes them to evaporate and eventually disappear. This poses a puzzle, because Hawking radiation does not convey any information about the interior of a black hole. When the black hole has gone, all the information about the star that collapsed to form the black hole has vanished, which contradicts the widely affirmed principle that information cannot be destroyed. This is known as the black hole information paradox. Bekenstein’s work provided an

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Could our three dimensions be the ultimate cosmic illusion? A German detector is picking up a hint that we are all mere projections, says Marcus Chown

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Cover story |

Can you see a 3D world in this 2D image? If not, turn to page 27

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17 January 2009 | NewScientist | 25

Has GEO600’s laser probed the fundamental fuzziness of space-time?

contained inside the volume of the universe. Since the volume of the spherical universe is much bigger than its outer surface, how could this be true? Hogan realised that in order to have the same number of bits inside the universe as on the boundary, the world inside must be made up of grains bigger than the Planck length. “Or, to put it another way, a holographic universe is blurry,” says Hogan. This is good news for anyone trying to probe the smallest unit of space-time. “Contrary to all expectations, it brings its microscopic quantum structure within reach of current experiments,” says Hogan. So while

“Incredibly, the experiment was picking up

unexpected noise – as if quantum convulsions were causing an extra sideways jitter” hundred billion billion times smaller than a proton. This distance is known as the Planck length, a mere 10-35 metres. The Planck length is far beyond the reach of any conceivable experiment, so nobody dared dream that the graininess of space-time might be discernable. That is, not until Hogan realised that the holographic principle changes everything. If space-time is a grainy hologram, then you can think of the universe as a sphere whose outer surface is papered in Planck length-sized squares, each containing one bit of information. The holographic principle says that the amount of information papering the outside must match the number of bits 26 | NewScientist | 17 January 2009

the Planck length is too small for experiments to detect, the holographic “projection” of that graininess could be much, much larger, at around 10-16 metres. “If you lived inside a hologram, you could tell by measuring the blurring,” he says. When Hogan first realised this, he wondered if any experiment might be able to detect the holographic blurriness of space-time. That’s where GEO600 comes in. Gravitational wave detectors like GEO600 are essentially fantastically sensitive rulers. The idea is that if a gravitational wave passes through GEO600, it will alternately stretch space in one direction and squeeze it in

WOLFGANG FILSER/MAX PLANCK SOCIETY

important clue in resolving the paradox. He discovered that a black hole’s entropy – which is synonymous with its information content – is proportional to the surface area of its event horizon. This is the theoretical surface that cloaks the black hole and marks the point of no return for infalling matter or light. Theorists have since shown that microscopic quantum ripples at the event horizon can encode the information inside the black hole, so there is no mysterious information loss as the black hole evaporates. Crucially, this provides a deep physical insight: the 3D information about a precursor star can be completely encoded in the 2D horizon of the subsequent black hole – not unlike the 3D image of an object being encoded in a 2D hologram. Susskind and ’t Hooft extended the insight to the universe as a whole on the basis that the cosmos has a horizon too – the boundary from beyond which light has not had time to reach us in the 13.7-billion-year lifespan of the universe. What’s more, work by several string theorists, most notably Juan Maldacena at the Institute for Advanced Study in Princeton, has confirmed that the idea is on the right track. He showed that the physics inside a hypothetical universe with five dimensions and shaped like a Pringle is the same as the physics taking place on the fourdimensional boundary. According to Hogan, the holographic principle radically changes our picture of space-time. Theoretical physicists have long believed that quantum effects will cause space-time to convulse wildly on the tiniest scales. At this magnification, the fabric of space-time becomes grainy and is ultimately made of tiny units rather like pixels, but a

another. To measure this, the GEO600 team fires a single laser through a half-silvered mirror called a beam splitter. This divides the light into two beams, which pass down the instrument’s 600-metre perpendicular arms and bounce back again. The returning light beams merge together at the beam splitter and create an interference pattern of light and dark regions where the light waves either cancel out or reinforce each other. Any shift in the position of those regions tells you that the relative lengths of the arms has changed. “The key thing is that such experiments are sensitive to changes in the length of the rulers that are far smaller than the diameter of a proton,” says Hogan. So would they be able to detect a holographic projection of grainy spacetime? Of the five gravitational wave detectors around the world, Hogan realised that the Anglo-German GEO600 experiment ought to be the most sensitive to what he had in mind. He predicted that if the experiment’s beam splitter is buffeted by the quantum convulsions of space-time, this will show up in its measurements (Physical Review D, vol 77, p 104031). “This random jitter would cause noise in the laser light signal,” says Hogan. In June he sent his prediction to the GEO600 team. “Incredibly, I discovered that the experiment was picking up unexpected noise,” says Hogan. GEO600’s principal investigator Karsten Danzmann of the Max Planck Institute for Gravitational Physics in Potsdam, Germany, and also the University of Hanover, admits that the excess noise, with www.newscientist.com

frequencies of between 300 and 1500 hertz, had been bothering the team for a long time. He replied to Hogan and sent him a plot of the noise. “It looked exactly the same as my prediction,” says Hogan. “It was as if the beam splitter had an extra sideways jitter.” No one – including Hogan – is yet claiming that GEO600 has found evidence that we live in a holographic universe. It is far too soon to say. “There could still be a mundane source of the noise,” Hogan admits. Gravitational-wave detectors are extremely sensitive, so those who operate them have to work harder than most to rule out noise. They have to take into account passing clouds, distant traffic, seismological rumbles and many, many other sources that could mask a real signal. “The daily business of improving the sensitivity of these experiments always throws up some excess noise,” says Danzmann. “We work to identify its cause, get rid of it and tackle the next source of excess noise.” At present there are no clear candidate sources for the noise GEO600 is experiencing. “In this respect I would consider the present situation unpleasant, but not really worrying.” For a while, the GEO600 team thought the noise Hogan was interested in was caused by fluctuations in temperature across the beam splitter. However, the team worked out that this could account for only one-third of the noise at most. Danzmann says several planned upgrades should improve the sensitivity of GEO600 and eliminate some possible experimental sources of excess noise. “If the noise remains where it is now after these measures, then we have to think again,” he says. If GEO600 really has discovered holographic noise from quantum convulsions of spacetime, then it presents a double-edged sword for gravitational wave researchers. One on hand, the noise will handicap their attempts to detect gravitational waves. On the other, it could represent an even more fundamental discovery.

Such a situation would not be unprecedented in physics. Giant detectors built to look for a hypothetical form of radioactivity in which protons decay never found such a thing. Instead, they discovered that neutrinos can change from one type into another – arguably more important because it could tell us how the universe came to be filled with matter and not antimatter (New Scientist, 12 April 2008, p 26). It would be ironic if an instrument built to detect something as vast as astrophysical sources of gravitational waves inadvertently detected the minuscule graininess of spacetime. “Speaking as a fundamental physicist, I see discovering holographic noise as far more interesting,” says Hogan.

Small price to pay Despite the fact that if Hogan is right, and holographic noise will spoil GEO600’s ability to detect gravitational waves, Danzmann is upbeat. “Even if it limits GEO600’s sensitivity in some frequency range, it would be a price we would be happy to pay in return for the first detection of the graininess of spacetime.” he says. “You bet we would be pleased. It would be one of the most remarkable discoveries in a long time.” However Danzmann is cautious about Hogan’s proposal and believes more theoretical work needs to be done. “It’s intriguing,” he says. “But it’s not really a theory yet, more just an idea.” Like many others, Danzmann agrees it is too early to make any definitive claims. “Let’s wait and see,” he says. “We think it’s at least a year too early to get excited.” The longer the puzzle remains, however, the stronger the motivation becomes to build a dedicated instrument to probe holographic noise. John Cramer of the University of Washington in Seattle agrees. It was a “lucky accident” that Hogan’s predictions could be connected to the GEO600 experiment, he

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MAGIC EYE ® 3D INSTRUCTIONS

www.newscientist.com

Hold the centre of the Magic Eye Image right up to your nose – it should be blurry. Stare as though you are looking through the image. Very slowly move the image away from your face until you begin to perceive depth. Now hold the image still, try not to blink, and the hidden image will magically appear. The longer you look, the clearer the image becomes.

says. “It seems clear that much better experimental investigations could be mounted if they were focused specifically on the measurement and characterisation of holographic noise and related phenomena.” One possibility, according to Hogan, would be to use a device called an atom interferometer. These operate using the same principle as laser-based detectors but use beams made of ultracold atoms rather than laser light. Because atoms can behave as waves with a much smaller wavelength than light, atom interferometers are significantly smaller and therefore cheaper to build than their gravitational-wavedetector counterparts. So what would it mean it if holographic noise has been found? Cramer likens it to the discovery of unexpected noise by an antenna at Bell Labs in New Jersey in 1964. That noise turned out to be the cosmic microwave background, the afterglow of the big bang fireball. “Not only did it earn Arno Penzias and Robert Wilson a Nobel prize, but it confirmed the big bang and opened up a whole field of cosmology,” says Cramer. Hogan is more specific. “Forget Quantum of Solace, we would have directly observed the quantum of time,” says Hogan. “It’s the smallest possible interval of time – the Planck length divided by the speed of light.” More importantly, confirming the holographic principle would be a big help to researchers trying to unite quantum mechanics and Einstein’s theory of gravity. Today the most popular approach to quantum gravity is string theory, which researchers hope could describe happenings in the universe at the most fundamental level. But it is not the only show in town. “Holographic space-time is used in certain approaches to quantising gravity that have a strong connection to string theory,” says Cramer. “Consequently, some quantum gravity theories might be falsified and others reinforced.” Hogan agrees that if the holographic principle is confirmed, it rules out all approaches to quantum gravity that do not incorporate the holographic principle. Conversely, it would be a boost for those that do – including some derived from string theory and something called matrix theory. “Ultimately, we may have our first indication of how space-time emerges out of quantum theory.” As serendipitous discoveries go, it's hard to get more ground-breaking than that. ● Marcus Chown is the author of Quantum Theory Cannot Hurt You (Faber, 2008) Read previous issues of New Scientist at www.newscientist.com/issues/current

17 January 2009 | NewScientist | 27

The acid test Where and how did life begin? Douglas Fox visits a man playing God in a volcanic mud pool

David Deamer thinks hot springs like those in Bumpass Hell, California, hold the key to the emergence of life 28 | NewScientist | 17 January 2009

www.newscientist.com

●

JETS of sulphurous steam roar out of holes in the ground and an eggy stench hangs in the air. This is Bumpass Hell, a valley of bubbling mud pools in the heart of the Lassen Volcanic National Park in northern California. The valley is ringed with beautiful pine and fir trees climbing up the surrounding slopes, but life seems to have stayed away from the lower reaches. Billions of years ago, though, the opposite might have been true. I’ve come to Bumpass Hell with David Deamer, a biochemist from the University of California, Santa Cruz, to watch him run an experiment recreating one of the most important episodes in the history of life: when carbon, hydrogen, oxygen, nitrogen and phosphorus came together in the primordial soup to form amino acids, DNA and the rest of life’s building blocks. If Deamer is right, then the sort of extreme conditions found here were key to that momentous event. It may be an unattractive and rather dangerous place to work, but to Deamer this is one of the most precious places on Earth – the closest thing he can get to the cauldron of chemicals from which life might have emerged over 4 billion years ago. Researchers have spent decades trying to recreate this magical moment in their labs, and they have made some impressive discoveries along the way. In 1953, Stanley Miller, then at the University of Chicago, was the first to synthesise amino acids by passing high voltages through a cocktail of ammonia, methane, hydrogen and water vapour. In the decades that followed, researchers found other ways to synthesise amino acids and nucleotides – the building blocks of DNA and RNA – at temperatures ranging from 80 °C to -80 °C. They also discovered many different ways in which these molecules could assemble into larger structures similar to life’s first proteins and genetic molecules.

JONATHAN SPRAGUE/REDUX

Test-tube life forms

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Deamer is a veteran of such experiments himself. Along with Jack Szostak, a biochemist at Harvard University, he has created test-tube environments in which fatty acids and similar molecules self-assemble into cell-like structures – one of the key steps in the emergence of life. These artificial proto-cells are able to survive boiling (Proceedings of the National Academy of Sciences, vol 105, 17 January 2009 | NewScientist | 29

p 13351) and can absorb nucleotides from the environment as they grow chains of RNA within (Nature, vol 454, p 122). Still, huge gaps remain in our knowledge of how life began. The first genetic material might have been RNA, but equally it might have been some other, unknown molecule. And which of early Earth’s varied environments was the one that first spawned life – did it happen in a deep-sea hydrothermal vent, on frigid polar sea ice or in boiling cauldrons of clay and water like the ones at Bumpass Hell? We just don’t know. Deamer and a few other like-minded researchers have concluded that lab work alone can get them no further. They have decided to find out which of the experiments that work so well in a squeaky-clean laboratory can be reproduced in the messy real world. “The prebiotic world was much more complex than a laboratory situation,” says Deamer. He thinks that doing experiments in places like Bumpass Hell will help narrow down the environments that are realistic candidates for the origin of life. Forget the theory, he says: he wants to see which candidates actually work. It’s all too easy to make a false discovery, however. Even in a thoroughly controlled environment, just a few bacteria creeping into the apparatus undetected can ruin the experiment. You could mistakenly conclude that your chemical soup was generating DNA which had in fact come from these trespassing microbes. To prevent such contamination, Miller baked his glassware near its melting point for up to 24 hours.

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Of course, Deamer can’t do that in his mud pools. But unlike Miller, he has a way of distinguishing between synthesised and bacterial nucleotides and RNA. Deamer adds enough bio-material to swamp any belonging to bacteria by a factor of around 100, which means that any synthesised biomolecules will also swamp any signal of bacterial origin. There is no better way to test if a candidate environment could have led to life on early Earth, he says. Other researchers have tried experiments in cold environments. In 1999, Hauke Trinks, then at the Hamburg University of Technology in Germany, travelled to the Arctic to study the properties of sea ice as an incubator for life. He measured the ice’s ability to trap and concentrate RNA molecules inside microscopic pockets of unfrozen brine (New Scientist, 12 August 2006, p 34). Deamer, on the other hand, thinks life emerged in a very different environment. Bumpass Hell lies near a volcano that last erupted in 1915. The cauldrons that belch 30 | NewScientist | 17 January 2009

JONATHAN SPRAGUE/REDUX

Swamping contaminants

www.newscientist.com

JONATHAN SPRAGUE/REDUX

Extract a sample of clay, add nucleotides (far left) and wait for life to emerge

boiling mud are a potent reminder that the volcano is merely dormant, not extinct. Water from rain and nearby streams continually drains through fissures in the valley to a spot 4 kilometres below the surface, where it meets molten lava and flashes into steam. In the geological equivalent of an espresso machine, the steam hisses back up through cracks – carrying sulphuric acid, smelly hydrogen sulphide, iron and other substances to the surface. The pools are a mess of chemicals, including a lot of sulphuric acid, and the edges of the vents undergo regular cycles of wetting and drying, heating and cooling. Industrial chemists have long known that cycles of drying can help kick-start chemical reactions that don’t work in moist conditions. Deamer thinks these cycles could also drive important biochemical reactions, like RNA synthesis, outside of a cell. RNA, believed to be a precursor to DNA, consists of a chain of small molecules called nucleotides linked together like the carriages of a train. Inside cells, enzymes catalyse the linking process, but RNA chains are difficult to grow under most natural conditions in the absence of enzymes because the chemical bonds between the nucleotides break as easily as they form (it’s the same for other biological polymers, like DNA and proteins). Every time two RNA nucleotides bind together they release a molecule of water as a by-product.

A bubbling valley of mud may seem inhospitable, but some argue this is the kind of place where life began www.newscientist.com

And when two nucleotides split apart they absorb a molecule of water (see diagram). One way to manufacture long molecules like RNA is to get rid of the water that the chain releases as it grows, so that it’s not around to break the bonds after they form. Removing water actually drives the growth of chains by shifting the chemical equilibrium toward forming bonds instead of breaking them. As Deamer puts it, life is basically made by removing water molecules from between nucleotides. A hot place like Bumpass Hell, where water is constantly evaporating, would provide the perfect environment for this. But does Bumpass Hell really reflect conditions on the early Earth? There may be no trees or grass on this infernal ground, but plenty of bacteria live here. Oxygen represents another wild card: 4 billion years ago the atmosphere contained very little of it. Furthermore, the composition of the clay at Bumpass Hell is probably radically different from the mud on early Earth. Robert Hazen, a geochemist at the Carnegie Institution in Washington DC, has constructed a history of what he calls Earth’s mineral evolution (New Scientist, 22 November 2008, p 14). Of the 4400 minerals known today, he estimates that fewer than 1000 existed 4 billion years ago (American Mineralogist, vol 93, p 1693). Volcanic clays like those at Bumpass probably did exist, but their composition was likely very different from what is found today. “The chemistry of [modern] life will affect these experiments, there’s just no way around that,” says Hazen. “It will not be mimicking early Earth.” Despite this, Hazen still sees value in Deamer’s experiments as a filter to identify which of 17 January 2009 | NewScientist | 31

JONATHAN SPRAGUE/REDUX

Cycles of wetting and drying on the edges of boiling mud pools might kick-start key chemical reactions

“As if in a geological espresso machine, steam hisses up through the cracks” the environments that work in the test tube are robust enough to succeed in the more variable conditions that exist outdoors. So what exactly has Deamer found? Suppose that the chemical soup in which life is thought to have arisen on early Earth contained RNA nucleotides or similar molecules. Water that splashed from a boiling pool could deposit these molecules onto dry land, where the water would evaporate. Deamer thinks this would cause the nucleotides to link into short chains of RNA. New splashes of water would deliver a fresh supply of nucleotides, which would grow the chains as they dried. The process might repeat over and over. “Complexity as we know it in life is longer and longer molecules,” says Deamer. So how do you drive that? The most likely way is an environment that cycles between wet and dry, he says. Deamer and others have grown RNA in such an environment in the lab. “That boiling pool over there with wetting and drying around the edges is what we try to simulate in the laboratory,” he says, nodding at a milky yellow 32 | NewScientist | 17 January 2009

mud pot a few metres away. Now he wants to see if those experiments work in the real world. He tests the acidity level of various lumps of clay that he has collected: “That’s almost stomach acid,” he mutters, setting down one of the yellow-white lumps. He then squirts each one with a few drops of liquid, adding nucleotides to some, nothing to others acting as controls, and to yet others he adds RNA – to see whether it can survive the 80 °C temperatures and the concentrated sulphuric acid present in the clay. He then sets them in the opening of a vent to cook.

Life in the gutter This real-world approach is slowly gaining supporters. “These experiments bring something that is sometimes missing in the lab,” says Pierre-Alain Monnard, a biochemist at the University of Southern Denmark in Odense. “I think it could lead to a discovery that no one thought about because we are working in clean environments compared to what life evolved in. We are almost working

in the hospital, and life started in the gutter.” A few weeks after the field trip, Deamer’s preliminary findings are already challenging lab-based results. He now thinks the first chains of RNA may have grown wrapped in blankets of concentrated sulphuric acid. “You remember me kneeling in the clay? The acid was so strong it ate out the knees of my jeans. On the way home both knees fell out.” And yet it seems that, despite the acid and the heat, the nucleotides and RNA Deamer was experimenting with have survived. What’s more, in the lumps of clay to which he added single nucleotides, he now sees what look like chains of RNA. Other clay samples to which he added nothing show no RNA – suggesting the new RNA strands are not the result of contamination. He thinks he can explain how this happened: a film of sulphuric acid must cover the surface of the clay. If concentrated enough, the acid will act as a drying agent, sucking water molecules out of any source that it can – including a growing chain of RNA – just as evaporation would. “It literally pulls water out of the compounds,” says Deamer. In fact, chemists have used sulphuric acid in this way to synthesise organic chemicals in the lab. The idea of sulphuric acid providing a womb for growing fragile molecules of RNA is controversial, since most people would expect the acid to break the RNA chain apart – a process that chemists call hydrolysis. But sulphuric acid is an effective drying agent. Some scientists have even suggested that sulphuric acid rather than water could be a medium for life on other planets (New Scientist, 9 June 2007, p 34). Deamer needs to re-analyse his samples to confirm that he really did grow RNA inside the clay. But already he is ploughing ahead with lab experiments to grow RNA in sulphuric acid, the way he thinks happened at Bumpass Hell. He also hopes to sample other types of hot springs. Top of his list is the silicon-rich environment around the volcanoes of Hawaii. Many more independent trials and lab experiments will be needed to determine if his conclusions are correct, but if his idea about the role of sulphuric acid proves true, it will provide a completely new view of the origin of life on Earth. “That’s the kind of thing that only happens if you actually go out in the field and try these things,” he says. ● Douglas Fox is a writer living in northern California www.newscientist.com

●

GERHARD HUMMER was pondering a serious plumbing problem. He was trying to unravel the inner workings of tiny proteins called aquaporins, which are found in the walls of living cells. Each aquaporin is threaded by a narrow pore that helps control the flow of water into the cell. The pore is a complex thing, narrow in parts and wide in others, lined with a variety of chemical groups that mostly repel water. But it is basically a pipe. And that realisation made Hummer, working at the US National Institutes of Health in Bethesda, Maryland, turn his attention to carbon nanotubes. Consisting of curled-up sheets of carbon and just nanometres wide, they are essentially smooth pipes of water-repelling graphite. Hummer hoped that their simple structure might offer new insights into the way that water travels through aquaporins. It proved a smart move. Nanotubes have not only helped researchers like Hummer understand water flow in

proteins, but they are also enabling scientists to devise a host of nanoscale plumbing parts – such as molecular pumps, gates and valves – capable of moving and filtering everything from salty water and hydrocarbon fuels to gases such as carbon dioxide. It seems that these humble tubes could hold the key to cheap desalinated water, better fuel cells and new strategies to tackle global warming. Hummer’s study of fluid flow in nanotubes kicked off around a decade ago when along with two colleagues he created a detailed computer simulation of the way water moves inside a carbon nanotube just 0.8 nanometres wide. When they dunked the tube into a tiny tank of virtual water, the researchers found that a thin thread of water molecules rushed into the interior of the tube. This was surprising, given the narrowness of the nanotube’s pore and the water-repelling nature of its carbon surface. Then when they tweaked the simulation, slightly increasing the repulsion between the water molecules

Build nanotubes in the right way and they’ll work tirelessly to filter our water and clean up our air – and much more besides. Philip Ball reports

MARTIN KLINNAS/FANCY/JUPITER

Cunning plumbing

www.newscientist.com

17 January 2009 | NewScientist | 33

JOSE LUIS ROCA/AFP/GETTY

Nanotubes could make desalination plants far more efficient, cutting the cost of fresh water

and the carbon atoms of the nanotube, they were surprised to see that the tube emptied almost instantaneously. When they decreased the strength of the repulsion, the tube filled again. The ease with which they could fill or empty the tube was unexpected, and their results – published in Nature in 2001 (vol 414, p 156) – implied that just small changes in charge or even tube geometry might be used to move water through real nanotubes. Hummer and his colleagues then simulated an array of short carbon nanotubes, again each one just 0.8 nanometres across, packed side by side in a membrane. When pure water was added to one side of the membrane and brine to the other, water immediately flowed down the nanotubes into the brine, driven by the difference in salt concentration. What surprised the researchers was the speed of the flow: it seemed that the chain of water molecules passing through each nanotube experiences virtually no friction, moving nearly ten thousand times faster than theory predicts. What’s more, Hummer’s team found that ions could not get through the pores in either direction. In principle, the nanotubes were wide enough to let the ions through, but it seems they could not make it when the water was confined by the tube. The reason for this behaviour is actually straightforward (see diagram). Charged ions, like those in brine, are surrounded by a network of water molecules in a so-called “hydration shell”. But there is no space to accommodate this network inside a nanotube. Instead, each water molecule is hydrogen-bonded to just two others, one in front and one behind, 34 | NewScientist | 17 January 2009

forming a continuous, organised chain. For an ion to enter a nanotube, its hydration shell must be stripped away. Hummer’s results suggest this costs too much energy, so the ions stay put. This, in effect, is what occurs in a conventional desalination process called reverse osmosis in which brine is filtered by a fine membrane so that pure water passes through and the ions are left behind. However, this process requires large amounts of energy to pump the water through the membrane, which is one reason why desalinated water is expensive. The high flow-rates measured by Hummer suggested that desalination would be more efficient if it could harness the ionblocking properties of nanotube membranes.

Super-fast flow Constructing membranes from parallel nanotubes is a huge technical challenge. But it can be done: in 2006, Olgica Bakajin of the Lawrence Livermore National Laboratory in California and her co-workers grew nanotubes with inner diameters of about 1.6 nanometres, organised in a parallel arrangement, like the pile in a carpet. Then they embedded the nanotubes in a thin but strong film of the ceramic silicon nitride (Science, vol 312, p 1034). In experiments, these membranes permitted much the same superfast water flow as Hummer had observed – the water rushed through the nanotubes up to 100 times as fast as through conventional porous membranes with far wider pores. Yet the nanotubes must be even narrower if they are to be effective for desalination. With a diameter of more than 1 nanometre,

ions can start to sneak through, says Hummer. “Keeping the pore diameter below this value is important for efficient salt exclusion,” he says. According to a recent paper in the Journal of Physical Chemistry B (vol 112, p 1427) by Ben Corry at the University of Western Australia in Perth, nanotubes measuring 0.93 nanometres across block out 95 per cent of ions. This is good enough to make drinking water, and such a membrane should perform around five times as efficiently as current designs, purifying tens of thousands of litres per square metre per day, Corry says. Corry is now collaborating with chemists to construct nanotube arrays in an altogether different membrane structure. He reckons that silicon nitride is too brittle to be useful, so he is trying to embed the nanotubes in flexible polymers like the polycarbonates used in conventional desalination membranes. Hummer is hopeful that such efforts will pay off. “This is a rapidly evolving field,” he says. “I am quite optimistic that densely packed, narrow nanotube membranes can be made, and will be made soon.” In some water-purification applications, it would also be useful to have control over the flow through the narrow channels: to be able to turn it on and off as required, for example. For tricks like this, researchers are again turning to nature for inspiration. Take the membrane protein MscS, which controls the transport of ions in bacteria. MscS contains a water channel about 1 nanometre wide that can be closed by stretching the cell membrane in which the protein sits. This distorts the protein, and constricts the pore just enough to keep water out. www.newscientist.com

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Engineers are starting to wonder if they can mimic this behaviour in water-filtration membranes by adding chemical groups to carbon nanotubes to create valves and filters. “Clearly, biology provides an amazing array of nanoscale solutions, including those for gated flow,” says Hummer. He admits that it is hard to tamper with the rather inaccessible surface inside a nanotube. “But a lot of interesting chemistry has already been done at the rims.” Bruce Hinds and his colleagues at the University of Kentucky in Lexington have begun to explore the idea of controllable nanotube membranes. They have taken advantage of the reactivity of carbon atoms at the ends of the nanotube to tether a small organic molecule called a biotin. Biotin, also known as vitamin B7, selectively binds to a protein called streptavidin, and when the nanotubes in the membrane are exposed to a solution of streptavidin, the protein sticks to the openings, reducing the flow to just one-fifteenth of its former rate. Hind’s team is now exploring more sophisticated ways of adding gates. For instance, they have grafted an electrically charged molecule onto the mouth of a tube. Applying an electric field to the nanotube moves the molecule into the entrance, obstructing fluid flow. They have even created a gate made from a synthetic peptide that can be closed by a molecule of ATP, the energy-carrier in human cells. The ATP triggers a reaction in which a large antibody binds to the peptide, blocking the pore. This gating method was inspired by the kinds of chemical switches used to control ion flow and other processes in cells, says Hinds. He suggests that it might also be www.newscientist.com

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possible to use ATP or other energy sources to power a molecular motor at each nanotube’s entrance to pump fluid through. This would be an important step towards a nanoscale desalination system, says Hinds. Haiping Fang and his colleagues at the Shanghai Institute of Applied Physics in China are already moving towards this goal. In simulations published in Nature Nanotechnology (vol 2, p 709) in November 2007, they showed that three positive charges placed outside a carbon nanotube at specific points along its length can pull water molecules through the tube in one direction. These could be provided by charged groups attached to the outside of the nanotube – which is much easier to modify than the inside – or even by small electrodes . The asymmetry of the charge distribution is what causes a preference for flow in one direction. The design mimics the way charged amino acid groups are arranged in the water channel of aquaporins, Fang points out.

Electric nanopump Though still purely theoretical, this nanopump works thanks to the charge distribution on water molecules as they line up inside the narrow channel. The pump would not require any external pressure to drive the water through, and combined with the salt-excluding properties of nanotubes, it would offer a simple nanoscale desalinator. Yet it will require a source of energy to run, because energy is needed to hold the charges in place: water molecules moving through the channel will exert a force on them, and

try to drag them out of position as they pass. The precise positioning and control of the charges will be difficult, Fang admits, but he hopes to find experimentalists who are up for the challenge. If they succeed, these gates and pumps could be useful in all kinds of ways. Hummer, for example, envisages using nanotubes as channels, gates, valves and pumps in nanofluidic circuits. These could move tiny quantities of chemical solutions around on chip-sized devices for medical and environmental diagnostics. They might also be useful for extracting or transporting hydrogen ions, perhaps to increase the efficiency with which fuel cells generate energy. Modifications of the nanotubes at the insides or ends will be the best way to produce controllable gating and filtration, says Bakajin. “We’ll eventually use the nanotubes as the highways, and we will use some kind of gate at the end that blocks whatever it is that we want to exclude.” Bakajin has also discovered that her nanotube membranes can transport gases as well as liquids, and will selectively admit smaller molecules like hydrogen and nitrogen rather than carbon dioxide. “By modifying the chemistry of the pore it may be possible to make this differentiation much greater and to target it so that the membranes can be used for molecular separation or molecular sensors,” Corry says. Eventually, it might be possible to build nanotube membranes that can separate mixtures of hydrocarbon gases, filter CO2 from a power plant chimney, say, or even extract the gas directly from the air. ● Philip Ball is a consultant at Nature 17 January 2009 | NewScientist | 35

Is sadness an essential human emotion or is it time to banish it for good, asks Jessica Marshall

Woes be gone ●

WHY be miserable? OK, so it’s January and you’re feeling fat and broke after the excesses of the holiday season, but there’s really no need. Misery is inconvenient, unpleasant, and in a society where personal happiness is prized above all else, there is little tolerance for wallowing in despair. Especially now we’ve got drugs for it. Antidepressants can help banish sad feelings – not just the life-sapping black dog of clinical depression, but the rough patches that most people go through sometimes, whether it’s after losing a job, the break-up of a relationship or the death of a loved one. So it’s no surprise that more and more people are taking them (see graph, page 39). But is this really such a good idea? A growing number of cautionary voices from the world of mental health research are saying it isn’t. They fear that the increasing tendency to treat normal sadness as if it were a disease is playing fast and loose with a crucial part of our biology. Sadness, they argue, serves an evolutionary purpose – and if we lose it, we lose out. “When you find something this deeply in us biologically, you presume that it was selected because it had some advantage, otherwise we wouldn’t have been burdened with it,” says Jerome Wakefield, a clinical social worker at New York University and co-author of The Loss of Sadness: How psychiatry transformed normal sorrow into depressive disorder (with Allan Horwitz, Oxford University Press, 2007). “We’re fooling around with part of our biological make-up.”

36 | NewScientist | 17 January 2009

Perhaps, then, it is time to embrace our miserable side. Yet many psychiatrists insist not. Sadness has a nasty habit of turning into depression, they warn. Even when people are sad for good reason, they should be allowed to take drugs to make themselves feel better if that’s what they want. So who is right? Is sadness something we can live without or is it a crucial part of the human condition? Hard evidence for the importance of sadness in humans is difficult to come by, but there are lots of ideas about why our propensity to feel sad might have evolved. It may be a self-protection strategy, as it seems to be among other primates that show signs of sadness. An ape that doesn’t obviously slink off after it loses status may be seen as continuing to challenge the dominant ape – and that could be fatal. Wakefield believes that in humans sadness has a further function: it helps us learn from our mistakes. “I think that one of the functions of intense negative emotions is to stop our normal functioning, to make us focus on something else for a while,” he says. It might act as a psychological deterrent to prevent us from making those mistakes in the first place. The risk of sadness may deter us from being too cavalier in relationships or with other things we value, for example. What’s more, says Paul Keedwell, a psychiatrist at Cardiff University in the UK, even full-blown depression may save us from the effects of long-term stress. Without taking www.newscientist.com

time out to reflect, he says, “you might stay in a state of chronic stress until you’re exhausted or dead”. He also thinks that we may have evolved to display sadness as a form of communication. By acting sad, we tell other community members that we need support. Then there is the notion that creativity is connected to dark moods. There is no shortage of great artists, writers and musicians who have suffered from depression or bipolar disorder. It would be difficult to find enough recognised geniuses to test the idea in a large, controlled study, but more run-of-the-mill creativity does seem to be associated with mood disorders. Modupe Akinola and Wendy Berry Mendes of Harvard University found that people with signs of depression performed better at a creative task, especially after receiving feedback that was designed to reinforce their low mood. The researchers suggest that such negative feedback makes people ruminate on the unhappy experience, which allows subconscious creative processes to come to the fore, or that it pushes depression-prone people to work harder to avoid feeling bad in the future (Personality and Social Psychology Bulletin, vol 34, p 1677).

Don’t be happy, worry There is also evidence that too much happiness can be bad for your career. Ed Diener, a psychologist at the University of Illinois in Urbana-Champaign, and his colleagues found that people who scored 8 out of 10 on a happiness scale were more successful in terms of income and education than 9s or 10s – although the 9s and 10s seemed to have more successful close relationships (Perspectives on Psychological Science, vol 2, p 346). This could simply demonstrate that the happiest people are those who cherish close relationships over power and success, but it could also signal that people who are “too happy” lose their willingness to make changes to their lives that may benefit them. Medicating sadness, Keedwell suggests, could do the same – blunting the consequences of unfortunate situations and removing people’s motivation to improve their lives. Giving antidepressants to people whose real problem is something else – a bad relationship, for instance – may allow the person to continue in an unhealthy situation instead of addressing the underlying problem. Whether or not a little sadness is useful, everyone agrees that clinical depression is not. Unfortunately it’s not clear exactly where to draw the line between the two (see “Sad or depressed?”, page 39). So which is more dangerous: to over-medicate normal sadness, a feeling which may lead us to re-evaluate our lives after the loss of a www.newscientist.com

17 January 2009 | NewScientist | 37

“Should we use pills

to speed up our emotional journey back to happiness? ”

job or the end of a relationship, or undermedicate clinical depression? Ian Hickie of the Brain and Mind Research Institute at the University of Sydney, Australia, insists that depression is not overdiagnosed but would rather it were than see seriously depressed people left out in the cold. He points out that there is evidence to suggest that the number of suicides has declined as more cases of depression have been diagnosed. It’s important to take borderline diagnoses of depression seriously, he says, because “most of the suicides do not occur in the most severely depressed”. Wakefield, however is uneasy about prescribing pills where there is no certainty that they are needed. After all, he points out, antidepressants have side effects, some of them serious.

The need for sad

A pill for every ill When the first antidepressant came to market in the 1950s, the company that marketed it did not think there were enough depressed people for the drugs to make a profit. By 2000, though, antidepressants were a $7 billion business in the US alone. Outpatient treatment for depression increased threefold between 1987 and 1998. Many people blame the pharmaceutical industry for huge increases in the number of depression diagnoses, especially in countries like the US where drug companies can advertise their products directly to consumers on television, radio and in magazines. One recent study by Richard Kravitz at the University of California, Davis, aimed to test this idea. Kravitz sent actors into doctors’ offices. Half presented symptoms of depression, half did not. Each actor either asked for the antidepressant Paxil specifically, asked for help from a drug without specifying which one they wanted, or made no request. Those who asked for a drug were more likely to get one than those who did

38 | NewScientist | 17 January 2009

not request medication, whether or not they had symptoms of depression (The Journal of the American Medical Association, vol 293, p 1995). Gordon Parker of the Black Dog Institute in Sydney, Australia, also points out that the drug industry has benefited from the somewhat broad definition of depression. “Having a lack of precision has made it absolutely appropriate for the pharmaceutical industry to say, ‘We’re just treating this broad, generic condition,’” he says. Others are not so convinced that patients are being led towards a decision. “One view is that this is being marketed by the doctors and the pharmaceutical industry. I think that misses the argument that people themselves are much more interested in having a better life,” says Ian Hickie of the Brain and Mind Research Institute at the University of Sydney. “People are always looking to enhance themselves. I don’t think clinical depression is a lifestyle issue. It’s just like surgery being a serious thing, but that doesn’t stop the cosmetic surgery industry.”

So where does this leave the notion of human sadness? Should we accept that major life events may make us so sad that we are temporarily disabled? Or should we run to the doctor in the hope that pills will speed up our emotional journey back to happiness? Ken Kendler, a psychiatrist at the Virginia Commonwealth University in Richmond, points out that for some people, sadness is definitely something they are better off without. He recalls a mother in her late 20s who came to him because she had an inoperable defect in her aorta that would rupture at some undeterminable time in the future, killing her instantly. This knowledge had made her depressed – certainly with reasonable cause – but she did not want to live the rest of her days that way, unable to function for her family. “That seemed to me to be an irreproachable logic on her part,” Kendler says. “I started her on antidepressants. She came back much brighter. The idea that I was depriving this woman of the proper grieving experience and preventing her from experiencing deeply the meaning of this rang very hollow in this particular case.” For those of us not faced with such an extreme problem, Terence Ketter, a psychiatrist at Stanford University in California, is more cautious. “The cost of happiness is complacency,” he says. Sadness is still something useful: “Discontent can drive change. Certainly, you don’t want to stifle or blunt emotion – emotion is information.” Keedwell agrees. “Clearly, if we didn’t feel sad when we were unsuccessful at achieving certain goals, we would not stand back from that goal and introspect and perhaps try to change our strategies,” he says, echoing Wakefield and the Harvard creativity study. www.newscientist.com

Sad or depressed? If you have experienced five of the symptoms below for two weeks or more, including at least one of the first two, you meet the diagnostic criteria for major depressive disorder. Depressed mood Reduced interest or enjoyment in normal activities ● Loss or gain of weight or appetite ● Insomnia or excessive sleep ● Fatigue or loss of energy ● Feelings of worthlessness, or excessive or inappropriate guilt ● Indecisiveness or reduced ability to concentrate ● Agitated motion like pacing or handwringing, or physical slowing down ● Thoughts of death or suicide ● ●

This definition, introduced in the third edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-III) in 1980, changed the definition of depression from something that depended on the context of an individual’s life circumstances to a more objective list of symptoms. There is one notable caveat.

According to the DSM criteria, if you have these symptoms after the death of a loved one you are not considered to be depressed, but suffering a normal reaction to bereavement. Some, however, say that bereavement isn’t the only type of grief that should be left out of a diagnosis of depression. Jerome Wakefield of New York University is one of them. He says that other losses, like divorce, illness or loss of a job, should also exempt people from a diagnosis of depression because these unhappy but commonplace events can trigger similar symptoms. “It does make one worry that any negative emotion [except the grief of bereavement] that disrupts your ability to function in a happy manner could be classified as a disorder,” he says. In a study published in 2007, Wakefield’s team reported on more than a thousand people who met the criteria for major depressive disorder, some of whose episodes were triggered by “standard” bereavement and others whose depression was triggered by another loss. They found that the depression they suffered was very similar. “That suggested that about

25 per cent of people who would be diagnosed in the community as being depressed are probably actually suffering from normal reactions,” Wakefield says. Moreover, the symptoms of those who were grieving for reasons other than bereavement were indistinguishable from those of the bereaved (Archives of General Psychiatry, vol 64, p 433). Wakefield says this means that other forms of normal sadness should be exempted from the DSM criteria. Other researchers, though, feel the opposite is true: that far from being excluded, anything that creates depressive symptoms – grief included – should be diagnosed as clinical depression and treated accordingly. Ken Kendler at the Virginia Commonwealth University in Richmond, for example, carried out a similar study to Wakefield’s but drew the opposite conclusion. He compared individuals with bereavement-related depression with those depressed because of other stressful events. He found that there were few differences in symptoms between the groups. “Bereavementrelated depression often is recurrent, genetically influenced, impairing, and

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treatment-responsive,” he writes – not just something that everyone goes through (The American Journal of Psychiatry, vol 165, p 1449). With the next edition of DSM due in 2012, the debate is likely to hot up over the next couple of years. For some, however, the problem isn’t just about exemptions, it is also about setting the bar too low. For Gordon Parker, a psychiatrist and executive director of the Black Dog Institute in Sydney, Australia, making a diagnosis of depression easier to reach isn’t helpful. “[It] has taken psychiatry into the dark ages,” he says. In his view, there’s no use in having a definition of depression that is broad and devoid of context. “Say you go along to your general practitioner and he says, ‘I know what you’ve got. You’ve got major breathlessness.’ You’re not going to be very impressed. You want to know whether you’ve got pneumonia or asthma, or a pulmonary embolus, because you then know that the treatment will be rational. If you go with a generic diagnosis, how can you possibly work out what is the key, underlying pathology?”

“Being enthusiastic and jubilant we would probably go blindly on.” So is there some middle ground? Both sides agree that there are ways to lift the gloom without pills. “An alternative would be thinking about what is making you unhappy,” says Wakefield. “Another possibility is watchful waiting. A more nuanced view of the situation will help people think about their options better.” Diener also suggests we stop obsessing about being happy all the time (see “A pill for every ill”, page 38). “One of the things we want to do is disabuse people of the notion that they’re not happy enough,” he says. He cites a study that used emotion-recognition software to work out the Mona Lisa’s inner feelings (New Scientist, 17 December 2005, p 25). It concluded that she is 83 per cent happy. The rest is a mix of negative emotions like fear and anger. That, it seems, is just about right. ● Jessica Marshall is a freelance science writer based in St Paul, Minnesota Read previous issues of New Scientist at www.newscientist.com/issues/current

17 January 2009 | NewScientist | 39

Perspectives

A proper study of mankind... ■

Ever since hunter-gatherers decimated mammoth populations and used fire to create favourable landscapes, people have changed the face of the Earth. Now there is a new twist. Reports from the Intergovernmental Panel on Climate Change (IPCC) leave no wriggle room: humans are a force of nature, capable of altering, probably irreversibly, the surface of the Earth, its flimsy troposphere and its ozone layer – the conditions in which we have evolved and on which our further existence is predicated. Crop pollination, food, drinking water, stable climate and everything else that sustains the web of life on which we and other life forms depend are vulnerable to collapse through these anthropogenic changes. For those from an Enlightenment tradition who believe in the human ability to develop knowledge to make the world a better place, this raises big questions. Can we adapt tools forged to create wealth and use them for sustainable development? Is ever-increasing wealth the only viable measure of progress? Is it possible to have global governance that protects our future? Can individuals really be rational and modify behaviours accordingly? I was brought face to face with these issues over 18 months spent as one of many authors working on the report of the International Assessment of Agricultural Knowledge, Science and Technology for Development

Profile Niels Röling is an emeritus professor of communication and innovation studies at Wageningen University in the Netherlands. Among his interests are policies and strategies for fostering innovation in subsistence farming.

40 | NewScientist | 17 January 2009

(IAASTD), which set out to assess how agriculture might help to feed the world without destroying it. It brought together scientists, farmers, industry, government, NGOs and others in an unprecedented dialogue. Unsurprisingly, the parties found it hard to listen to each other. One of the things this exercise brought home to me was how poorly we understand humans as agents of planetary change, how little of what we do know is widely shared, and that this knowledge is scattered across disciplines that appear distant to governance. I began to ask if we needed a new discipline, one that could go beyond the work of thousands of ecologists, climatologists, economists, anthropologists, psychologists, political scientists, neuroscientists and the like. I decided to appropriate the name “anthropogenics” for my dream discipline, although I gave the word a broader remit than the adjectival dictionary entry I found, which relates to “environmental pollution and pollutants originating in human activity”. My anthropogenics would be an “adaptive” science, in that it would focus on a more effective and less destructive coupling of humans and their environment, while its study of behavioural and social dynamics would be concerned with drivers such as an awareness of interdependence in resource use, rather than individual greed. Anthropogenics would also be a praxiology – a science that informs decisions and action. Crucially, it would only work well as a truly democratic science, shaped not only by academics but by all who have to live by it. From where we are now this may sound idealistic, but the Climate Change Knowledge

ZONE 5/REX FEATURES

Humans have become a force of nature. Whether this turns out to be truly terrifying depends on finding out how such a force might be harnessed, says Niels Röling

Network in the Netherlands is a good example of how such involvement can work. Here, city engineers, spatial planners, water authorities, local governments, city and business groups, and individuals, who used to operate on their own, have recognised that they need to work closely together to understand and mitigate the vulnerability of the low-lying Netherlands to climate change. At the heart of anthropogenics, then, would be a synthesis of what we know about our ability to sacrifice private for public good, to take less and give more, and of research into game theory, social psychology, anthropology and evolutionary economics. It will challenge the key western assumption that human behaviour is necessarily selfish. A close understanding of how institutions determine individual behaviour might even curb the enthusiasm for “methodological www.newscientist.com

showed that human societies can create institutions to manage collectively competing claims on common resources. Underlying such institutions is an acute awareness that individuals can only reach their particular goals if others can reach theirs. The centrality of interdependence is a good example of why anthropogenics would be an adaptive science: ecological imperatives inform the behavioural outcomes and vice versa. The question is whether agreements like these can also be made in more complex societies, and in a world in which a handful of countries are disproportionately responsible for climate change. We also need to learn how to manage common resources sustainably. Perhaps the contours of anthropogenics become clearer if we compare our response to climate change with the way we tackle dangers to our health. Understanding chronic diseases,

“The basis is still selfinterest, but collective not individual”

individualism”, the tendency to explain collective things such as the marketplace as a necessary outcome of individual choices. The explanations generated by my new baby would inevitably differ markedly from those of existing research because they would not be based solely on innate behavioural and social variables but on human behaviour in context. Norms of behaviour, organisations, laws and the extent to which we unwittingly subscribe to a competitive society are all examples of institutional choice and design. Yet the current institutions we appear to have such difficulty giving up clearly do not serve the long-term goals of human survival. The underlying basis of anthropogenics is still self-interest – but of a collective rather than individual kind. Serving a collective selfinterest is not as outlandish as our self-image makes us believe. Admittedly, game theory’s www.newscientist.com

Beautiful but environmentally deadly objects of desire are going to be hard to give up

prisoner’s dilemma scenario appears to show we often opt for short-term, individual gain, even if everyone would be better off long-term by cooperating. But much research challenges such a simplistic reading. Take the famous 1981 paper The Evolution of Cooperation by political scientist Robert Axelrod and evolutionary biologist William Hamilton, in which they showed there was plenty of scope for cooperation under a variety of conditions. The assumption that “rational choice” always leads to self-interested actions also underlies the “tragedy of the commons”, the prediction that common resources such as planet Earth will inevitably be degraded and destroyed. Elinor Ostrom at Indiana University, Bloomington, and others

such as lung cancer, where risk factors are affected by behaviour, is the task of biology. Epidemiology establishes the prevalence of behaviours such as smoking, while social science studies the cultural, behavioural and social dynamics that lead to risky behaviours so we can intervene through laws, education and so on. Epidemiologists and clinicians then assess the impact of our interventions. Climate change has successfully put anthropogenic change on the global agenda, resulting in demands to cut greenhouse gas emissions. But this is like calling for bans on smoking, or issuing warnings about overeating or having unprotected sex, without taking into account the human or social dimensions. How can we ask the world to, say, give up flashy gas guzzlers if we don’t understand the complex interplay between the psychology/ physiology of car ownership and driving or the economic, social and psychological effects of stopping a region from making gas guzzlers? Global society is structured to support unsustainable exponential growth rather than the adaptive, cyclic management of ecological processes. The transformation of the resulting edifice and of the livelihoods of millions dependent on it may be too much for the deliberative process that anthropogenics assumes will occur. But we don’t know. The IPCC has done its job. Now we have to find out whether we can do something about its conclusions by understanding our human reach – and whether we can curb it. ● 17 January 2009 | NewScientist | 41

Review

WHERE IN THE WORLD IS THE MIND? ■

THE mind-body problem is about where the mind is located. Is it bound by the confines of our skull or does it lurk nearby, non-physically? The latter idea, that the mind is not literally in space but is located “near to”, or even “right next to” the body – a halo-like master of ceremonies circumnavigating the head – is metaphysically weird but popular. As recently as 1949, the philosopher Gilbert Ryle insisted that this notion of the “ghost in the machine” was the official view among most laypersons, scientists and intellectuals. How a mind lacking mass, longitude and latitude could be “in” or “near” the particular body whose experiences it is supposed to have, and whose actions it is supposed to initiate, remains mysterious. Still, despite a certain occult je ne sais quoi feel, this view seems intuitive in a plebeian, man-on-the-Clapham-omnibus way. When I try to remember how to get to New York’s Museum of Modern Art from the corner of Broadway and 42nd Street, it seems as if my mind asks my brain, which is nearby, and my brain, which stores addresses, fetches the address and passes it to “me” (“I” live where my mind lives, not where my brain is housed). Let’s call this picture of the mind’s whereabouts Nearby: the mind is not in the brain or in the body, but it is close. By the mid-1950s, though, philosophers with apocryphal42 | NewScientist | 17 January 2009

sounding surnames like Smart (Jack) and Place (Ullin) had articulated an alternative to this unstable view: the mind is the brain. The mind isn’t in the brain in the metaphorical way that my beloved has a “place” in my heart. The mind is literally, physically in the brain because, well, that’s where it is and that’s where it was all along. When I try to remember where the MoMA is, my brain’s prefrontal cortex initiates a “fetch” request to my memory, which passes the information back to the prefrontal cortex, which in turn slides the retrieved info over to the motor cortex, and I am on my way. In his brilliant new book, Supersizing the Mind, Andy Clark calls this view, which holds sway among the neurocognoscenti, Brainbound. Even though Nearby

“Minds are smeared over more space than neuroscience would have us believe” still has the mother lode of fans among the hoi polloi, the problem of the mind’s location has, at least among the experts, been solved. Mind is Brainbound. Or so it seemed. Now a few edgy cognitive scientists and philosophers, including Clark and Alva Noë, claim that both Nearby and Brainbound get the location wrong. There is a third place where the mind might roam. The

theory Clark calls Extended says that the mind is in space, as all sensible naturalists claim, but is smeared over more than brain space. “Certain forms of human cognizing include inextricable tangles of feedback, feed-forward and feed-around loops: loops that promiscuously criss-cross the boundaries of brain, body and world,” he writes. Think about it: when you walk to the MoMA, the you-walkingto-the-MoMA is cognitive, intentional and mindful. But the walking is not in your head – it extends into the world. Walking, talking and seeing are all things the enactive, embodied, extended (code words for this hip new view) mind does in the world. Ironically, dualists, the advocates of Nearby, got the smeariness of mind right. Their mistake was thinking that the smeariness and neariness of mind meant that mind was in no space at all, metaphysically out of this world. According to Extended, the mind is in space and explained entirely by physical processes, but is not confined to the brain. The thesis of the extended mind, according to philosopher Dave Chalmers who offers a terrific introduction to Clark’s book, is that “when parts of the environment are coupled with the brain in the right way, they become parts of the mind”. Suppose Owen is reliably challenged when it comes to remembering addresses, so he always writes important ones

HUGH KRETSCHMER/STONE+

Most scientists subscribe to the idea that the mind is the brain. Now two books argue that the mind is something bigger, extending to the body and leaking out into the world. It is a controversial but convincing idea, says Owen Flanagan

down in his notebook. Owen is in Times Square on his way, again, to the MoMA. When he forgets its address, he consults his notebook in just the way others would activate a “fetch” request to memory. Extended says that the notebook – or the Owen-notebook coupling – counts as part of the cognitive process that reliably results in Owen’s getting to where he wants to go. The Owennotebook coupling is functionally equivalent to the Owen-internal memory coupling that Owen might have used, once did use, and so on. The idea ramifies. Is Extended true? Noë is convinced. His little book Out www.newscientist.com

Bookends

of Our Heads is a desultory hodgepodge of occasionally interesting but perfectly familiar ideas: that the mind is an active rather than passive spectator, that we are fully embodied, and that the mind has all sorts of causes and effects outside of the body. Armed with these plausible ideas, Noë takes aim at Brainbound. He writes: “The fundamental assumption of much work on the neuroscience of consciousness is that consciousness is, well, a neuroscientific phenomenon. It happens inside us, in the brain.” Noë, instead, promises to show that “consciousness does not www.newscientist.com

happen in the brain”. But he never even tries to show such a thing, nor could he if he had tried. The thesis that consciousness “does not happen in the brain” is a much stronger and less plausible thesis than Extended, which Clark is careful to say is a thesis about cognition, thought and mind – not about experience. Clark is careful in a way Noë is not with the consciousness-cognition distinction. Cognition is about thought processes; consciousness is about experience. And experience, as far as we know, is Brainbound or at least “organismbound”. Experiences, at the moment anyway, supervene

only on bodies that house biofuelled nervous systems. But cognition already roams more widely. In our age of cognizing machines, the reach of cognition, outside small circles of homo- or animal-chauvinists, is known: cognition extends beyond human and animal minds. Once we entertain the Extended thesis, likely suspects of extended cognition begin to abound. Take the fascinating research on gesturing, for instance, which suggests that gesturing is not only causally relevant to thoughts, but constitutive of the thinking process itself. Supersizing the Mind provides the best argument I’ve seen for the idea that minds are smeared over more space than neuroscience might have us believe, and that mind will continue spreading to other nooks and crannies of the universe as cognitive prostheses proliferate. The pay-off for thinking in accordance with Extended is a better understanding of mind and a roomier division of intellectual labour among cognitive scientists. “To unravel the workings of these embodied, embedded, sometimes extended minds, requires an unusual mix of neuroscience, computational, dynamical, and informationaltheoretic understandings, ‘brute’ physiology, ecological sensitivity, and attention to the stacked designer cocoons in which we grow, work, think, and act,” Clark writes. The lesson is that despite a consensus that the mind is in the world, we don’t yet know exactly where in the world it is. Still roaming after all these years. ● Supersizing the Mind: Embodiment, action and cognitive extension by Andy Clark, Oxford University Press, $35, ISBN 9780195333213 Out of Our Heads: Why you are not your brain, and other lessons from the biology of consciousness by Alva Noë, Farrar, Straus and Giroux, $25, ISBN 9780809074655 Owen Flanagan is a professor of philosophy and neurobiology at Duke University in Durham, North Carolina

Front-line climate Forecast by Stephan Faris, Henry Holt, $25, ISBN 9780805087796 Reviewed by Gaia Vince

Forecast’s great strength is in recognising that while climate change is a serious stressor, it is just one more factor in the complex interplay of social, economic and political influences on a community. Stephan Faris’s engaging, thoroughly researched reportage takes first-hand examples from Mexico to Bengal, Canada to Russia. He elegantly negotiates the tricky line between the personal and political, and in doing so provides a more accurate and powerful warning about the perils of climate change than many other books in the genre.

Mysterious trinity Is God a Mathematician? by Mario Livio, Simon & Schuster, $26, ISBN 9780743294058 Reviewed by Sam Kean

THEOLOGIANS have God, philosophers existence, and scientists mathematics. Mario Livio makes the case for how these three ideas might be related. He doesn’t give definitive answers, but lays out what Archimedes, Newton, Gödel and others discovered about maths, nature and the design (if any) of the cosmos. He is interested too in the old debate about whether humans discover mathematical theorems that already exist, or merely construct a logical, selfconsistent system. Livio’s rich history gives the discussions human force and verve.

17 January 2009 | NewScientist | 43

Commentary

THEA BRINE

Mindfields A. C. Grayling

Lessons from the world’s wild web SPEECH, drawing, writing, mathematics, printing, photography, telegraphy, film, radio, television, internet: each of these represents a seminal stage in the history of information transfer and a quantum leap in power and range. The gaps between stages have shortened from millennia to decades to years as the curve depicting the speed of development rises ever more steeply. The extent to which the internet will change human society and experience is still unclear, although many of the changes it has already produced are now commonplaces – even necessities – of daily life, such as

pupils. There are serious disadvantages, such as the lack of one-on-one teacher-pupil engagement, but mixing online with traditional education can reduce that problem. The internet will also be one major way of delivering “digital immersion learning”. This is learning that uses virtual reality technology to give students a sense of being realistically inside an environment, so that they can learn more directly by participation. They can “experience” historical events and fly like a bird over continents, through planetary systems or into cells and molecules. Before the internet can be confidently used as an educational tool, however, some of its more serious problems must be addressed, chief among them the unreliability of so much of the information it contains. Here is a telling example. Suppose you wish to trace the author and context of a quotation you have encountered, “Look thy last on all things lovely.” On my search, the first web page cited by Google attributes it to the poet Austin Dobson. This mistake is soon corrected: it comes from a Walter de la Mare poem, and all of the following references say so. The last stanza of this poem begins, “Look thy last on all things lovely / Every hour. Let no night seal thy sense in deathly slumber /

email, Google and Skype. All of one’s work, entertainment and communications can already be concentrated in one portable device. Although for good reasons many people still congregate in workplaces and educational centres, how long will this last? Travelling to one’s computer terminal in an office miles away, instead of working on it at home, will become comparatively rare as people are put off by transport difficulties and concerns over environmental impacts. One of the greatest promises of the internet relates to education. In times of teacher shortages, the benefits are obvious: one teacher online can instruct millions of

“To use the internet as an educational tool, its content must be audited for reliability”

Alternatively, I can use all eight of them to make the sides of an octagon, all of whose angles are the same, and all of whose vertices lie on a circle. What is the area of that octagon? £15 will be awarded to the sender of the first correct answer opened on Wednesday

18 February. The Editor’s decision is final. Please send entries to Enigma 1528, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@ newscientist.com (please include your postal address). The winner of Enigma 1522 is Richard Kennaway of Norwich, UK.

Till to delight thou have paid thy utmost blessing…” On another web page cited by Google this quotation is rendered as, “Look thy last on all things lovely. Every hour. Let no night. Seal thy sense in deathly slumber. Till to delight. Thou have paid thy utmost blessing…” There is a solecism in this last line: “thou have paid” should read “thou hast paid”. But the mistake was the poet’s, not the transcriber’s, and some of the web pages silently correct it – thus introducing an error about an error. Transcription mistakes abound on other web pages: “let not night” for “let no night”, “senses” for “sense”, and so on. These are minor matters here, but not if we were dealing with a mathematical or chemical formula. The lesson is that to make best use of the internet as an educational resource, its content has to be audited for reliability, and a system of classification introduced. Given that the internet is already the main resource for students, the need is urgent. I suggest that an international consortium of universities should set up panels to audit the worth of websites, endorsing those that are reliable. They should not censor, nor comment on matters of opinion – the price we pay for the internet’s open democracy is the rubbish it contains. But they should authoritatively identify worthwhile sites, and warn of factual error when it occurs. Without such expert monitoring, the internet will increasingly be a problem rather than a boon, and limited in educational value. ●

Enigma Ad hoctagon

No. 1528 Susan Denham I HAVE eight rods. I can use three of them to make the sides of a right-angled triangle of area 10 square centimetres. 44 | NewScientist | 17 January 2009

Answer to 1522 Real in the lead Twente beat Sporting; Sporting has a final total of 9 points and Twente has a total of 5 points Visit www.newscientist.com/topic/enigma for recent puzzles and worked solutions www.newscientist.com

PAUL MCDE

VITT

Feedback–

GRADE A gobbledegook is available for the reading pleasure of connoisseurs, thanks to the alertness of John Meyer, at www.ausangels.com/abfe_QandA. asp – home of Australian Bush Flower Essences. Curiously, the company is based in British Columbia, Canada. Presumably, exotic Australian things are doubly exotic there. We have space only for a small sample of the wondrousness: “When an Essence is ingested or absorbed through the skin, it is assimilated into the blood stream. Then it settles midway between the circulatory and nervous systems. There, an electromagnetic current is created by the polarity of the two systems. The Essence then moves directly to the meridians, which are vital mechanisms of interface between the subtle bodies and the physical body.” There are more revolutionary findings that should excite physiologists everywhere: “The quartzlike crystalline silica structures in the physical body, such as those in the bloodstream, the hair and nails, amplify and transmit the healing energies of the Flower Essences to their appropriate sights [sic]…” And at that, Feedback’s heart turned to stone. We did go back to discover that the Essences are prepared “by imprinting

On a reader’s tube of Colgate toothpaste it is written: “Clinically proven everyday protection against time.” So if you smear it on your head it will stop hair loss? 76 | NewScientist | 17 January 2008

a flower’s unique vibrational healing signature onto a carrier solution of brandy”. So they may be effective against sobriety, we’ll grant. “Perhaps,” John muses, “I need to take some Bauhinia, which is for ‘embracing new concepts and ideas. There may be some hesitation or reluctance, initially, in coming to terms with these’.” Feedback plans to douse an expenses claim – for a $385 correspondence course on flower essences – in this belief-inducing substance. Shhh, don’t tell the Editor. “ANY discussion of oral sex has clear links with the last two USA administrations,” write Marian Pitts and Anthony Smith in an editorial in the Australian journal Sexual Health (vol 5, p 315). It’s the sort of opening sentence that definitely grabs one’s attention. The reference to Bill Clinton was obvious, but what about George W. Bush? A curious Feedback read on, wondering if they had discovered Bush in one of those interesting moments that lead to sudden resignations “to spend more time with the family”. Alas, they only linked him to the issue of sexual abstinence, which he was in favour of, and through that to the discussion of “technical virgins” – those who, like Clinton, don’t consider oral sex to be intercourse. “The issues of what counts as sex and what one actually can do while remaining sexually abstinent are important questions,” the authors continue. They cite some fascinating statistics, such as a survey of 925 Californian teenagers aged 14 to 19, reporting that 44.2 per cent thought “genital touching was consistent with being abstinent”, 33.4 per cent considered oral sex OK, and 14.3 per cent thought anal sex fell within the boundaries of abstinence. They don’t mention if any of the Californians thought they could remain abstinent while having vaginal sex but, given the above, Feedback suspects some would have responded in the affirmative. The authors go on to cite a host of other surveys of other groups, but eventually the details and the sentences grow tortuously convoluted and academic. “Most oral sex,” they write, “is happening concurrently with vaginal or anal sex and so must be understood within the context of a more complex and multifactorial sexual encounter, yet these other activities seem somehow less worthy of consideration or our attention.” It makes Feedback recall a cynical response to the long-running

debate over sex education in schools – it would make sex seem so dull that pupils would lose all interest in it.

IS THIS the world’s most expensive chemistry book? Its description on Amazon is: “Chemical Shifts and Coupling Constants for Silicon-29 (Landolt-Bornstein: Numerical Data and Functional Relationships in Science and Technology – New Series) (Hardcover)” by R. R. Gupta, M. D. Lechner, H. Marsmann, B. Mikhova and F. Uhlig. It costs $8539 – a mere $18.44 for each of its 463 pages, as one Amazon customer-reviewer calculated. Another noted that while the 463-page tome “starts off a little slow, once you get into the third chapter, ‘Silicon Molecules: We Hardly Knew Ye’, you just can’t put this book down”. If you want a piece of this action but you’re feeling the pinch, don’t worry, Amazon has kindly made the shipping free. SPOTTED on the internal jobs bulletin board at the BBC by a reader whose anonymity we have carefully protected by losing their message for months: “Job title: Marketing Manager, Earth”. Marketing to whom? At www.earthsales.notlong.com you can see that the post is “no longer being advertised”. Has the planet been sold, then? Why were we not told?

FINALLY, our thanks to Dennis Kaye, who has sent us a photograph of two payment machines standing side by side in a car park in Redbridge, London, UK. Both have a notice on them saying: “Please use other machine.”

You can send stories to Feedback by email at [email protected]. Please include your home address. This week’s and past Feedbacks can be seen on our website. www.newscientist.com

The last word– CAN’T FACE IT Why do we grimace when we eat sour or bitter food?

● The body has stereotyped sequences of action for avoiding and responding to noxious stimuli such as pungency and acidity. Some resemble involuntary defences against physical attack and are similar through most of the animal kingdom, so they are almost certainly primitive in origin. In humans, a faceful of ammonia or acetic acid fumes causes retreat, closed eyes and arms thrown across the face, among other responses. A noxious mouthful of a salty, bitter, acidic or otherwise vile chemical that our species instinctively avoids, such as one’s own ordure, causes another range of reactions, related to spitting

“In humans, a faceful of ammonia or acetic acid fumes causes retreat, closed eyes and arms thrown across the face, among other responses”

survived and become entrenched is that such behaviour has evolved into a warning to offspring and associates: “Bad stuff! Beware!” These less vigorous communication signals evolved more recently than the primitive reactions, and accordingly vary more widely between species, but they serve the same functions: warning of danger or nastiness and indicating good feeding. Jon Richfield Somerset West, South Africa

BLACK HEADS After a while I find the shower heads in my bathrooms become clogged by black flecks of what is obviously some kind of organic material. A similar material accumulates in my coldwater taps if they have not been used for some time, but in this case it is in the form of a black ribbon. I recall from visits made to water-treatment plants in my student days that the passage of water through a filter leads to the build-up of a zoogloea – a translucent jelly-like layer of organic matter. But if something similar to this process is taking place in the shower, why is the material black and exactly what is it?

or vomiting. Typical responses include: drawing down the corners of the mouth or gagging in preparation to vomit; salivating to clear the mouth and dilute harmful substances; puckering to avoid more intake; closing the eyes for protection; and performing convulsions that would help free oneself from assault. More trivial stimulation – for instance, from piquant foods like pickles or mustard – provoke milder incipient reactions such as grimaces and shuddering. Perhaps the reason these different levels of reaction have

● I know this black jelly-like material well because it formed an integral part of my PhD studies, which were focused on the sort of water filters mentioned above. The material is a biofilm: a jelly made up of a layer of bacteria and their extracellular products. These commonly form at the interface between a solid and a flowing liquid. The black coloration comes from

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manganese, which is common in groundwater. When water emerges from a spring, any manganese it contains will be in the form of soluble ions. Part of the treatment process is to oxygenate the water with an air cascade, and in some areas chlorine is added to the water to oxidise both iron and manganese. The insoluble manganese oxides created in this process are filtered out before water enters the distribution system. An alternative to this chemical oxidation is to allow a biofilm of manganese-oxidising bacteria such as Leptothrix species to form within a sand filter as the water passes through the filter. This film can build up into a

“The ribbon-like nature of the slime shows that the biofilm has formed under conditions of fluid shear in which the film is stretched by the water flow” sheath that, in the case of Leptothrix discophora, can be up to 20 times the diameter of the bacterial cells. The ribbon-like nature of the slime shows that the biofilm has formed under conditions of fluid shear. In effect, the film is stretched out by the flow of water. These ribbons are known to biofilm researchers as “streamers”. Your questioner is seeing a biofilm of Leptothrix coloured black by manganese oxide. The water is safe to drink: manganese toxicity is not a problem in municipal water systems, but it can cause staining in laundry and plumbing. These biofilms are not at all dangerous, just messy. Chris Hope Lecturer in oral biology University of Liverpool, UK

FOOLED IN BLACKPOOL From the top of Blackpool Tower (approximately 150 metres) on the UK’s west coast, can you see the curvature of Earth along the Irish Sea horizon? I thought I could, but my friend disagreed. If I’m wrong, how high would we have needed to be? (Continued)

● Every time I read yet another theoretical contribution to your debate over whether the curvature of the Earth is apparent from the top of Blackpool Tower, I turn to the front cover of the magazine just to check that the word “scientist” is really still there. I would have thought that by now someone would have followed the scientific method: just do the experiment and report the result. I would certainly have had a look if I lived a little closer. John Twin Ross-on-Wye, Herefordshire, UK

THIS WEEK’S QUESTION Studying form When closely matched athletes are competing in events that involve running, swimming, throwing or lifting, why does one of them win one day and another the next? Surely whoever is the fastest or strongest will remain so, for a while at least. Often the original winner will return a few days later and win again, so why did he or she lose the race between the two victories? Magda Loncic Kiev, Ukraine

Do Polar Bears Get Lonely? A brand new collection – serious enquiry, brilliant insight and the hilariously unexpected Available from booksellers and at www.newscientist.com/polarbears

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