Zoologger: Fickle female guppies fancy fresh faces

Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world

Species: Poecilia reticulata

Habitat: The tropical fresh waters of northern South America and the southern Caribbean.

The excitement of the new. The attraction of the exotic. Sometimes it's nice to have a change.

This is a feeling female guppies know all too well. After being courted by one male, a female will shift her preference to males with markedly different appearances in as little as 7 minutes. Female guppies have no fixed type, it seems.

Male guppies come in a wide variety of coloured patterns – spots, streaks and irregular patches of a wide palette of colours, including black, orange, blue, green and violet. And it pays to stand out from the crowd: the rarer or more novel a male's colour patterns, the higher his chances of mating success.

To test whether female guppies really are attracted to something a bit different, Kimberly Hughes of Florida State University in Tallahassee and colleagues introduced single females to a group of four males, like the fishy equivalent of a cocktail party with too many male guests. Within these four, there were two types of body pattern, with two fish belonging to each type. While the two pattern types were very different from each other, the two fish that shared the similar pattern looked pretty alike.

Like an aquatic reality dating show, the researchers then peeked in on the action, as the males took turns to court the female. On the first day, females showed a clear preference for males that looked different to the previous male who had courted her, a change in taste that took about 7 minutes. The females were less interested in males who looked similar to the fish who had just attempted to chat her up.

Have we met before?

"There are a few hypotheses about why females would display such a preference," says Hughes. One explanation could be that females are trying to get as diverse a selection of genetic fathers for her offspring as possible, as judged by varied external markings. "It's possible for multiple males to fertilise a female's eggs," says Hughes. DNA testing has shown that a single brood of baby guppies can be sired by up to 12 different fathers.

Alternatively, the female might be trying to avoid inbreeding with a male relative by avoiding whatever looks familiar to her. "In the wild, if guppies do not move around much, females can end up living in the same pools with their brothers and sons," says Hughes. "If a male from upstream or downstream then disperses into the female's pool, he is likely to have an unfamiliar colour pattern, and he is also likely to be less related to the female than the males that are more familiar to her."

Or perhaps it's just a quirk of their fishy brains. It is possible that a female's ability to tell individuals apart might not be perfect, suggests Anne Houde of Lake Forest College in Illinois, who also worked on the study. She says a female may become tired of one male, and if the next male looks very similar, she might not realise he is a different fish.

A fleeting attraction

But the females' tastes for novelty did not last. On day two of the experiment, their behaviour changed once again. They showed no difference in attraction to similar and different males, perhaps because the four males had all become too familiar and their novelty had worn off.

"Our hypothesis is that after 24 hours, all the males had become familiar to the females," says Hughes. As a result, they would no longer seem novel and like a hot mating prospect.

The opposite might instead be true: after this time period, the females could better recognise and distinguish between the different males, making the immediate attraction of a fresh face less important. Houde compares this effect to teaching a class of new students, which at first are hard to tell apart except for a few distinctive individuals, but who become easier to recognise and distinguish between over time.

Journal reference: Ethology, DOI: 10.1111/eth.12313

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Beat temptation with the marshmallow psychologist

Today, we want everything now, yet you've just written a book about self-control. Why?

It's a widespread perception that the world is more and more one in which people are orientated to immediate gratification and don't know how to delay it. But when you look closely, I think that's probably not the case. If anything, there has been improvement in overall self-control. In fact, we're attempting to test that question in a study now.

What is really going on then?

There are a lot of reasons to think that many children growing up in the information technology revolution are developing the skills to delay gratification very well. That ability – psychologists call it executive control – shows whether they can keep a goal in mind, suppress impulses that interfere with reaching that goal, and use attention control abilities in the brain's prefrontal cortex to keep marching on until they reach that goal. ...

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How air conditioning overwhelmed its hothead haters

• Book information


• Cool: How air conditioning changed everything by Salvatore Basile


• Published by: Fordham University Press


• Price: $29.95

Without air-con we'd be packed in worse conditions than bananas (Image: Ashely Cooper/Aurora Photos)

It was a fight between vested interests and institutional boneheadedness, but as Cool: How air conditioning changed everything explains, common sense won out

"AN ATTACK dog of a tycoon" looms large in Salvatore Basile's charming history of a new technology and its struggles with vested interests. Frank Tudor, the Ice King, made a fortune in the 1830s cutting ice from New England rivers and lakes, only to be bested – eventually, and not without a fight – by a technology that promised to chill rooms using, of all things, steam power.

Needless to say, Cool is also about popular scepticism. "When it came to a contraption that could 'cool the air'," Basile writes, "not only did many people not understand why it was necessary, but plenty of them scoffed at the notion that such a thing could even exist."

Above all, Cool is about institutional boneheadedness. Basile's targets are predictable, but they only have themselves to blame. Just what were late 19th-century doctors thinking when they doled out advice on tolerating heat and cold?

Theatregoers, overheated by the crowds, found themselves struggling to breathe as hundreds of gas-jet lights gobbled up what little oxygen was left in the auditorium. Nonetheless, Basile recounts, "woolen and flannel undergarments were sternly recommended for the summertime, and the health profession advised perspiration-drenched people never to remedy the situation by removing any clothing since 'internal congestion of the abdominal organs and other evils' might result". According to US medical advice of the day, "the best way to endure heat is to drink as little as possible".

Much fun, too, is had at the expense of Washington's staffers and politicos, gasping for breath in grandiose, cast-iron, glass-roofed buildings in a city that was, according to legend, a hardship post for foreign diplomats because it was located "at the bottom of a topographical saucer where moist and motionless air settles with smothering compression".

Science and reason won out in the end, of course, even if the pioneering Carrier Air Conditioning Company of America was forced to market its machines as air "cleaners", rather than as air "coolers".

In the end, the sheer intensity of early 20th-century urban life made air-conditioning a necessity. The interiors of New York's skyscrapers, switchboard rooms and television studios could be literally blistering. Our sceptical and sweaty species was finally forced to accept that "a bunch of humans is entitled to treatment as good as that usually accorded a bunch of bananas", as the then Chicago Daily Tribune put it.

The technically minded reader might feel a little short-changed by Basile's short, sharp micro-history, but the essentials are all here: the problems of humidity, the risks posed by different refrigerants, and so on. And because 28 out of the 30 largest cities in the world today are in tropical climates, there will probably be a sequel soon.

This article appeared in print under the headline "The birth of the cool"

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Chimp social network shows how new ideas catch on

Three years ago, an adult chimpanzee called Nick dipped a piece of moss into a watering hole in Uganda's Budongo Forest. Watched by a female, Nambi, he lifted the moss to his mouth and squeezed the water out. Nambi copied him and, over the next six days, moss sponging began to spread through the community. A chimp trend was born.

Until that day in November 2011, chimps had only been seen to copy actions in controlled experiments, and social learning had never been directly observed in the wild.

To prove that Nambi and the seven other chimps who started using moss sponges didn't just come up with the idea independently, Catherine Hobaiter of the University of St Andrews, UK, and her colleagues used their own innovation: a statistical analysis of the community's social network. They were able to track how moss-sponging spread and calculated that once a chimp had seen another use a moss sponge, it was 15 times more likely to do so itself.

A decade ago it was believed that only humans have the capacity to imitate, says Frans de Waal of Emory University in Atlanta, Georgia. "The present study is the first on apes to show by means of networking analysis that habits travel along paths of close relationships," he says, adding that a similar idea was shown not long ago for humpback whale hunting techniques.

Caught in the act

Copying may seem like the easiest thing to us, but not all animals are able. Chimps at the Gombe Stream reserve in Tanzania can copy each other using twigs to fish out termites, but the baboons that watch them haven't picked up the trick. "They don't get it," says Andrew Whiten of the University of St Andrews.

Whiten previously listed 39 behaviours that were found only in some communities of chimps, suggesting these were picked up from other group members rather than being innate behaviours. Since then, more have been added, but they still number in the dozens, not the thousands.

Given how rarely chimps pick up trends, it's exciting that someone was on hand to watch it happen in this latest study, says Whiten.

Ultimately, he says, our ability to both invent and copy meant our ancestors could exploit a cognitive niche. "They began hunting large game by doing it the brainy way." Imitation, it turns out, is not just the sincerest form of flattery, it's also a smart thing to do.

Journal reference: PLoS Biology , DOI: 10.1371/journal.pbio.1001960

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Earth gets a new companion for trip around sun

Add one to the entourage. A newly discovered asteroid called 2014 OL339 is the latest quasi-satellite of Earth – a space rock that orbits the sun but is close enough to Earth to look like a companion.

The asteroid has been hanging out near Earth for about 775 years and it will move on about 165 years from now, say Carlos and Raul de la Fuente Marcos of Complutense University of Madrid in Spain, who have just described it.

Quasi-satellites orbit in resonance with Earth, allowing the planet's gravity to shift the rock's position much like an adult pushing a child on a swing, says Martin Connors, an astronomer at Athabasca University in Canada. The asteroid orbits the sun every 365 days, as Earth does, but Earth's gravity guides it into an eccentric wobble, which causes the rock to appear to circle backward around the planet.

Earth's retinue

The asteroid, which is between 90 and 200 metres in diameter, is among several different categories of space rock in Earth's retinue besides our one satellite, the moon. Rocks that hang out at a gravitational middle ground known as a Lagrange point, where they follow or lead Earth in its orbit, are called Trojans.

Mini-moons, meanwhile, are small asteroids that get sucked into Earth's gravitational pull and orbit the planet, but only for a few months or a year, says Paul Chodas at NASA's Near Earth Object Program. He spotted what appeared to be a mini-moon back in 2002, but it turned out to be the third rocket stage of the Apollo 12 lunar mission.

Most planets and even some large asteroids are accompanied by hangers-on. With four quasi-satellites catalogued so far, Earth comes in second only to Jupiter's six, though the gas giant probably has many more that we can't see. The same is probably true of Earth, as small space rocks are difficult to find – astronomers didn't spot the first till 2004.

"If you go into your kitchen and you see some big cockroaches, you know there are a lot of little ones there, too," Connors says.

Journal reference: http://ift.tt/1rISZma

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Blame climate change for heatwaves that struck in 2013

The verdict is in: climate change is guilty. Greenhouse gas emissions made five heatwaves in 2013 more likely.

That's the conclusion of the third annual assessment of the role of global warming in extreme weather events from the previous year. For 2013, the research included five separate heatwaves in Australia, China, Japan, Korea and western Europe. The report found that climate change played a part in all of them.

Australia's results were particularly damning. "The chances of observing such extreme temperatures in a world without climate change – it is almost impossible to imagine how that would have happened," says Peter Stott of the UK Met Office, an editor of the report, a special supplement in the Bulletin of the American Meteorological Society called Explaining Extreme Events of 2013 from a Climate Perspective .

But the Californian drought was too close to call. While heatwaves depend only on how hot the temperature is, heavy rains, floods and dry spells are more complex events, relying on mix of factors including atmospheric patterns, sea surface temperatures and rainfall. That makes it harder to tease out the role of climate change from natural variations in the climate. Studies of these types of events were less conclusive, and three studies of different factors in California's 2013-2014 drought found little or no role for global warming.

The extreme monsoon rains that hit India in June 2013, however, were found to have been made more likely by emissions.

The report has coincided with early data from the UK Met Office showing that this September was the driest for the UK on record – although we don't yet know if this is due to global warming.

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Rogue winds swept humans to last uninhabited islands

Shifting wind patterns could solve the mystery of how Polynesians colonised the most remote islands in the world

Earth's navel: Stare into an eye-wateringly big hole

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Rogue winds swept humans to last uninhabited islands

Expert navigation and advanced boat-building technology were not enough for humans to finally colonise the world's most remote islands – shifting wind patterns also played a part.

There were no humans on Easter Island in the south-eastern Pacific until the middle ages, when expert Polynesian sailors spread from the central Pacific islands. Within a few hundred years, they colonised previously uninhabited islands all across the South Pacific. But how they did so has remained a matter of some controversy.

Today winds blow from east to west in the tropics, and in the opposite direction further south. This would have made it an epic struggle against the wind to sail eastwards to Easter Island or westwards to New Zealand, and scientists have clashed over whether Polynesian seafaring could have coped with such a task.

The Polynesians would probably have needed fixed-mast canoes to sail against the wind, which there is no evidence of, says Ian Goodwin from Macquarie University in Sydney, Australia. Instead, his research suggests that these pioneering sailors might have had the winds in their favour after all.

"All previous research that's been done trying to understand this very rapid colonisation of the Pacific tried to grapple with the migration in terms of modern climate," says Goodwin, who teamed up with anthropologist Atholl Anderson from the Australian National University in Canberra.

They wanted to see whether wind patterns could help explain the migrations. Using evidence from tree rings, lake sediments and ice cores, they tried to reconstruct ancient climates. Their work showed that, for a couple of centuries, a unique set of wind changes would have made these journeys easier.

Catching the breeze

The wind record reveals that every few decades there were dramatic shifts in wind direction, corresponding to expansions and contractions of the predominantly warm, moist climates of the tropical regions, caused by warming of the western Pacific Ocean. Many of these events explain the movements of Polynesians' across the pacific.

From 1080 to 1100, the tropics contracted, moving the westerly winds further north. This would have created ideal sailing routes from the already colonised South Austral Islands to Easter Island – exactly when many archaeologists now think the island was colonised. Later, from 1140 to 1160, the opposite happened. The tropics expanded, and the easterly winds moved further south, allowing migration to New Zealand, which corresponds with archaeological and oral history records.

But the wind changes seem to have stopped as suddenly as they emerged – which could be why there don't appear to have been any major voyages after 1300

Debating blows on

Terry Hunt, an anthropologist at the University of Oregon in the US, believes the timings are significant. He and his colleagues previously established exactly when some of the colonisations happened using radiocarbon dating. "When we wrote our paper, we were saying to ourselves 'something must have erased distance in the rapid colonization of the remote Pacific.' These windows may be the critical clue," he says.

Dilys Johns from the University of Auckland, New Zealand, is more reserved about the role the wind played for the Polynesians' rapid spread across the South Pacific. "It's good to know they had chunks of time when it wouldn't have been as difficult," she says, but she still believes Polynesians were probably capable of sailing against the winds.

Hunt disagrees. "I think this is a compelling argument that an upwind capability was not necessary for long-distance voyaging, and indeed did not play a role."

Journal Reference: PNAS, DOI: 10.1073/pnas.1408918111

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Earth's navel: Stare into an eye-wateringly big hole

(Image: Slava Stepanov/gelio.livejournal.com)

THE eastern Siberian mining town of Mirny is home to the second-largest excavated hole in the world. The Mir diamond mine operated for 54 years, producing over 10 million carats (2 tonnes) of diamonds per year at its operational peak in the 1960s.

It was established in 1957, after geologists discovered traces of kimberlite, a rock known to sometimes contain diamonds. Once excavation was under way, the town of Mirny sprang up. Now closed, the Mir mine once employed 3600 people. Today the town's 37,000 inhabitants go about their lives next to a hole 525 metres deep and 1.2 kilometres wide. (The world's biggest excavated hole is the Bingham Canyon copper mine, Utah, which is 1 km deep and 4 km wide.)

The pit has been dubbed "the navel of the Earth". The air space above it is now closed, after unverified reports that helicopters had been pulled towards the mine. It is thought this could occur because the pit is so large that its shape and differences in surface temperature may create unusual airflow. For an idea of the sheer size of the pit, see the zoomed-in section, below.

The mine's largest diamond was found in 1980. It weighed 342.5 carats (68.5 grams) and was named in honour of the forthcoming congress of the Communist Party of the Soviet Union. The diamond's name? 26th Congress of the CPSU. Catchy.

This article appeared in print under the headline "Navel of the Earth"

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Behind the smile: What dolphins really think

Beguiled by a smile? (Image: Flip Nicklin/Minden Pictures)

They have been hailed as the second most intelligent animal on the planet, but could a soft spot for dolphins have led us to terribly misjudge them?

EVERY day, regular as clockwork, the bottlenose dolphins of Shark Bay swim to the shallows to be hand fed and beamed at by a gaggle of tourists. Meeting them was to be the highlight of my trip around Australia. I was expecting to commune with nature. Instead, I got a rude awakening. As dolphin after dolphin swam past my legs, excitement overcame me and – against the orders of the ranger on duty – I chanced a stroke. In response, I got a flick of the tail so hard it gave me a dead arm. I looked at the dolphin. Black eyes glared back at me. "She's telling you 'no'," said the ranger ...

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How to be genuinely yourself when always online

• Book information


• The End of Absence: Reclaiming what we've lost in a world of constant connection by Michael Harris


• Published by: HarperCollins


• Price: $26.95

• Book information


• The Glass Cage: Automation and us by Nicholas Carr


• Published by: W. W. Norton


• Price: $26.95

Don't lose yourself in a digital world (Image: Patrick Zachmann/Magnum Photos)

If you want to be free in a digital age, must you switch off your computer, ask two new books, The End of Absence and The Glass Cage

WHAT is it like to be alive at the moment? How is our sense of self changed by what we experience? Can we even say there is such a thing as an indelible self of the kind envisioned by psychoanalyst Carl Jung? And, if so, what impact does technology have on it?

The End of Absence by Michael Harris and The Glass Cage by Nicholas Carr grapple with these fundamental, intriguing questions. Harris discusses "what we've lost in a world of constant connection", while Carr muses on how automation influences us. Both authors are concerned with the cyber revolution and how it has affected society and the self.

Harris, in his mid-thirties, feels that he is one of the "translators of Before and After". He points out that, before long, no one will remember a time before the internet, and asks what this unavoidable fact means.

At the beginning of his story, Harris is a full-time journalist. He spends his days emailing, tweeting, watching videos of dancing cats, uploading pictures of his lunch and so on. One day, Harris realises he has an excessive number of windows open on his computer at the same time, and a text appears on his phone from an ignored friend: "Dude, are you alive or what?"

He fears he may be making an unnerving realisation: the internet has become the "real world" and physical reality is being set aside. "The daydreaming silences in our lives are filled; the burning solitudes are extinguished," he says. Longing for his lost solitude, Harris quits his job and embarks on a quest to regain the "absence" of before.

For a while Harris boycotts the internet altogether, discerning that "if solitude feels painful, it's only because we don't know how to be alone" – words inspired by American polymath Henry David Thoreau. Harris is eloquent on virtual narcissism, the "inauthenticity" of augmented reality, filter bubbles and web curation. He spends evenings at home, reading War and Peace, in the hope that Tolstoy might offer an antidote to cyber-surfeit. I suspect Tolstoy would have been tweeting himself senseless were he alive today. But Harris is sick of the internet, just genuinely bored.

Carr's The Glass Cage is also about how the digital age is changing who we are. Automation makes lives easier and chores less burdensome, but it also has "deeper, hidden effects... Automation can take a toll on our work, our talents, and our lives. It can narrow our perspectives and limit our choices."

Here, too, the main concern is our loss of alertness and individuality. The complacency automation breeds can lead to collective stupor: drivers blindly follow their satnavs even to the brink of a fast-flowing river or gaping abyss. Pilots, used to relying on autopilot, forget how to fly.

Concerning the promise one Google executive made that Google Maps would mean "no human ever has to feel lost again", Carr remarks: "To never confront the possibility of getting lost is to live in a state of perpetual dislocation." Silicon Valley's obsession with streamlining people's lives using software reduces the individual to "a passenger in his own body".

Carr's vision is bleak – and exaggerated, as is Harris's description of a life of cyber sound and fury, signifying nothing. Yet both authors emphasise that they don't want to return to the predigital age. Carr makes a crucial point when he argues that the real sentimental fallacy today is "the assumption that the new thing is always better suited to our purposes and intentions than the old thing. That's the view of a child, naive and pliable." And neophilia fuels consumerism: if people believe new equals good, they are more likely to chuck out last year's iPhone and queue overnight for the latest model.

So technology is only an aspect of a bigger problem: the way extreme capitalism stymies the individual. Take Facebook founder Mark Zuckerberg's notorious proposal that people today can only have one identity, and even that acting differently with friends and co-workers shows "a lack of integrity". We are, Carr says, "creatures of the Earth. We're not abstract dots proceeding along thin blue lines on computer screens." When the drivers of the internet convert us into market algorithms, or objects of surveillance, our unease is as much about inequality as about the technology itself.

Both Harris and Carr seek to disentangle the individual from the ties that bind, and to detach the "I" from the "we". The advice? Do (almost) anything, so long as it is genuinely felt – intended, rather than imposed. Do not sleepwalk across the internet, or elsewhere. If you want Google Glass attached to your face, go ahead.

On the other hand, beyond the dire compulsion of earning a wage, no one has a gun to your head: "Tweet or die!" We can exist passionately and distinctly, online or offline. We can develop complex, authentic experiences beyond the grasp of the most sublime algorithm, so long as we are truly and freely ourselves.

This article appeared in print under the headline "High-tech psyche"

Joanna Kavenna is a novelist and journalist

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Japan eruption practically undetectable in advance

(Image: Reuters/Kyodo)

Rescue workers are the only dots of colour in the ashen landscape at the peak of Mount Ontake in Japan, after the volcano erupted without warning on Saturday.

Hikers and volcano-watchers were smothered by fine ash and other debris that swept down the mountainside without warning. Up to 36 people may have died and the emergency services report that there are still people missing.

The Japan Meteorological Agency (JMA) has raised the warning level for Ontake to level 3 of 5, urging people not to approach the volcano. Level 5 means people in surrounding areas should evacuate.

The agency said that Saturday's event was a phreatic explosion, when magma rapidly heats water into steam, causing it to explode out of the volcano. This created a pyroclastic flow of ash and rock.

A head of steam

The event has sparked calls for a reliable early warning system for volcanic eruptions. However, volcanologists contacted by New Scientist say that this type of eruption is practically undetectable in advance using current monitoring technology, and could occur at many apparently sleeping volcanoes.

Monitoring is normally restricted to detecting unusual seismic activity, noticing obvious bulges and deformations in the volcano, or detecting the upwards movement of magma inside. None of these would have picked up the build-up of steam within pre-existing magma that happened in this case, says Dougal Jerram, founder of volcano blog DougalEarth.

"If the rocks are viscous and rich in silica, the de-gassing causes violent tearing apart of the material which causes formation of these fine ashes," he says. "Whenever you walk around any volcano that's dormant or poorly active, there's always the risk of these explosive eruptions."

"Because there's no new magma injection or tilt movement of the volcano, these eruptions are highly unpredictable," says geophysicist Ian Stimpson of the University of Keele, UK.

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Chagos marine reserve polluted by politics

Continue reading page |1|2

Exiled Chagossian islanders complain that a marine reserve gives fish more rights than them. They have a point

ADVICE to the UK's foreign secretary David Miliband was clear. For 48 hours, memos flew from his officials, all advising him to hold back, take his time, consult and consider alternatives.

He ignored them. The next day, five weeks before the 2010 election that would remove him from office, Miliband set up a giant marine protected area (MPA) covering 640,000 square kilometres of the British Indian Ocean Territory (BIOT), an area roughly the size of France. It meant a ban on fishing around the tiny islands of the Chagos archipelago, a leftover from the British Empire. Only Diego Garcia, an atoll with a massive US military base, was excepted.

While the MPA suited the US, it angered former Chagossians, who 40 years before had been shipped to Mauritius and Seychelles to make way for the US. They say the ban is meant to stymie demands to return to some islands and set up fishing businesses. They could be right. Certainly, it lacks scientific credibility and diplomatic integrity.

Miliband's rushed decision was always curious. And now the plot thickens. Official memos released to a judicial review of the MPA to appear in Advances in Marine Biology, vol 69, in a paper by Richard Dunne, British barrister and coral reef scientist, show that Miliband snubbed his civil servants and fisheries advisors, who said the scientific case for the MPA did not stack up.

Miliband is not saying why. He did not respond to requests for a comment. Was it crude geopolitics – a "blue grab" of strategically valuable ocean? Or was it environmental zeal from a man who later became co-chair of the Global Ocean Commission?

The memos suggest a potent but confused mix of both.

The MPA idea came from the Pew Environment Group, a US-based non-profit organisation. Miliband adopted it in May 2009, becoming "really fired up", as one official memo put it. He held a quick public consultation, during which one of the 5000 exiled Chagossians complained: "The fish will have more rights than us." On 30 March 2010, he said he wanted to go ahead before the general election on 6 May. His officials, the memos reveal, were horrified – especially by the haste.

"This approach risks deciding (and being seen to decide) policy on the hoof for political timetabling reasons rather than on the basis of expert advice and public consultation," wrote Andrew Allen, head of Southern Oceans at the Foreign Office. Joanne Yeadon, head of the BIOT section, feared a legal challenge, where the government would need to show "a conscientious and careful decision-making process. A rapid decision now would undermine that."

When Miliband established the MPA on 1 April, perhaps he was consciously aping George W. Bush. In virtually his last act as US president in 2009, Bush set up a giant MPA in the Pacific, despite warnings that it extended beyond US territorial waters and was opposed by island leaders.

At any rate, Miliband was joining a trend for combining conservation with geopolitics. Ten mega-MPAs have been established in the past decade. But the conservation case is sketchy, says Pierre Leenhardt of the University of Perpignan, France. He argued that "we still lack scientific studies showing their benefit or effectiveness", while in most cases they conflict with the rights of indigenous communities.

And so with Chagos, where Miliband's officials considered the MPA bad science, bad economics, politically duplicitous and, most surprisingly, bad for the environment. Miliband argued that banning fishing was vital to protect ecosystems. But, as Dunne shows in his paper, much advice said otherwise. For one thing, fishing was minimal. The territory's fisheries consultant, the Marine Resources Assessment Group, said the ban "will provide no conservation benefit for tuna", the main fish stock. That advice should have been heard at the heart of government, as MRAG founder John Beddington was then chief scientific adviser.

What an MPA would do was undermine resettlement plans. We know from US Embassy messages unearthed by Wikileaks that Miliband's officials told the Americans that "establishing a marine park would, in effect, put paid to resettlement claims". Now we know that is the case.

"Creating a reserve," the director of overseas territories Colin Roberts wrote in a memo in May 2009, "could create a context for a raft of measures designed to weaken the [resettlement] movement." Top of his list were "presenting new evidence about the precariousness of any settlement" amid a fishing ban, and "activating the environmental lobby", which he thought would out-campaign the Chagossians.

Most conservationists predictably backed the MPA. But David Snoxell, a former British high commissioner to Mauritius, says they were pawns in a game. And what did the greens get? The truth is that the civil servants believed all along that the marine environment could be worse off.

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Why we weren't ready for Ebola

Peter Piot co-discovered the deadly virus nearly 40 years ago, but says it wasn't thought a major public health threat – until now

You discovered the Ebola virus in 1976. How?

My lab received a blood sample from a Belgian nun who had died in Zaire (now the Democratic Republic of the Congo). She was diagnosed with yellow fever, but when we isolated the virus, it didn't look like anything we knew. Under the electron microscope it looked like a worm.

Then we got news from the World Health Organization of a major epidemic with a very high mortality rate in Zaire. We were told to stop all investigations because our lab wasn't equipped to deal with dangerous viruses. So we sent the virus to the US Centers for Disease Control in Atlanta. They confirmed that it was a new virus.

What happened next?

The next step was to figure out how the virus was transmitted and to stop the epidemic. So I went with a team to the epidemic zone in the equatorial forest in the northern part of Zaire. It was my first time ever in Africa, and I was just 27 so I had zero experience. But we did the detective work, unravelling how this virus was spreading.

Nearly 40 years after the virus was found, are you surprised at how bad the situation is?

Yes. This Ebola epidemic has killed more people than all the other epidemics together. It is a perfect storm: a virus hiding in the forest, likely in bats; people who are more exposed to the forest due to deforestation and other factors; no trust in authorities after decades of civil war and a corrupt regime; and a dysfunctional health system. You also have strong beliefs about disease causation, traditional funeral rites that require the family to touch the body and mistrust in Western medicine. Finally, there is the very slow response – both nationally and by the international community.

How was the international response lacking?

We were all far too late. Even today with the much enhanced support, we are still running behind the virus. The epidemic is expanding. Every week the number of deaths is greater than the week before.

Experimental treatments are now being tested. Why hasn't this happened sooner?

After the 2001 anthrax scare, an anti-bioterrorism programme largely funded by the US Department of Defense led to the development of a few vaccines and experimental drugs for Ebola. But the funding dried up. Until now, Ebola hasn't been a real public health issue compared with HIV, malaria, maternal mortality and so on. But now we must accelerate evaluation of experimental vaccines and offer some of the drugs for palliative use.

What are the most promising treatments?

We still need to go through human trials for a potential vaccine, but that will take months and might well be too late for this epidemic.

For treatment, we can use blood plasma or serum from people who have recovered from Ebola – when you recover from an infectious disease you have very high levels of antibodies in your blood. But let's make sure treatments are well evaluated. For the next epidemic we need to have stockpiles of vaccine and drugs that can be mobilised immediately.

This article appeared in print under the headline "Outpaced by Ebola"

Profile

Peter Piot is a professor of global health and director of the London School of Hygiene and Tropical Medicine. In 1976 he co-discovered the Ebola virus while working at the Institute of Tropical Medicine in Antwerp, Belgium

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Cosmic ray blitz: Space invaders that fry electronics

Cosmic rays threaten electronic chaos (Image: Valero Doval)

Intergalactic visitors threaten to bring chaos to our electronic world. Is there anything we can do?

THE travellers hurtle towards Earth at close to the speed of light. Their origin is uncertain: some may have been born in mammoth supernovae far across the universe, travelling for millennia before reaching us. Yet in the time it has taken you to read this, billions of them have smashed into our planet's atmosphere, raining down sub-atomic shrapnel that is passing right through you. These travellers are cosmic rays, a source of intrigue for astronomers, particle physicists, space scientists... and the car industry.

Car manufacturers are just the latest group to appreciate the importance of these mysterious particles. For decades physicists have known that high-energy cosmic rays and the particles they generate can contain enough energy to damage sensitive electronics. Yet we are packing ...

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India's Mars triumph signals a rising space power

"There is nothing symbolic about this," says Sundaram Ramakrishnan of the Indian Space Research Organisation. The country's success in putting its Mars Orbiter Mission(MOM) into orbit around the Red Planet was about testing technology and the skills needed to manage a complex mission, he says.

ISRO scientists passed that test with flying colours during the early hours of 24 September. When word came in that the craft had executed its burn for precisely 1388.67 seconds and slowed to enter orbit, staff were ecstatic.

"There was euphoria among people, hugging each other, shaking hands, and jumping," Anil Bhardwaj, director of the space physics laboratory at ISRO's Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram, Kerala, told New Scientist. "I can't tell you in words the way we were feeling."

Beyond the celebrations, and the celebratory headlines – "The first Asian country to reach Mars", "India's Mars mission cost less than the making of the movie Gravity" – is a space programme that is quietly gaining in confidence and competence to tackle lunar and interplanetary missions.

Making of a Mars shot

Getting to Mars on the first try was no mean feat, showing that ISRO is able to tackle a range of highly technical challenges in a coordinated way. These included modelling the precise trajectory to Mars, designing an intelligent craft that deals with problems autonomously when too far from Earth for real-time control, and building engines robust enough to function flawlessly after a year in the cold of space. "It definitely gives us confidence to plan such complex missions," says Ramakrishnan.

And Mars was achieved at a low cost too: $74 million, indeed less than what it took to film Gravity , by some $26 million. Bhardwaj credits tight cost-control, founded on ISRO's ability to do everything in-house – including building rockets, satellites, propulsion systems and sensors. ISRO does sub-contract some manufacturing to industry, but manages the entire process itself. This, says Bhardwaj, also helps the organisation keep to tight deadlines: from conception to rendezvous with the Mars, the mission took three years.

More in the pipeline

With one triumph under its belt, ISRO is not resting on its laurels. Having put the Chandrayaan-1 probe in orbit around the moon in 2008, the agency has India's next lunar mission in the works, this time involving an orbiter, lander and rover. "This is another new technology that we'll need for landing on any planetary surface," says Bhardwaj.

The rocket for this second moon mission will be the heavy-lift Geosynchronous Launch Vehicle (GSLV). It successfully flew earlier this year with a cryogenic engine that uses liquid oxygen and hydrogen for fuel – a vital technology for large payload missions – designed and built in India.

Another key mission in the pipeline is Aditya-1 (Aditya being the Hindu sun god). It will attempt to study the sun from Lagrangian point L1, which lies between Earth and the sun, about four times as far away as the moon.

In the meantime, ISRO is also building its own GPS system. It has already launched two satellites, with a third awaiting launch. The next generation of weather, remote sensing and communication satellites are also on the agenda.

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Today on New Scientist

Kew's Intoxication season: live the high life

From blue lotus to kola nut, just what does it take to get off your face in London's Kew Gardens?

Feedback: Bigger and bigger beasts

Great towering measurements, helping number the number helpers, now they know how many holes it takes… and more

Four ways you can see the multiverse

The multiverse, where every choice spawns many universes, sounds like a philosopher's fantasy, but these four experiments show it may be very real

Spacecraft duo beam back their first Mars snaps

In their first images, India's orbiter tweets a top-down view of the Red Planet while NASA's spacecraft shows four faces of Mars

Tumour traps: How to arrest cancer as it spreads

Some surgery to treat cancer can actually make it spread. But traps to mop up tumour cells as they infiltrate the body can boost chances of survival

Hotspots in India's tiger-trading network revealed

The traders in tiger parts prefer to smuggle their illegal wares via the nation's railway routes, reveals data on 40 years of poaching

Up to half of Earth's water is older than the sun

Modelling suggests much of the solar system's water comes from interstellar space, meaning many exoplanets could well have water too

Make tough tasks seem easier by zapping the brain

Can you trick yourself into feeling stronger? Yes, if you stimulate the brain in the right away

Ageing societies will be better for the planet

As lifespans rise and fertility rates fall, the ageing of Western industrial societies could help reduce carbon emissions

Cosmic inflation is dead, long live cosmic inflation!

The BICEP2 results hailed as demonstrating inflation in the early universe now seem to do the exact opposite, if they can be trusted at all

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Kew's Intoxication season: live the high life

Grandmaster Sam gets Kew's Intoxication season going (Images: David Stock)

From blue lotus to kola nut, just what does it take to get off your face in London's Kew Gardens?

Here's something you don't see often: disclaimers being handed out to the first-night visitors before they even receive a drink.

But then, it is no ordinary event and the organisers aren't taking any chances. The Plant Connoisseurs' Club, part of the Intoxication Season at London's Royal Botanic Gardens in Kew, is where you can get legally high. "Don't worry," says our host, Grandmaster Sam. "There has been some very intense health and safety."

Just as well. We were off on a journey into the strange world of intoxicating plants: flora ingested by humans for millennia for their stimulating, mood-enhancing or hallucinatory effects.

While this may conjure images of shamen drinking an ayahuasca brew, partygoers snorting lines of cocaine or rolling joints, it's not that simple. "Look around Western culture today and we are beset with legal stimulants and depressants at every turn," says Sam Bompas, one half of Plant Connoisseurs' Club organisers Bompas and Parr.

Quite right. How many coffees have you had today? Cups of tea? A beer, maybe? Or a cigarette? All good, legally sanctioned and taxable highs.

While Grandmaster Sam regales us with tales of far-flung cultures, strange hallucinatory experiences and ritualistic bonding over shared gourds of kava, Sam Bompas supplies the goodies to spice up our lives.

There's areca nut (picutred below), a peppery, barky stimulant derived from the areca palm (Areca catechu) and betel leaf (Piper betle) enjoyed by millions across Asia. Kola (Cola), a tropical African nut, is a source of caffeine in many soft drinks.

Before we decide on our menu of legal highs, our host brings trays of freshly prepared blue lotus tea. The pretty blue flowers of this relative of the lily (Nymphaea caerulea, see picture above) are smoked or brewed to produce a mildly sedative and psychoactive effect. After getting a whiff of its flowery, potpourri smell I wasn't expecting the earthy, slightly bitter, vegetable-like taste. Still, we compared notes and excitedly awaited the outcome.

The club is just one part of Kew's Intoxication season. As you'd expect from the world-renowned botanic garden, there is an "intoxicating" display of plants and fungi too. Tea, coffee, tobacco and tequila's blue agave (Agave azul) sit next to more unusual forms of potent plant life – salvia (Salvia divinorum), kava (Piper methysticum), peyote (Lophophora williamsii) and khat (Catha edulis) not to mention the toxic and famously delirium-inducing Datura plants.

The cannabis and khat plants are safely stored behind lock and key, and coca, the raw material for cocaine, is notable by its absence. Despite Kew's best attempts, coca was "too difficult to clear Home Office regulations", according to Monique Simmonds, head of the sustainable uses of plants group.

Yet, as she points out, plants aren't inherently good or bad, and their complex compounds and uses are scientifically interesting. Heroin is socially unacceptable, yet it derives from the opium poppy and chemically is just a tiny step away from codeine, morphine and other common opioid painkillers.

Clearly, then, there is a fine line between drugs for medicine and drugs for recreation – with some plants providing both.

And some have myriad uses, like cannabis (which also needs a special Home Office licence). One variety, hemp, is well known for its potential in paper, textiles, paint and plastics manufacturing. Recently researchers suggested hemp could even usurp graphene as the future material for super-capacitors, providing a low-cost, renewable raw material for energy storage. And in medicine, too, cannabis is a star, helping with everything from easing chemotherapy side effects and chronic pain to the treatment of post-traumatic stress disorder.

Cannabis contains nearly 500 chemical compounds, 85 of which are unique to the plant, so there is a lot still to learn. Yet legal barriers can make legitimate scientific study difficult.

It wasn't that long ago that Coca-Cola contained actual cocaine, and opium dens were widespread in the 19th century. Georgian London's gin habit would put today's binge drinkers to shame, while Prohibition in the US had very mixed results. As Simmonds says: "If we looked back 50 to 100 years, it would be a different set of plants on display - coca, cannabis and opium might be the accepted ones."

Back in the Connoisseurs' Club, I was still waiting for the blue lotus hallucinations to kick in. But all I got was a mildly calming feeling, and it was hard to attribute this to anything beyond anticipation.

Moving on, it was time for cocktails at the Botanical Bar.

Nutmeg-infused rum, quince syrup and ginger ale, anyone? Nutmeg, it turns out, contains the psychoactive drug myristicin. Would this get me high? On second thoughts, no – it would take about two large tablespoons of nutmeg for any effect and, once the nausea, vomiting and diarrhoea subside, a delirious, paranoia-inducing trip takes over, lasting up to 48 hours with one hell of a hangover to follow.

Happily, with the sun setting over the secret lawn at Kew, the rum took hold. Success at last! I'm relaxed, chatty, inebriated and carefree.

It was a trip, of sorts, one straddling a controversial line, as Kew's director of public programmes, Gay Coley, acknowledged: "We are unashamedly using controversy to spark debate."

And with a whole season of events, with enticing titles like "Cannabis: pleasure, madness …and medicine?", "Did Coffee make modern politics?" and "Psilocybin, telepathy and religious experience" I suspect there is plenty more controversy to come.

Intoxication season Royal Botanic Gardens, Kew, London, until 12 October

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Four ways you can see the multiverse

Every time you make a choice, you spawn a multitude of universes, leading to umpteen other yous – some of them living very different lives. This raises a myriad of moral conundrums, from what we owe our other selves to the death of hope.

Read more: "Multiverse me: Should I care about my other selves?"

It sounds like a concept from a philosopher's fevered imagination, but many physicists believe the multiverse is real. And they've got evidence – here are four here are four ways that multiverse may show itself in our everyday world.

1 The wave function

This mathematical entity describes the properties of any quantum system. Such properties –– an atom's direction of spin, say –– can take several values at once, in what is known as quantum superposition. But when we measure such a property we only get a single value: – in the case of spin, it is either up or down.

In the traditional Copenhagen interpretation of quantum mechanics, the wave function is said to "collapse" when the measurement is taken, but it isn't clear how this happens. (Schrödinger's famous cat, neither alive nor dead until someone looks inside its box, illustrates this.) In the multiverse, the wave function never collapses: rather, it describes the property across multiple universes. In this universe, the atom's spin is up; in another universe, it's down.

2 Wave-particle duality

In the landmark experiment, photons are were sent one at a time towards a pair of slits, with a phosphorescent screen behind them. Take a measurement at either slit, and you'll register individual photons passing particle-like through one or the other. But leave the apparatus alone, and an interference pattern will build up on the screen, as if each photon had passed through both slits simultaneously and diffracted at each, like a classical wave.

This dual character has been described as the "central mystery" of quantum mechanics. In the Copenhagen interpretation, it is down to wave function collapse. Left to its own devices, each photon would pass through both slits simultaneously: the measurement at the slit forces it to "choose". One way to explain the interference pattern through many worlds, by contrast, is that each photon only ever goes through only one slit. – Tthe pattern comes about when a photon interacts with its clone passing through the other slit in a parallel universe.

3 Quantum computing

Though quantum computers are in their infancy, they are in theory incredibly powerful, capable of solving complex problems far faster than any ordinary computer. In the Copenhagen interpretation, this is because the computer is working with entangled "qubits" which can take many more states than the binary states available to the "bits" used by classical computers. In the multiverse interpretation, it's because it conducts the necessary calculations in many universes at once.

4 Quantum Russian roulette

This amounts to playing the role of Schrödinger's cat. You'll need a gun whose firing is controlled by a quantum property, such as an atom's spin, which has two possible states when measured. If the Copenhagen interpretation is right, you have the familiar 50-50 odds of survival. The more times you "play", the less likely you are to survive.

If the multiverse is real, on the other hand, there always will be a universe in which "you" are alive, no matter how long you play. What's more, you might always end up in it, thanks to the exalted status of the "observer" in quantum mechanics. You would just hear a series of clicks as the gun failed to fire every time – and realise you're immortal. But be warned: even if you can get hold of a quantum gun, physicists have long argued about how this most decisive of experiments would actually work out.

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Spacecraft duo beam back their first Mars snaps

The first snapshots from two orbiters currently dancing a waltz around Mars reveal completely different perspectives on the Red Planet. Today, India's MOM (Mars Orbiter Mission) spacecraft – also called Mangalyaan, meaning Mars Craft – tweeted its first image of the surface of Mars (see below) with the message "the view is nice up here".

(Image: ISRO)

Meanwhile, NASA's MAVEN spacecraft sent back four views of Mars: three images taken in different wavelengths of ultraviolet and a fourth picture, made from combining the others.

The blue version shows ultraviolet light from the sun scattered by hydrogen gas, stretching thousands of kilometres above the planet's surface. In the green image, sunlight is primarily reflected off oxygen, covering a smaller area than the cloud of hydrogen. The red picture shows ultraviolet sunlight reflected from the planet's surface, revealing a bright spot in the lower right that is due to either polar ice or clouds.

(Image: Laboratory for Atmospheric and Space Physics, University of Colorado; NASA)

MOM and MAVEN's success in reaching the Red Planet means we now have seven robonauts exploring Mars. Odyssey, Express and the Mars Reconnaissance Orbiter are observing the planet from orbit while Curiosity and Opportunity are on the ground roving its surface.

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Tumour traps: How to arrest cancer as it spreads

Traps and lures could stop cancer from spreading (Image: Jimmy Turrell)

Some surgery to treat cancer can actually make it spread. But traps to mop up tumour cells as they infiltrate the body can boost chances of survival

IT IS the medical symptom that many of us fear the most: a lump. If it turns out to be cancer, we face, at best, a painful and debilitating course of treatment, and at worst, well... the worst.

And yet, paradoxically, this lump is not what kills most people. As long as it is somewhere accessible, a single, discrete tumour can usually be cut out.

It is only once cells escape from this primary tumour and settle elsewhere in the body – like the brain, liver, lungs or bones – that cancer typically becomes deadly. At this stage, there may be so many secondary tumours that repeated surgery becomes a ...

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Hotspots in India's tiger-trading network revealed

Poaching gangs are using India's train networks to smuggle tiger parts across the country undetected. That's according to research that has mapped the hubs of illegal tiger poaching and trafficking activities.

Researchers analysed 40 years' worth of tiger trade data, collected by the Wildlife Protection Society of India (WPSI), and found that today's trafficking hotspots form a corridor running from southern and central India right up to the country's border with Nepal. This porous border is thought to be the main international hub for trafficking tiger parts into China.

The illegal trade in tiger parts continues to flourish in India, driven by the high demand for tiger parts elsewhere in Asia. The study identified 73 districts in India which may be active hubs for tiger poaching and illegal trafficking. These hubs were not limited to areas near tiger habitats: 17 districts were active but distant hubs, including the Delhi region.

Trafficking was higher in districts closer to railway routes than highways. "Poaching gangs and middlemen prefer to use trains to transport tiger parts, since trains are well-connected to remote forested areas and usually crowded," says Belinda Wright from WPSI. "Buses, in comparison, carry fewer people and can be easily stopped and checked."

Detection-avoidance

In 2012, WPSI recorded 32 cases of poaching and trafficking of wild-tiger parts, rising to 42 in 2013. But an increasing number does not necessarily mean that actual tiger trafficking has gone up, stresses the study's lead author, Koustubh Sharma of the Nature Conservation Foundation in Mysore, India. The number of reported cases depends on how many are detected, which can fluctuate according to levels of law enforcement. Over the 40-year study period, the number of cases decreased in some years, but this might be because poachers and buyers were using newer techniques to avoid detection.

Poaching is insidious, says Wright. "It can wipe out entire populations of tigers before the management even knows that such a threat exists in the area." This happened to the Sariska Tiger Reserve in north-west India in 2004.

The researchers hope that their findings will help enforcement agencies crack down on poaching and monitor their enforcement strategies.

According to Ullas Karanth, director of the Centre for Wildlife Studies in Bangalore, protecting tigers will require improved preventative patrols, rather than only chasing traders after they have killed a tiger.

He adds that, for India's tigers, depletion of prey in tiger habitats could be an even bigger threat to the species.

Journal reference: Biological Conservation, DOI: 10.1016/j.biocon.2014.08.016

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Up to half of Earth's water is older than the sun

Who would have guessed that Earth's oceans are older than the sun? Much of the water on our planet and around the solar system started out as tiny grains of ice floating in interstellar space. The discovery provides important clues about not only the make-up of our solar system, but also what planets around other stars might be like.

"Water is an essential ingredient that pretty much all known forms of life on Earth need to flourish," says Ilsedore Cleeves at the University of Michigan in Ann Arbor. "To understand where water came from tells us a little bit about how common life is in the universe."

All water in the solar system – whether on planets, in comets or meteorites, or icy moons like Europa – contains a certain amount of deuterium – an isotope of hydrogen that has an extra neutron attached.

Ripped apart

Ice found between stars is even more deuterium-rich, so it was long suspected that it was the source of our solar system's heavy water. But the young solar system was so violent and full of radiation that any incoming ice should have been ripped apart, recombining later into water – according to this picture.

But when Cleeves and her collaborators built a model of the early sun, they found that this explanation didn't stand up. After their model scrapped all of the interstellar ice, they found that oxygen was being locked up in frozen carbon monoxide. And there wasn't enough ionised, deuterium-rich hydrogen being produced either. In short, the nascent solar system wouldn't have had the ingredients for water with the high levels of deuterium we see.

Instead, interstellar ice must have made its way into planets, moons and comets intact. Cleeves and her colleagues calculate that as much as half the water in Earth's oceans and possibly all of the water found in comets came from this ancient source.

Ice isn't the only thing out there in interstellar space – there's also organic material, says Fred Ciesla, a planetary scientist at the University of Chicago. If this interstellar stuff went into the formation of our solar system's planets, then it probably forms part of planets around other stars too – boosting the chances that many planetary systems formed with the raw ingredients for life.

"It provides the opportunity for organic materials, and the things that are important to the formation of life, to at least be accessible to all planets out there," says Ciesla. "Whether or not it forms into aliens and little green men and women is a whole other story."

Journal reference: Science, DOI: 10.1126/science.1258066

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Make tough tasks seem easier by zapping the brain

My, what big eyes you have – you must be trying really hard. A study of how pupils dilate with physical effort could allow us to make strenuous tasks seem easier by zapping specific areas of the brain.

We know pupils dilate with mental effort, when we think about a difficult maths problem, for example. To see if this was also true of physical exertion, Alexandre Zenon at the Catholic University of Louvain in Belgium, measured the pupils of 18 volunteers as they squeezed a device which reads grip strength. Sure enough, the more force they exerted, the larger their pupils.

To see whether pupil size was related to actual or perceived effort, the volunteers were asked to squeeze the device with four different grip strengths. Various tests enabled the researchers to tell how much effort participants felt they used, from none at all to the most effort possible.

Comparing the results from both sets of experiments suggested that pupil dilation correlated more closely with perceived effort than actual effort.

Mind over matter

The fact that both mental effort and perceived physical effort are reflected in pupil size suggests there is a common representation of effort in the brain, says Zenon.

To see where in the brain this might be, the team looked at which areas were active while similar grip tasks were being performed. Zenon says they were able to identify areas within the supplementary motor cortex – which plays a role in movement – associated with how effortful a task is perceived to be.

Next, they used a non-invasive method called transcranial magnetic stimulation to block activity in that area as people repeated the task. "When we disrupted this area, there was a clear drop in the perception of effort," says Zenon. In other words, the participants made the same actual effort but to them, it seemed significantly easier.

The implications are really interesting, says Zenon. "I don't know how practical it would be to use stimulation to make some activity seem less effortful, but in theory it's possible. For now, we are just trying to understand what mental effort actually is."

Journal reference: Frontiers in Behavioral Neuroscience, DOI: 10.3389/fnbeh.2014.00286

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Ageing societies will be better for the planet

There is a silver lining to the ageing of societies in the West. Amid fears of rising healthcare costs, soaring pension bills and a declining workforce, it seems that ageing could return Germany to carbon dioxide emission levels not seen since before the 1950s.

The average age is rising in most nations, as people live longer and birth rates fall. This process is most advanced in industrialised nations. Germany has a fertility rate of 1.4 children per woman and a life expectancy of 80. Half the population is aged 46 or older, a world record shared with Japan. Germany has 60 per cent more people aged over 65 than under 14, and a a report earlier this year for the German finance ministry warned that the costs of ageing and declining income-tax revenues could cut the country's GDP by 3 per cent.

But greyer could mean greener, according to a detailed study of consumption patterns by age group. Fanny Kluge of the Max Planck Institute for Demographic Research in Rostock, Germany, and colleagues found that per-capita CO₂ emissions in Western countries rise steadily as children become adults and as adults become more affluent. But after the age of 60, emissions decline by roughly 20 per cent when individuals retire and travel less.

Universal trend

As a country's population as a whole ages, it will follow the same pattern, says Kluge. As baby boomers grow into middle age, the country's emissions soar, but when the proportion of pensioners becomes greater, emissions fall. The dip will be accentuated by any drop in population, if death rates exceed birth rates.

Kluge calculates that since 1950, ageing has caused a 30 per cent increase in German CO₂ emissions. But, after 2020, "as the proportion of people older than 80 continues to increase and the population size shrinks, emissions will decrease and reach pre-1950 levels by 2100".

The positive effects don't stop there, Kluge says. The alarming scenario in which pensioners outnumber those in work may have been overstated. The proportion of those aged over 65 in Germany is expected to rise from 21 per cent today to 33 per cent by 2050. But the need to support more pensioners will be compensated by a rising proportion of working women and a fall in the proportion of children.

Health costs will rise, for sure. The average female life expectancy in Germany by 2050 could be 90 years. But, says Kluge, recent studies show that most of the bills for looking after old people occur in the last two years of life, regardless of their actual age. Healthy life expectancy, say the authors, is going up as fast as total life expectancy – but they admit rising rates of dementia could yet confound that trend.

Although the world faces the prospect of 1.5 billion pensioners by 2050, the new work suggests that may not be so bad after all.

Journal reference: PLoS ONE, DOI: 10.1371/journal.pone.0108501

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