Law human: February 2015

Saturday, February 28, 2015

Britons may have imported wheat long before farming it

Video: Britons may have imported wheat long before farming it

Prehistoric people living on the British Isles were more than hunter-gatherers: they were bakers, too, a discovery suggests. They seem to have been eating wheat for millennia before it was cultivated in the region.

A find of plant DNA challenges the assumption that the grain didn't arrive until agriculture took hold there around 4000 BC. People were in fact enjoying flour imported from mainland Europe some 2000 years before this.

"Rather than being cut off as the commonly held view states, these hunter-gatherers had trade links to distant agricultural communities," says Robin Allaby from the University of Warwick, UK.

Allaby and his team's claim is based on a discovery at an undersea site around 12 kilometres from the Isle of Wight, off the coast of southern England. In the Mesolithic Age – some 10,000 to 5000 years ago, before farming emerged – the area was above the waves and was the site of a shipyard. Using pioneering techniques to analyse the sediment dug from beneath the sea floor, they found plentiful wheat DNA from this era – 2000 years earlier than any other signs of wheat previously found in the UK.

However, the lack of the pollen in the samples suggests that nobody was growing wheat here. And as the closest wheat-farming communities were probably in southern Europe or the Near East, getting a loaf of bread would have required a substantial trek. Occasional examples of trade across Europe from this time do exist, but this is the first evidence that hunter-gatherers were willing to travel long distances for rare foodstuffs.

Fond of flat bread

The fact that no husks or seed casings turned up in the mud suggests that these communities got their wheat in the form of flour. So it is likely that the boat builders had a fondness for flat breads to complement their protein-rich diet of game and foraged nuts and plants, says Allaby.

Dorian Fuller from University College London believes that the rare grain was probably a status symbol rather than an important part of hunter-gatherers' diets. Much like the spice trade that flourished in more recent times, the exotic and distant origins would have made wheat highly desirable for those looking to show off.

Valuable foodstuffs were often the first commodities to be traded over long distances, as later crops – African sorghum arriving in India and wheat in China, for instance – bear out. Fuller sees no reason why it would be any different for Mesolithic communities.

Pete Rowley-Conwy of Durham University, UK, is deeply sceptical of the new finding, which flies in the face of the accepted view of how grain cultivation and consumption spread throughout Europe, though. "It is not impossible," he says, "but the distances involved make the whole idea extremely unlikely."

He is unwilling to throw out a consensus from thousands of previous finds, based on just one study.

Journal reference: Science, DOI: 10.1126/science.1261278

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5 things you're dying to ask about head transplants

Read about the proposed head transplant surgery? Here are answers to questions on the tip of your tongue. And no, we can't defrost all the cryogenic heads

Read more: Click here to read a longer version of this story

What's the difference between brain and head transplants?
A brain transplant would involve removing the brain from the skull and placing it in a donor skull. It is more difficult than a head transplant because of the complex surgery to separate the brain and blood supply without damaging delicate tissue.

Could the transplant technique work for a cryogenically frozen head?
No. The proposed technique requires a healthy human head and brain. It is not yet known whether it is possible to "defrost" a cryogenically frozen head and resurrect healthy brain tissue.

Would the surgery be psychologically damaging?
Some people who have received face or limb transplants mourn the loss of their old body part or feel that their self image is conflicted. Studies show that inputs from our body, such as a heartbeat or rumbling stomach, can influence our will power, emotions and language Movie Camera . Who knows whether the person who comes out of the operating room would be the same as the one who went in.

Would there be any benefits apart from getting a healthier body?
If the recipient head is older than the donor body, they may get a rejuvenating boost. Infusions of young blood can raise physical endurance and cognitive function in older animals. A study is now seeing if young blood has the same effect on people with Alzheimer's.

I'm a registered organ donor. Could my body be used for this?
Each country has its own rules. In the UK, joining the register would not automatically allow your body to be used. "If a person needs something not specified on our forms, we would ask a potential donor's family to consent," says an NHS spokesperson. "We would only approach a family if the planned procedure had ethical approval."

Read more: "First human head transplant could happen in two years"

Leader: "Body swaps sound like fantasy, but pose real questions"

This article appeared in print under the headline "The big questions"

What colour is the dress? Here's why we disagree

(Image: Swiked/http://bit.ly/17Cbamm)

It could be simultaneously both the biggest and the smallest controversy to hit the internet since, well, ever. What colour is the dress? A Tumblr user uploaded a picture of a dress, saying that they were having an argument about what colour it is. Is it white and gold or blue and black? Buzzfeed republished it and it broke even their records for traffic.

In fact the dress is blue and black.

So why does the picture appears white and gold to some people, and blue and black to others?

There are already many explanations, and most are wrong. But fear not, New Scientist can explain it.

(Image: Adrian Pingstone)

You've probably seen optical illusions like this one above.

Believe it or not, the two squares, A and B, are exactly the same shade of grey. Because there are cues in the image telling you to imagine that B is in shadow, you interpret it as a light coloured square, made darker by being in shadow.

But as Erin Goddard from Macquarie University in Sydney, Australia, points out, a similar trick can be done with colours too. Look at this version below:

(Image: Dale Purves)

Both squares are grey, but you see one as yellow and one as blue. It happens because in both cases you unconsciously correct for what colour you think the source of light is.

We do that all the time to get by in the world: the reason you see a piece of white paper as white regardless of whether you're outside (under the blue sky) or inside (under red-tinted candle light) is because you shift the colour of the paper in your mind back to white – you white balance it. Or in technical terms, you "discount" for the "colour of the illuminant".

In the illusion above, on the left you correct for a light source you think is yellow, making the grey square appear blue. And on the right you do the opposite.

So now to that dress. The key thing is that we are correcting for an imagined light source, just as in the example above. But there are two features of this picture that make it very difficult to interpret, which means people are likely to see it differently.

Firstly, the dress is actually a complicated mixture. If you find the RGB values of the gold/black, they come out as a "yellowish/gold/brown" says Bart Anderson from the University of Sydney. Meanwhile, the "white/blue" is a mixture too. "If you look at the image itself – the colours in the image – they are gold and very light blue," he says, clearly taking a side in the controversial dispute.

The second feature that makes it ambiguous is that there are not many cues in the picture to tell you how to interpret the colour of the light source. You can't even tell if it's in shadow or not, which could make all the difference, says Goddard.

"In addition to making things darker, shadows often 'change' the colour of part of a scene – eg if there's a sunny scene, the direct sunlight is quite yellow, but areas in shadow are mostly lit by skylight, which is quite blue," she says. "Artists know about it – they know to add blue to shadows to make them more convincing."

Without cues telling you how to correct for the light source, people can be left fumbling and possibly just randomly fall into one category. And once you see it that way, it's hard to change.

"It's actually consistent with a few different interpretations but rather than seeing it as 'oh, it could be this or it could be that' you tend to just make a guess and stick with that until you've got evidence to the contrary," says Goddard.

It can then be very surprising to hear that it's not the same for everyone. Goddard says a similar thing happens with the well-known spinning ballerina. You can see it either way, but it once you see it one way or the other, it's very hard to switch.

Anderson says that feature of this illusion struck him. He started off as a white/golder. In fact, when New Scientist first contacted him he thought it was a hoax. "Do either of you see anything remotely black about this dress?" he asked me and another researcher over email. But after playing with the image for a while switched to a black/bluer. "I can't get my original percept back. Usually when this happens, I can see both. So it's very interesting."

But it could also be something to do with people's internal biases, says Anderson. "People may have different estimates of the colour balance – ie, what counts as 'neutral'," he says. Since this illusion so strongly splits people into different camps, it could be interesting to learn about the nature of those inherent biases. "Although it's not clear how it will tell you much more than that yet," he says.

Thursday, February 26, 2015

Why your brain needs touch to make you human

Touching communicates emotions (Image: Meyer/Tendance Floue)

Being touchy-feely isn't just nice – caresses build social worlds from families to sports teams and may even give us our sense of self

FIST bumps and bum slaps, high fives and back pats – most sports teams can't keep their hands off each other. Watch a group of players on a winning streak and you'll see a lot of touching. Keep a tally and it might even give you a way to pick the champions. The teams at the top of the rankings at the end of the US National Basketball Association season, for example, engage in more hands-on interaction from the start than those who ended up at the bottom, according to work by a group at the University of California, Berkeley. Not only does touch seem to signal trust and cooperation, it creates them.

Examples like this are ...

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Ancient black hole had an inexplicable growth spurt

THAT sure is a flaming big hole. Astronomers have discovered a black hole with a mass 12 billion times that of the sun. It seems to have reached that size when the universe was less than a billion years old, which creates a puzzle. Current models suggest that it could not have grown so big so soon after the big bang.

Xue-Bing Wu of Peking University in Beijing, China, and his colleagues found the black hole by searching through data from sky surveys, looking for bright objects called quasars.

One candidate, J0100+2802, looked particularly promising, so the team used telescopes in China and the US to analyse its light. By measuring how much the light had been stretched out by the expansion of the universe, they calculated that it is 12.8 billion light years from Earth.

Quasars, which emit vast quantities of light, are thought to surround black holes and be powered by gas heating up and glowing as it falls into the hole. Measuring the properties of this gas can in turn determine the black hole's mass. J0100+2802 is about four times as bright as the previous brightest quasar at this distance, and its black hole is a monster at 12 billion times the mass of our sun (Nature DOI: 10.1038/nature14241).

There are bigger black holes out there, but it is the age of this one that's troubling. It reached this size just 900 million years after the big bang – which in black hole terms isn't very long.

"Everyone thinks of black holes as these great dangerous things that swallow up anything in their vicinity," says Daniel Mortlock of Imperial College London. But that's not the case. "If you try to force-feed it you get a traffic jam on the way in and it gets very dense."

This heating creates quasars, but if too much material falls in too quickly, it becomes hot enough to force new material out of the gravitational pull of the black hole. Such an early giant breaks the theorised growth limits, says Wu. "It either requires very special ways to grow the black hole, or requires that a huge seed black hole existed when the universe was less than 300 million years old."

Another explanation is that small black holes somehow form in clusters in the early universe, and grow massive by merging with each other rather than sucking up gas, says Mortlock. But large black holes made this way won't glow, so we can't see them.

None of these solutions is fully supported by existing theories, says Mortlock, so we will probably need bigger telescopes to peer even further back into the past. "You're coming up with theories to try to explain what are pretty close to the most distant objects we can see," he says.

This article appeared in print under the headline "Giant black hole grew too fast"

Wednesday, February 25, 2015

Renewable energy poised to overtake nuclear in the UK

A wind of change is blowing through the UK's power stations. Renewable sources of energy like wind turbines could soon generate more electricity than nuclear power stations.

The contribution of renewables towards keeping the lights on more than doubled from 6.8 per cent in 2010 to 14.9 per cent in 2013, according to the Office of National Statistics. Nuclear power, at 19 per cent, is in slow decline – no new power stations have been built since 1995, when it contributed more than 25 per cent of the UK's electricity.

Onshore wind turbines delivered a third of the country's renewable electricity in 2013, with offshore wind rising fast and accounting for 21 per cent. A plan approved last week for the world's largest offshore wind farm – 400 turbines covering more than 1100 square kilometres of the shallow waters of the Dogger Bank in the North Sea – would add almost two-thirds to existing offshore generating capacity of 4000 megawatts.

The UK has invested £14.5bn in wind turbines since 2010, supporting 35,400 jobs, says Ed Davey, secretary of state for energy and climate change. Renewables are also reducing our reliance on foreign imports of fuel, he adds.

"Wind has already outperformed nuclear on several days over the past 12 months," says Gordon Edge of Renewable UK, which represents the wind and marine energy industry. "The gap is closing fast. Renewables are set to overtake nuclear on a permanent basis by the end of next year."

Powers that be

Other significant renewable UK electricity sources include bioenergy – where co-firing, burning plant biomass together with coal, leads the way – hydroelectricity and solar power which, despite the increasing visible presence of photovoltaic cells on the nation's roofs, lags behind.

However, most electricity still comes from fossil fuels – 37 per cent from coal and 28 per cent from natural gas.

The Office of National Statistics, a government agency, says the UK is "on track" to meet its European Union green energy targets, which cover transport and heating as well as electricity. Use of natural gas for heating buildings has been stable for 20 years as better energy efficiency measures have compensated for more homes. And transport – the biggest single user of energy for the past 25 years – is still overwhelmingly driven by oil.

Energy use is in long-term decline in the UK. Consumption in the past three years has fallen back to the levels last seen in the mid-1980s, says the Office of National Statistics. This is thanks to industry slashing its power consumption by half since 1980, and to the adoption of energy efficiency technology.

Declining energy use and a greening of energy supply have combined to help bring down the nation's carbon dioxide emissions by 22 per cent since their peak in 1990, despite a 66 per cent inflation-adjusted increase in GDP during that time.

A New History of Life shows we're not extinction-proof

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Book information
A New History of Life: The radical new discoveries about the origins and evolution of life on Earth by Peter Ward and Joe Kirschvink
Published by: Bloomsbury
Price: $30/£20

Shark Bay, Australia: cyanobacteria help form modern stromatolites (Image: Frans Lanting/National Geographic Creative)

Hubristic humans should heed the boom-and-bust vision of Peter Ward and Joe Kirschvink's book, a grand synthesis of all that is known about evolution

THE most brilliant innovation in the history of our planet was also the most catastrophic. Some 2.4 billion years ago, a microbe evolved to extract energy from sunlight. That chemical reaction exploited the abundance of carbon dioxide in Earth's early atmosphere. As greenhouse gas levels fell, our planet became a great snowball, enduring a mass extinction from which our young world barely recovered.

This cycle of boom and bust is typical of life on Earth. In fact, mass extinction is one of life's only constants, as Peter Ward and Joe Kirschvink show in A New History of Life. The other constant, counteracting life's destructive exuberance, is that "times of crisis promote new innovation". Each of us is "the descendant of survivors tempered by catastrophe and quenched by time", they say.

The two are well qualified to make such generalisations, and to take up the broader challenge of synthesising all that has happened since the first nucleic acids began replicating 4 billion years ago. Their interests and expertise are complementary. Ward is a palaeobiologist at the University of Washington, whose research and writing focuses on mass extinction; Kirschvink is the geobiologist at the California Institute of Technology responsible for the Snowball Earth hypothesis. Moreover, a new history of life is much needed since the last grand synthesis, by palaeontologist Richard Fortey, was published in 1998.

As an update, Ward and Kirschvink's book is stimulating. Unfortunately, it is blighted by poor organisation and sloppy writing. Some of the same basic science is explained two or three times in different sections, and the prose seems rushed, making for a less-than-pleasant read. That said, A New History of Life is fascinating when the authors write about subjects close to their hearts, such as Snowball Earth.

The oxygen habit

That deep chill lasted over 100 million years, freezing the oceans and killing most organisms. One survivor was the cyanobacteria responsible for "inventing" photosynthesis and for the "great oxygenation event" that squandered atmospheric CO₂.

While the planet was frozen, the microbes bided their time in hot springs. As volcanism slowly replenished CO₂ and the greenhouse effect thawed out the great snowball, cyanobacteria flourished again, guzzling the precious CO₂ and snowballing the world for a second time.

What extracted Earth from this vicious cycle, explain the authors, was the evolutionary enticement of oxygen: "Evolution would have immensely favored any organism that could use oxygen, since no other molecule lets the chemical reactions we call life take place faster, with more precision, and liberate as much energy as those where oxygen is used."

The microbe that got oxygen metabolism right – mastering one of the most noxious of gases – became the basis of all animal life, subsisting inside every cell as mitochondria. By a similar process, cyanobacteria evolved into the photosynthetic chloroplasts inside plants. Evolution channelled crisis into opportunity, ultimately allowing for the multicellular complexity of forests and people. Snowball Earth episodes offer a perfect example of how perversely creative mass extinction can be.

Yet once we were on oxygen, there was no kicking the habit. Nearly 2 billion years after the great oxygenation event, a precipitous drop in O₂ caused the greatest extinction of all time. Colloquially known as the Great Dying, the Permian extinction eliminated 90 per cent of species on Earth. Purple sulphur bacteria suffocated the oceans, burping up toxic hydrogen sulphide gas. Atmospheric oxygen plummeted by two-thirds. Simultaneously surging greenhouse gas levels turned the climate tropical. As Ward and Kirschvink note, this rising heat increased the oxygen demands of animals at the worst possible moment. Many of the terrestrial species that didn't die took to the cooler seas. Largely abandoned, the land was wide open for any organism that could adapt. Dinosaurs made the leap.

The first crucial change was to go bipedal, allowing the reptiles to breathe while they walked. More impressively, write Ward and Kirschvink, dinosaurs developed "the most sophisticated and efficient set of lungs... the world has ever seen". Summarising research Ward first published in his 2006 book Out of Thin Air, the authors make a compelling case that these formidable lungs were decisive in the dinosaurs' ascent, at the expense of our mammalian ancestors. With a richer supply of O₂ in the low-oxygen Triassic, the reptiles simply had more energy, positioning them to dominate the Jurassic and Cretaceous.

But the dinosaurs could not survive the aftermath of a major asteroid impact. Darkened skies killed the vegetation that fed their massive bodies, leaving the world to scrappy mammals. "Sooner or later," say the authors, "evolution, competition, and the natural changing of our Earth and sun as they age will make any body plan obsolete." No advance is absolute. Evolutionary innovation is only as good as its fitness for a niche.

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Rats can't get drunk after a dose of oxytocin hormone

Video: Rats taking cuddle chemical don't get drunk

If you want to counteract the effects of getting drunk, a big dose of the so-called "cuddle-chemical" oxytocin might be the answer.

Oxytocin Movie Camera has important roles in sexual behaviour and social bonding, and has previously been investigated as a way to help wean alcoholics off drink.

While studying this effect in rats, Michael Bowen from the University of Sydney noticed something strange. Rats that had been given oxytocin didn't seem to get drunk. "Those that had the oxytocin were up and moving about as if they hadn't had any alcohol at all, whereas the ones that didn't have oxytocin were quite heavily sedated," Bowen says.

This effect was confirmed in a second experiment, in which half the rats were given an injection of oxytocin straight into the brain, at a level about 150,000 times what would normally be found there. They were then given alcohol, after which researchers tested their motor control and reaction times. Oxytocin seemed to completely counteract the effects of the booze – even when a rat had consumed what would be equivalent to about one and a half bottles of wine in humans. "The rats that had received oxytocin, as well as the alcohol, were virtually indistinguishable from the rats that hadn't received any alcohol at all," says Bowen.

This could be thanks to the brain's GABA receptors, where alcohol is thought to exert its intoxicating effects. Bowen's team found that oxytocin was binding to two parts of these receptors, blocking alcohol from getting there. "It was actually preventing alcohol affecting these sites in the brain that make you intoxicated."

But the effect isn't limitless. When the team gave some rats the equivalent of about a bottle of vodka, the oxytocin wasn't enough to keep them awake. This is because at very high doses, alcohol starts to bind to GABA receptors that are inside neural connections, called synapses, where oxytocin can't reach them.

Sobering up

"As exciting as it is to think this new application of oxytocin might allow people to have a few too many drinks at their lunchtime meeting and come back and be more productive in the afternoon, the significance does extend far beyond that," says Bowen. The real promise of the finding is in treating alcohol-use disorders, he says. "While you might think that a drug that makes you feel less intoxicated might make you drink more, the opposite seems to be the case with oxytocin."

"In addition to blocking alcohol intoxication, it has been shown that oxytocin reduces alcohol consumption, prevents the development of tolerance to alcohol and reduces the severity of alcohol withdrawal," says Bowen.

"The effect is quite dramatic," says Zoltan Sarnyai from James Cook University in Queensland, Australia. "If it holds up in humans, from a practical point of view, oxytocin could be an ideal drug."

Bowen plans to investigate this use of oxytocin in humans soon, but because it is such a large molecule, it may be hard to get enough of it through the blood-brain barrier. However, he says that by finding which part of oxytocin binds to the GABA receptors, it should be possible to design smaller chemicals to do the same job.

Journal reference: PNAS, DOI: 10.1073/pnas.1416900112

Stunning fossils: Fish catches fish-catching pterosaur

Two predators, two prey, but only three animals (Image: 2012 Frey, Tischlinger)

The swooping pterosaur snatched a fish from the water, only to be caught by a much bigger fish leaping into the air

Discovered: Solnhofen, Germany, 2009
Age: 155 million years
Location: Wyoming Dinosaur Center, US

The pterosaur flew just above the water of the tropical lagoon. Snap! It snatched a small, herring-like fish from the water and began to swallow it. But the noise attracted a predator. Up popped Aspidorhynchus, a sleek fish about 60 centimetres long. The fish leaped out of the water and grabbed the pterosaur by its left wing as it was flying. All the animals then splashed down into the water.

But the Aspidorhynchus had bitten off more than it could chew. It didn't have wide jaws and cutting teeth capable of dealing with such large prey. Its narrow jaws, ending in a pointed ...

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Tuesday, February 24, 2015

Cure for love: Chemical cures for the lovesick

ROSES are red, violets are blue, when you reject me, what can I do? As we discover more about love's neural basis, we are getting closer to a way of curing its ills.

While many might be wary of a chemical cure for heartbreak, there is an argument that such anti-love solutions could help people struggling with suicidal or delusional thoughts because of unrequited love, or those in the clutches of unrelenting grief. The morals of the use and misuse of such drugs are complex (see "Cure for love: Should we take anti-love drugs?"), but ethics aside, what could a cure for love look like?

First things first: what is love? For Shakespeare, it "is an ever-fixed mark, that looks on tempests and is never shaken". For neuroscientists, it's less poetic: a neurobiological phenomenon that falls into three subtypes: lust, attraction and attachment – all of which increase our reproductive and parental success.

Each aspect is grounded in a suite of overlapping chemical systems in the brain. There are ways to diminish each of them, says Helen Fisher at Rutgers University in New Jersey, but they aren't always palatable.

Take lust. Ever found yourself obsessing over the tiniest details of a person? Their hair, say, or the number of kisses in a text? This tunnel vision resembles some of the symptoms of obsessive compulsive disorder, so Donatella Marazziti at the University of Pisa in Italy, compared the brains of 20 people in the first throes of love with those of 20 people with OCD.

Both groups had unusually low levels of a protein that transports serotonin – a hormone involved in regulating mood – around the brain. Retesting the lovers a year later revealed that their serotonin levels had increased, and that they no longer reported an obsessive focus on their partners.

Drugs that boost serotonin can offer relief to people with OCD, so it's reasonable to think that they could also help to dampen lustful feelings. These drugs include antidepressants called selective serotonin reuptake inhibitors, which are known to blunt extreme emotions and make it harder to form romantic bonds. This is an unwanted side effect for people with depression, but for those seeking to detach from someone, it could be welcome.

What if it's not lust but a lasting bond you want severed? Several chemicals play a role in helping us form attachments, and animal studies are showing how we could manipulate them to do just that.

The prairie vole is famously monogamous – it forms one life-long bond. However, when Larry Young at Emory University in Atlanta, Georgia, injected female voles with a drug that blocked either dopamine or oxytocin, they became polygamous. "This suggests you might be able to block oxytocin and sever a long-term attachment," says Young.

But oxytocin is important for all relationships, not just romantic love. You might cure your broken heart, but is it worth impairing all your other relationships?

Young's team has also shown that blocking corticotropin-releasing factor (CRF), a hormone involved in the stress response, stops the depressive behaviour that prairie voles exhibit when their partner dies. Young doesn't recommend blocking CRF for unrequited love, but he says it could be helpful to relieve the depression that comes with persistent grief.

Since love shares some of the neural underpinnings with addiction, you will need to replace your fix of oxytocin or dopamine. You can do this without popping a pill, says Young. Exercise ramps up dopamine levels, and bodily contact and social interaction can raise oxytocin.

Should we expect to see quick-fix solutions offered off label or in some anti-love black market? "I think there would be a real market, but I certainly don't recommend it," says Young.

Ultimately, time is the answer, says Fisher. Her team is the first to study the neural mechanisms involved as love fades away. She has found that people who are pining after a lost love have greater brain activity in the ventral pallidum, involved in attachment, than people who were happily in love. This activity diminished over time, suggesting that their attachment also waned.

Other groups are trying to help people with post-traumatic stress disorder replace a memory with another that is less emotionally fraught. "Hypothetically, you could imagine a similar therapy being used to dampen the memory of love," says Fisher. One day it might even be possible to use brain stimulation to decrease activity in the ventral pallidum, to speed up the healing effects of time, she says.

Until then, it seems what your mother told you about heartbreak still rings true: you can't beat time and a little love from someone new.

Leader: "Cure for love: Should people be able to marry robots?"

Read more: "Cure for love: How to fix a broken heart"

Were early seas transformed by sponge microbiome?

If ever there was proof of the power of small things, surely this is it. Last year, came the suggestion that sponges transformed Earth's deep oceans 750 million years ago, turning them into an oxygen-rich haven for life. Now it seems tiny bacteria living inside the sponges also played a part in the drama.

The discovery was an accident, says Fan Zhang of the University of Maryland in Baltimore. He and his colleagues happened to notice microscopic phosphate granules spread throughout the tissue of three different species of Caribbean sponges they had in the lab.

Living inside the sponges were bacteria that suck phosphorus out of seawater and precipitate it into granules, which Zhang's team suggests may be used by sponges. Phosphorus is an essential but rare nutrient for ocean life. Like all marine organisms, sponges need it to survive but can't extract it from the water – but the bacteria can help them out. Meanwhile, bacteria need the sponges to pump vast amounts of seawater over them so they can extract more phosphorus. So, Zhang says, the sponges and bacteria live in symbiosis.

Working together in this way, the two have evolved a hyper-efficient system for extracting phosphorus – the ultimate limiting factor for life in today's oceans, given that it is one of essential building blocks of life's molecules.

Early life link

Sponges and many of their symbiotic bacteria have been around for hundreds of millions of years, since the very early days of animal life on Earth.

Researchers suggested last year that sponges could have triggered key events in Earth's history, some 750 million years ago, when life was evolving rapidly in the oceans.

Around that time it seems the deep oceans became rich in oxygen – a transformation traditionally credited with driving the Cambrian explosion, the sudden flourishing of all the different types of animal shapes we know today.

Nicholas Butterfield of the University of Cambridge and his colleagues proposed last year that early animals, specifically, sponges, led to a surge in deep ocean oxygen, not the other way around.

They point out that sponges can survive on very low levels of oxygen, so would have been kings in the early ocean. "What do sponges do? They are absolutely fantastic pumpers and filterers," says Butterfield. "Invent something like a sponge [750 million years ago] and the world is their oyster. They have no competition. And now, for first time water is being pumped and filtered."

Sudden slug

As the sponges pumped, they aerated the deep oceans with oxygen produced by photosynthesising organism floating in the upper layers, says Butterfield. Phosphorus in the water would have reacted with all that oxygen to form a hard phosphate precipitate that is not much use to living things. Thus the sponges and their microbiome may have been responsible for making phosphorus the ultimate limiting factor, by converting it into phosphate and so restricting the amount of the element available to oxygen-consuming life-forms, and hence further boosting oxygen levels in the deep.

Evidence for a sudden surge in phosphate is found in fossil deposits from around this time, many of which are preserved in the stuff. "There has never been a good explanation for why, in the first time in millions of years, we get a huge slug of phosphate," says Butterfield.

He says Zhang's study offers a compelling explanation for how the sponges and their symbiotic bacteria might have sequestered and regulated phosphate in the early ocean.

"It has largely been thought that early animals evolved rather passively in response to physical and chemical changes on the early Earth," says Daniel Brady Mills of the University of Southern Denmark in Odense. "Studies like this suggest that early animals could have actually exerted significant controls over Earth's ancient chemistry."

Journal reference: PNAS, DOI: 10.1073/pnas.1423768112

Tiny bat makes home in a carnivorous plant

(Image: Merlin Tuttle/Science Source)

BATS roost in big groups in caves. Wrong! If you're a Hardwicke's woolly bat, you prefer to sleep in a more luxurious – and private – place.

Kerivoula hardwickii roosts inside tropical pitcher plants. These carnivorous plants usually attract insects, but Nepenthes hemsleyana lacks the scents that others have, so few bugs are lured in. Instead, it benefits from the faeces of this tiny bat, which provides more than a third of its nitrogen and may be crucial to the plant's survival.

"This is the only bat species that has ever been found roosting in pitchers," says Caroline Regina Schöner, whose team discovered the bats in 2009. "These bats managed to find a niche that no one else is occupying."

To take these images, Merlin Tuttle waded through tropical forest peat swamps on Borneo. Once he had found an occupied plant, he would spend a few hours taming a bat before snapping it from his portable studio, which provided protection from heavy rains. "It only takes a small fraction of a second for a bat to either enter or emerge, so capturing the action at just the right moment is a real challenge," says Tuttle.

Within a few days, the bats had learned to bump against his nose when they wanted him to give them some mealworms. "We were quite amazed at the intelligence of such tiny animals," Tuttle says. "Contrary to common misconceptions, bats in general are gentle, highly intelligent and trainable."

This article appeared in print under the headline "Home, sweet plant"

Monday, February 23, 2015

Stunning fossils: Snake eating baby dinosaur

Who's eating who? (Image: Sculpture: Tyler Keillor, Photo: Xiimena Erickson)

Snake fossils are extremely rare, and this one was petrified just as it was about to eat a dinosaur hatchling

Discovered: Gujarat, India, 1986
Age: 68 million years
Location: Geological Survey of India

Unlike some dinosaurs, the giant, long-necked sauropods did not care for their eggs. Adults have never been found near nests, so it seems that sauropod hatchlings had to fend for themselves from the start. And that left the way clear for predators to feast on them as they emerged.

One of these predators was a 3.5-metre-long snake called Sanajeh indicus. Towards the end of the age of the dinosaurs, one decided to raid a nest of a sauropod eggs, perhaps attracted by the noise of hatchlings breaking out of their shells.

Sanajeh could not open its mouth wide like modern egg-eaters and other snakes, says Jeffrey Wilson ...

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$1 billion bank hack: stopping the next cyber heist

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A hacking gang is suspected of stealing vast sums from banks worldwide for two years with apparent ease. How can a repeat be averted?

Good news! A major hack you don't have to worry about! Unless, that is, you happen to be an executive or security employee at one of the hundreds of banks targeted by the group that has come to be known as Carbanak or Anunak.

If you are, then you have a problem, because these hackers – and no doubt others to come – aren't targeting banking consumers but the internal systems of banks, silently monitoring them and subtly defrauding them. Unlike most cybercrime, this wasn't a hold-up, but a bank heist – the kind that could ultimately affect both consumers and governments. And that's why we should all be paying attention.

Skill-wise, the attack is at a similar level to November's Sony Pictures hack. (So much for the FBI's claim that the Sony hack was unprecedentedly scary.) It was a long-term effort, professionally executed, and required a fair amount of organisation and coordination to pull off.

These aren't just script kiddies stealing people's credit-card numbers. The hackers managed to compromise the systems of banks, but rather than immediately grabbing information and alerting targets to their presence, they would quietly observe the inner workings and transactions for months. They were then in a position to subtly manipulate the system in order to cash out. According to a report from software-security company Kaspersky Lab, the hackers obtained up to $1 billion through dozens of attacks over the past two years.

Systems compromised

There are several things worth noticing. One is that the initial compromises of the systems were possibly the simplest and dumbest aspects of the attacks. The hackers would enter a system through the tried-and-true method of "phishing" – sending emails to employees that purport to come from a trusted sender inside the company. (Attacking a specific organisation through this approach is called "spear phishing".) The employee opens an attachment in the email, which immediately compromises the system.

These hacks used Windows and Office document files that, when opened, injected malware into the target's computer, more or less giving the hackers total control.

What they did with this control, however, was more sophisticated. The hackers monitored the keystrokes of the computer and took screenshots every 20 seconds, giving them a very clear picture of the daily internal workings of a bank. And instead of attacking customer accounts, which are more closely monitored for fraud, the hackers went after internal fund mechanisms.

First, they inserted fake transactions into the SWIFT transfer network to distribute money to other banks and credit cards. Second, and rather ingeniously, they attacked ATMs directly. Seizing central control of the banks' ATMs, they set them to spit out cash spontaneously and then had their accomplices ("money mules," as Kaspersky terms them) visit the terminals at the right time to collect the dosh.

The exact scope of the attack is still up for debate. According to Kaspersky, the group targeted banks in 30 countries, though primarily in Russia, and obtained about $1 billion. A more detailed, earlier report from December by Group-IB and Fox-IT confined the attacks to Russia and placed the damage in the hundreds of millions.

Phishing threat

Until banks can keep their employees from opening bad links and files inside phishing emails, they must simply assume that they are quite vulnerable to attack.

In terms of efficiency, these attacks are vastly more impressive than most hackers can ever hope to achieve. Though the efforts required time, each individual compromise raked in $10 million. Each hack remained undetected for its duration, and some banks were compromised multiple times.

Because almost none of the money was tied to any particular customer's account, the thefts were mostly invisible to consumers, so no individuals raised red flags.

Plus, consumers face bigger threats from the more recent Dyre and Dridex banking Trojans, which hijack browsers to obtain user credentials, even managing to defeat two-factor authentication in some cases.

For banks and other institutions, though, Carbanak's sophisticated attacks are scary for two reasons. Along with the Sony hack, these kinds of breaches entail obtaining long-term and in-depth access to targeted systems in order to cause the most damage, financial or otherwise. That means there are two facets of security that companies need to worry about.

First, there's that primitive initial compromise. It's somewhat embarrassing that a phishing attack can end up compromising more or less all of a bank's systems, but that's exactly what happened here. There was no complicated exploit of some unknown security hole or cracking of passwords; an employee just needed to open an attachment (usually a Word document) in a phishing email, which then exploited known vulnerabilities in unpatched Office software. These vulnerabilities were patched by Microsoft years ago (most recently in March 2014).

So, at a minimum, banks need to keep their software updated with security fixes, but beyond that, they also need to scan all incoming attachments and clamp down on the ease with which employees open them.

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Exclusive: Jane Hawking tells her Theory of Everything

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Video: The Theory of Everything - Exclusive preview

IT IS 1963, and we're at a student party in Oxford. A young man approaches a young woman.

"I'm a cosmologist," he says.

"What's that?"

"It's religion for intelligent atheists."

You will have seen him on The Simpsons and Star Trek but you've never seen him like this. Stephen Hawking, the world's most famous living scientist, as a young, able-bodied, ambitious student, chatting someone up.

This is the beginning of The Theory of Everything, the story of Hawking's exceptional life framed by the blossoming – and eventual withering – of romance with his first wife, then Jane Wilde.

(Image: Focus Features/Photoshot)

Straight away we are tipped off to the broad tone that the movie will take on their relationship: one of his godless cosmology, and of her more conventional Christianity. But how true to life is it? And if it isn't, how much does that matter?

Eddie Redmayne and Felicity Jones are outstanding in the roles of Stephen and Jane. Redmayne especially is extraordinary in his portrayal of how Hawking is affected by motor neuron disease. By the end, when he is almost completely paralysed and unable to speak naturally, everything must be conveyed visually. Redmayne accomplishes this task brilliantly.

Jones plays the indomitable Jane with quiet restraint and subtlety. This is fitting since her performance, and the role Jane played in his life, are always at risk of being overlooked.

The film skimps on the science, but nit-picking over the accuracy of science in movies is rarely worthwhile. It's too much to hope that a biopic can convey the depth of what Hawking did. It's technical stuff, after all – and even Hawking's bestselling pop science book, A Brief History of Time, tops lists of books we don't finish.

But no one had used quantum physics to examine what happens in black holes before Hawking. He discovered that contrary to the belief that nothing can escape the gravity of black holes, a small amount of radiation can in fact get out.

In the movie, that discovery – of what would come to be known as Hawking radiation – is conveyed as a eureka moment that happens when Hawking is staring into a fire. The reality – the proof coming only after months of intense calculation – shows that this stuff is difficult, even for the world's smartest man.

The film's director, James Marsh, has experience in making films based on scientific experiments. His 2011 documentary film Project Nim was the story of a baby chimp reared as a human child; it was a compelling story of science, but science gone very wrong.

Despite the immense richness of the subject matter here, his telling of Hawking's work doesn't communicate the same complexity. The Theory of Everything splashes around on the shore, but doesn't go deep into what Hawking actually did.

In some ways, another new movie, Interstellar Movie Camera , does better. This may be because it has Kip Thorne, one of Hawking's longest-standing physicist friends, as executive producer and science adviser. For a mainstream movie, it manages a far more thorough exploration of the science of black holes.

So does Marsh succeed in telling the story of the central relationship in Hawking's life? To find out, we spoke exclusively to Jane Hawking, who was divorced from Stephen in 1995 and whose book, Travelling to Infinity: My life with Stephen was adapted by Anthony McCarten to form the core of the movie.

Jane and Stephen Hawking in 1965 (Image: © Jane Hawking, reproduced courtesy of the author)

Stephen has said he found the film "broadly true". What do you think?
The parts of the film that were true to life were particularly moving, some of them quite overwhelming, but I did not relate to the fictitious episodes or anything outside my own experience.

How was that first meeting with Stephen?
There was no exchange about cosmology or religion, except that Stephen explained that he had just begun research in cosmology in Cambridge. Instead, he gave a lively account of his encounter with the Oxford examiners who called him for a viva after Finals.

There's a scene in the film about the May Ball, where Stephen explains that the men's shirts are fluorescing under UV light because of Tide washing powder. The next day, there's a packet of Tide on your doorstep. Did that happen?
It isn't really the sort of thing that anyone would make up!

Has your role as a conduit in explaining Stephen's work been overlooked?
Although a linguist, I was always interested in, and fascinated by, Stephen's explanations of his work, and proud of his discoveries and achievements. There was a time when I could explain gravitational collapse and subsequently black holes to an amateur audience, but only in practical not mathematical terms.

I did the first proofreading of A Brief History of Time, and when it came to writing my memoir, I consulted many scientific friends, so that contrary to what many critics supposed and were churlish enough to voice, I did actually write the scientific sections myself.

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Female ejaculation comes in two forms, scientists find

What do you think of when you hear the words "female ejaculation"? Come to think of it, the answer may be best kept to yourself. You may have heard that it was banned from being shown in British porn films last year. But what exactly is it?

Researchers have now come a step closer to defining this controversial phenomenon, by performing the first ultrasound scans on women who express large amounts of liquid at orgasm.

Some women express liquid from their urethra when they climax. For some, this consists of a small amount of milky white fluid – this, technically, is the female ejaculate. Other women report "squirting" a much larger amount of fluid - enough to make it look like they've wet the bed.

A few small studies have suggested the milky white fluid comes from Skene glands - tiny structures that drain into the urethra. Some in the medical community believe these glands are akin to the male prostate, although their size and shape differ greatly between women and their exact function is unknown.

Climax in the lab

To investigate the nature and origins of the fluid, Samuel Salama, a gynaecologist at the Parly II private hospital in Le Chesnay, France, and his colleagues recruited seven women who report producing large amounts of liquid - comparable to a glass of water - at orgasm.

First, these women were asked to provide a urine sample. An ultrasound scan of their pelvis confirmed that their bladder was completely empty. The women then stimulated themselves through masturbation or with a partner until they were close to having an orgasm - which took between 25 and 60 minutes.

A second pelvic ultrasound was then performed just before the women climaxed. At the point of orgasm, the squirted fluid was collected in a bag and a final pelvic scan performed.

Even though the women had urinated just before stimulation began, the second scan - performed just before they climaxed - showed that their bladder had completely refilled. Each woman's final scan showed an empty bladder, meaning the liquid squirted at orgasm almost certainly originated from the bladder.

A chemical analysis was performed on all of the fluid samples. Two women showed no difference between the chemicals present in their urine and the fluid squirted at orgasm.

The other five women had a small amount of prostatic-specific antigen (PSA) present in their squirted fluid - an enzyme not detected in their initial urine sample, but which is part of the "true" female ejaculate

PSA, produced in men by the prostate gland, is more commonly associated with male ejaculate, where its presence helps sperm to swim. In females, says Salama, PSA is produced mainly by the Skene glands.

Beverley Whipple, a neurophysiologist from Rutgers University in Newark, New Jersey, says that the term female ejaculation should only really refer to the production of the small amount of milky white liquid at orgasm and not the "squirting" investigated in this paper. "This study shows the other two kinds of fluids that can be expelled from the female urethra - urine alone, and urine diluted with substances from the female prostate," she says.

"This study presents convincing evidence that squirting in women is chemically similar to urine, and also contains small amounts of PSA that is present in men's and women's true ejaculate," says Barry Komisaruk, also at Rutgers.

"This study helps to reconcile the controversy over the fluids that many women report being released at orgasm," he adds. "There are evidently two different fluids, with two different sources. Whether either of these fluids plays a physiological role - that is, whether they serve any adaptive function, is not known."

Florian Wimpissinger at Rudolfstiftung Hospital in Vienna, Austria, suggests that the presence of PSA in some women's squirted fluid and not others might be because the emissions from the Skene glands could travel into the bladder at orgasm. It may also have something to do with the known variation in size and shape of the glands, or be that some women don't produce PSA in the first place.

Every woman capable

Why some women experience these different types of ejaculation and others don't is not yet clear, says Salama, but he believes every woman is capable of squirting "if their partner knows what they are doing".

For now, Salama is not investigating that particular avenue, but instead working on a protocol to test whether the kidneys work faster to produce urine during sexual stimulation than at other times, and if so, why.

The ban on female ejaculation in UK porn is based on the fact that the British Board of Film Classification (BBFC) considers films which include material featuring "urolagnia" - sexual pleasure associated with urination - as obscene under the UK Obscene Publications Act.

However, the wording of the law actually appears to be referring to squirting - not female ejaculation. So this new paper may support the current legal position, since it shows it is essentially involuntary urination. Presumably, under current UK law, if a woman were to have what is considered a true female ejaculation - the expulsion of a small amount of milky white fluid - and the BBFC were satisfied that this did not contain urea - this act would not be subject to the ban.

Journal reference: The Journal of Sexual Medicine, DOI: 10.1111/jsm.12799

Sunday, February 22, 2015

Stunning fossils: Sauropod flees for its life

Thrill of the chase (Image: 2014 Falkingham et al)

The trail of footprints left by a huge sauropod and a T. rex.-like dinosaur may record a predatory chase

Discovered: Glen Rose, Texas, 1938
Age: 111 million years
Location: Part at the American Museum of Natural History

The massive sauropod fled along the shore closely pursued by a huge predator similar to T. rex. The trail of footprints they left behind survived for over 100 million years.

Exactly what happened is not clear. Roland Bird of the American Museum of Natural History, who discovered the footprints in 1938, thought they showed an actual attack in progress, with the predator running alongside the sauropod and at one point sinking its teeth into the victim, missing a step as it was lifted off the ground.

Modern researchers are more cautious. There is no clear evidence of an attack, says James Farlow of Indiana ...

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Saturday, February 21, 2015

Searching for signs of Mars life could destroy them

Martian minerals could destroy organic compounds, the molecules necessary for life, as we search for them. A new study shows that heating a mineral called jarosite makes it break up organics before we have a chance to observe them, muddying the results from the Martian rover Curiosity.

Mars fans can be forgiven for a sense of déjà vu. The same problem may have plagued the 1976 Viking lander, the first spacecraft to search directly for Martian organics by heating powdered rock in its oven. When it failed to find any, researchers were surprised: comets, meteorites and interplanetary dust particles have been bringing organic material to the Red Planet throughout its history. Why weren't there any to be found?

In 2008, the Phoenix Mars lander suggested an explanation. The lander discovered perchlorates, a compound combining chlorine and oxygen. When heated, perchlorates break down and release an oxygen atom, which splits organic molecules apart. So instead of seeing organics themselves, Viking may have seen the by-products of their reactions with chlorine and oxygen.

"We were wondering if perchlorates were the only minerals on Mars that would have a negative influence on detecting organic compounds," says James Lewis at Imperial College London. Jarosite, a sulphate salt that forms in the presence of acidic water, also gives up an oxygen atom when heated to about 500 ^oC.

Climate shift

The presence of the mineral also marks a shift in Martian climate, when a neutral, drinkable water-rich environment gave way to more acidic conditions. Previous rovers and orbiters have seen jarosite in various Martian locales, and Curiosity, which landed in 2012 and is currently climbing a mountain that preserves Mars's geological history, just reported its first evidence of jarosite earlier this month.

Conveniently for Lewis and his colleagues, jarosite also forms on Brownsea Island in Dorset, UK. "There are micro-environments here that are very relevant to Mars," says Mark Sephton, Lewis's PhD advisor. "We don't have to go all the way to Rio Tinto in Spain or Yosemite in the US to get our samples."

Lewis removed layers of rock rich in both jarosite and organics from cliff faces on the island and brought them back to the lab to grind them into powder and heat them. He heated the powder from 400 to 1000 ^oC in 100 ^oC increments, to find out which compounds appeared at each temperature. This is similar to the technique used in Curiosity's SAM (Sample Analysis at Mars) instrument.

"We never detected the organics we knew were in the sample," he says. Instead, they saw sulphur dioxide, carbon dioxide, carbon monoxide and water – what you would expect if the jarosite reacted with the organics and broke them down into other carbon compounds.

"If Curiosity was doing a similar experiment on Mars, and had a compound with jarosite and organics, it wouldn't be able to detect them," he says.

Curiosity, we have a problem

This isn't just a problem for Curiosity, whose primary mission doesn't include searching for signs of life today. The European Space Agency's ExoMars rover, due to launch in 2018, will hunt for life – and it also uses a heating technique to hunt organics.

There is hope, though. Jarosite and related minerals come in many different forms, some of which don't fall apart until they reach much higher temperatures. The key, Sephton says, will be choosing the right samples to analyse. It might also be possible to interpret the decomposition products to see if organics were there to begin with.

"It's turning out to be more of a detective story than we first imagined," Sephton says. "It's making us work for our science."

Jennifer Eigenbrode of Curiosity's SAM team says she's not surprised by the results, but they don't mean SAM won't see evidence of organics if they are actually there. That's because organics come in many forms. Depending on their size and how concentrated they are in the Martian soil, it might be difficult to see them directly – but easy to see their by-products once sulphates or other minerals destroy them.

"Personally, I think if we were to see evidence of high temperature combustion due to the presence of oxygen coming off of a mineral, as they suggest from sulphates, it might be a blessing in disguise," she says. "The key is having a variety of experiments in your back pocket that you can pull out and search for the organics in different ways. That's what SAM is doing."

Journal reference: Astrobiology, DOI: 10.1089/ast.2014.1160

Stunning fossils: Turtles caught in the act

No prizes for guessing what this pair were up to (Image: 2012 The Royal Society)

You don't need to be a fossil expert to work out what these two turtles were up to just before they died

Discovered: Messel Fossil Pit, Germany, 1987
Age: 47 million years
Location: Senckenburg Natural History Museum, Frankfurt

The French famously call it the little death. But for this pair of mating turtles, the little death became a big death. As they sank down into the depths of a lake in their post-coital bliss, they reached toxic waters and perished. Their fossil remains leave no doubt that they died in the act of mating.

Around 30 fossils of mating insects have been found, most of them caught in amber. But the turtles, Allaeochelys crassesculpta, are the first ancient vertebrates to be caught in the act. They lived in a volcanic lake in what is now ...

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Friday, February 20, 2015

Ancestry of first Americans revealed by a boy's genome

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The genes of a boy who died 12,600 years ago show that all indigenous people in the Americas seem to be descended from the same group of ancestors

WE MAY never know who the Anzick child was. Why he died, just 3 years old, in the foothills of the American Rockies; why he was buried, 12,600 years ago, beneath a huge cache of sharpened flints; or why his kin left him with a bone tool that had been passed down the generations for 150 years.

One thing, however, is certain: his afterlife is anything but ordinary. This week, geneticists announced that the boy is the earliest ancient American to have his entire genome sequenced. Incredibly, he turns out to be a direct ancestor of most tribes in Central and South America – and probably the US too – as well as a very close cousin of Canadian tribes.

"It's crazy," says Eske Willerslev of the University of Copenhagen in Denmark, who led the genomic analysis. "Finding someone who is directly ancestral to the entire population of a continent – that just does not happen. I don't think it would ever happen in Europe, or in Siberia. There are very few places where this could happen."

"The reason," he says, "must be that this skeleton is really close to the source – really close to the 'Adam'. I think that is the only explanation."

The find offers the first genetic evidence for what Native Americans have claimed all along: that they are directly descended from the first Americans. It also confirms that those first Americans can be traced back at least 24,000 years, to a group of early Asians and a group of Europeans who mated near Lake Baikal in what is now Siberia. And it dispels a controversial theory that the Americas were first populated by west Europeans who somehow crossed the Atlantic Ocean.

The boy was discovered in Montana in 1968, when diggers working on land owned by the Anzick family accidentally ploughed into a huge cache of stone tools. The flints were typical of the Clovis period, a short archaeological period in North America lasting from 13,000 to 12,500 years ago. Beneath them lay a handful of bone artefacts and a skeleton.

Clovis artefacts are scattered all over the western US. Archaeologists largely believe that the first Americans arrived by a land bridge from Asia about 15,000 years ago, and some went on to develop Clovis tools (see "A history of the first Americans in 9½ sites").

Willerslev and his colleagues were able to extract enough viable DNA from the boy's badly preserved bones to sequence his entire genome.

They then compared this with DNA samples from 143 modern non-African populations, including 52 South American, central American and Canadian tribes.

The comparison revealed a map of ancestry. The Anzick child is most closely related to modern tribes in Central and South America, and is equally close to all of them – suggesting his family were common ancestors. To the north, Canadian tribes were very close cousins. DNA comparisons with Siberians, Asians and Europeans show that the further west populations are from Alaska, the less related they are to the boy.

Fully sequenced genomes remain rare, so the bulk of the analysis was done by looking at genetic markers known as single nucleotide polymorphisms or SNPs. To confirm the pattern, Willerslev and his team sequenced full genomes from three contemporary Mayan and Karitiana individuals in Central and South America.

The findings offer genetic confirmation that the first Americans crossed the land bridge that once stretched from Siberia to Alaska across the Bering Strait.

"The Clovis population seems to be more closely related to South Americans than to native North Americans," says David Reich of Harvard Medical School in Boston. "That's telling you that the Clovis sample seems to have occurred after the initial split of the lineages that gave rise to native South Americans and native North Americans."

Unfortunately, long-standing tensions between US tribes and scientists mean there is no significant genetic data available from these peoples (see Leader, "An ancient genome alone can't heal long-standing rifts"). Having that data, says Reich, could help determine which groups lie on either side of the North and South American family tree.

In November, Willerslev published the genome of another ancient boy, the 24,000-year-old Mal'ta boy, from the shores of Russia's Lake Baikal. The boy's DNA showed he descended from a mating between early Asians and proto-Europeans, and that he is related to modern South Americans. Like modern South American DNA, the Anzick DNA is a mix of Mal'ta and other Asian DNA, pointing to a "source" population for the first Americans, probably in far eastern Siberia (see map).

But how many first Americans were there, and did they come all at once or as a slow trickle? "The most likely scenario is that a single migration of people into the heartland of North America around 15,000 years ago gave rise to the Clovis and their descendants, which includes modern Native Americans," says Mike Waters of Texas A&M University in College Station, a co-author with Willerslev on the latest study. "This is supported by the archaeological and genetic evidence."

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Crunch time for Mars One to avoid two-year delay

Mars One, the Dutch firm hoping to colonise the Red Planet, has just a few months to decide whether it will launch its first unmanned mission to Mars in 2018. If it misses the deadline, the entire high-risk enterprise will be delayed another two years.

While national space agencies think manned missions to Mars are something for the distant future, Mars One says it can establish a permanent colony on the planet by the mid-2020s, funded by turning the whole thing into a reality TV show and selling the media rights.

In 2013 the firm announced a partnership with aerospace firm Lockheed Martin to build an unmanned Mars lander based on an old NASA probe, Phoenix, that would extract water from the surface and test solar panel technology. It also signed a separate contract with UK firm Surrey Satellite Technology (SSTL) to build a communications satellite to relay live video from the lander.

But yesterday, SpaceNews reported that work on these two missions had been suspended – a claim Mars One CEO Bas Lansdorp denies. "We're currently reviewing the results of the work our suppliers did and are preparing for the next contracts, so we're simply in between contracts," he says. "The 2018 robotic mission is still the very very highest priority for Mars One."

Tough timeline

But meeting the 2018 launch date will be tricky, he admits. "If we cannot make this deadline we are always flexible in moving another two years," he says. "That's a decision that we will have to make before the summer." The Mars One timeline has already slipped, as initial plans called for a communications satellite in 2014.

Lockheed Martin and SSTL confirmed to New Scientist that they have completed their initial concept study contracts with Mars One and are awaiting notification to proceed to the next step. "That's normal, that's how these things go," says SSTL's Joelle Sykes. "Just because you've done the study, doesn't mean you will actually get the work, it might go out to tender to other companies."

Meanwhile, Mars One recently announced it has narrowed the pool of applicants down to 100 astronaut candidates who will start training for what will be a one-way trip, assuming it gets off the ground. Lansdorp says the firm will start building a simulation of the astronauts' future Mars base in the Netherlands later this year. "We are in negotiation with the construction company, but the actual construction hasn't started."

The plan to sell the TV rights is on shaky ground, too. Lansdorp says a deal with media company Endemol, which produced Big Brother, has fallen through, and it will instead work with an as-yet unnamed company to produce a documentary series.

Clarification, 20/02/2015: When this article was first published, it implied Mars One was working with a specific media company. This has now been amended.