the-BA : Science News Digest

Gorilla (Image copyright: istockphoto.com)

In the news this week: humanity’s survival at risk, the genetic influence on food choices, and a cold spot in space sheds light on the Big Bang. Plus, flame-haired Neanderthals...

Let’s get the doom-laden news out of the way first.

UK scientists warned that current predicted temperature increases caused by global warming could trigger a mass extinction, following a study which showed that four out of five mass extinction events which occurred on Earth in the past 520 million years were associated with greenhouse phases (warmer, wetter conditions) rather than icehouse phases (cold, dry conditions).

The researchers compared estimates of sea surface temperatures against marine and land diversity over a period that covered almost the entire fossil record. They found that global diversity was high during periods that were cool and low when warm.

‘Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner,’ said co-author Dr Peter Mayhew, of the University of York. ‘If our results hold for current warming, the magnitude of which is comparable with the long-term fluctuations in the Earth's climate, they suggest that extinctions will increase.’

The mass extinction that wiped out some 95 per cent of all species 251 million years ago was among those occurring during a greenhouse phase.

‘We could - at worst - be experiencing that in the next century - only a few human generations down the line,’ Dr Mayhew told BBC News. ‘We need to know why temperatures and extinctions are linked in this way.’

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Meanwhile, the Times revealed that 29 per cent of the world’s 394 primate species are at risk of extinction as a result of threats such as bushmeat hunting, illegal trade in animals and habitat loss.

60 experts from 21 countries worked to assess primate numbers, producing a report ‘Primates in Peril: the World’s 25 Most Endangered Primates – 2006-2008’. Gorillas, lemurs and orangutans were among those listed.

Russell Mittermeier, President of Conservation International, one of the groups involved in the research, said: ‘You could fit all the surviving members of these 25 species in a single football stadium. That’s how few of them remain on Earth today.’

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And the news got worse. According to the United Nations, ‘humanity’s very survival’ is at risk because of the rate at which we have used the Earth’s resources over the past 20 years, reported the Times.

400 scientists conducted an environmental audit for the international organisation, and found that, worldwide, each person requires a third more land to supply their needs than the Earth can supply. The UN’s Environment Programme said the ‘point of no return’ was fast approaching and that urgent action was needed.

While climate change was highlighted as a pressing problem, the condition of fresh water supplies, agricultural land and biodiversity were deemed to be of equal concern.

The conclusions of the Global Environment Outlook (Geo-4) report were peer-reviewed by 1,000 further experts in their field. Its publication marks 20 years since the seminal Brundtland Commission conference that placed the idea of sustainable development at the heart of the UN, noted BBC News. However, according to the new report, most environmental indicators have taken a downward trend since then and more resources and will are required from governments to stop the situation from worsening.

The full report can be downloaded from the BBC News website, and the Times lists some of the key facts and figures as well as ‘20 reasons why the human race may not survive’.

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After all that, you may be feeling rather bleak about the future. But most of us, reports the Times, are natural optimists who tend to think the future will turn out alright, even when there’s evidence to the contrary.

Scientists have now identified two regions of the brain that seem to play a role in positive thinking: the rostral anterior cingulate cortex and the amygdala.

Researchers from New York University asked volunteers to think of either positive or negative future events, while their brains were scanned using functional magnetic resonance imaging. They discovered that levels of activity in the two specific brain regions were much higher when participants were thinking of positive events. The activity seen also correlated with the volunteers’ mental outlook, as determined by a psychological questionnaire.

‘Understanding optimism is critical as optimism has been related to physical and mental health. On the other hand, a pessimistic view is correlated with severity of depression symptoms,’ team leader Professor Phelps said.

Since abnormal activity in both parts of the brain is more common among people with depression, it is hoped that the work will lead to new insights into the origins of the mood disorder.

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Turning our eyes to space: scientists may have found the first evidence for a cosmic defect known as a ‘texture’ that would provide support for the theory that different particles evolved as the expanding universe cooled.

Physicists generally accept the Big Bang as the best model for the origin and evolution of the universe, believing that it was initially very hot and dense and cooled as it expanded. Many think that during the first early moments of the universe, whilst it was hot, all particles had identical properties, only developing unique behaviours and differentiating into, for example, quarks, neutrinos and electrons, as the universe cooled – a process known as symmetry-breaking.

Back in the 1990s, Professor Neil Turok from the University of Cambridge proposed that such a cooling event would create defects in the vacuum of space known as ‘textures’, and that these should be detectable as hot and cold spots in the background cosmic microwave radiation.

Now, it seems that one such cold spot has been identified by researchers at the Institute of Physics of Cantabria. After comparing their measurements with theories of how a cold spot could arise, using the Cambridge COSMOS supercomputer to perform large scale simulations, Professor Turok and colleagues found that the cold spot was consistent with a ‘texture model’ and that there was only a one per cent chance that the observation was not evidence of a texture. He said that further tests would be carried out in the next few years to conclusively prove or disprove the hypothesis.

‘The concept of symmetry-breaking is the most fundamental concept in our explanation of the particles and forms we see in nature,’ Professor Turok told the Telegraph. ‘The possibility that this is a texture is very exciting. If it is, it will revolutionise our understanding of how the fundamental symmetries between the particles and forces were broken as the universe emerged from the Big Bang. It would be the first observational evidence that symmetry-breaking really happened as the Universe emerged from the Big Bang.’

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Other space news in brief:

The US space shuttle Discovery, which launched from Florida on Tuesday, safely reached the International Space Station. During their two-week construction mission, the crew will install the ‘Harmony’ unit to the space station – the first expansion of the living and working space since 2001.
(BBC News)

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Later in the week, China launched its first lunar probe. The Change orbiter is due to map the moon’s surface in 3D and analyse lunar dust during its one-year mission. China then aims to land an unmanned rover on the moon by 2012, and an astronaut by 2020.

It is not alone in its lunar ambitions: India is planning a mission next spring, while Japan launched its first probe last month.
(The Guardian)

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According to the Telegraph, one of the great unsolved mysteries of planetary science – the origin of Saturn's rings – may be one step closer to a solution, thanks to analysis of images taken by the Cassini spacecraft.

Scientists from the University of Colorado observed eight distortions in the planet’s outermost A ring. Publishing their work in Nature, the scientists say that the distortions were created by boulder-sized objects that they believe were the result of multiple collisions during the last 200 million years.

Dr Miodrag Sremcevic wrote: ‘It seems unlikely that moonlets [boulder-sized objects] are remainders of a single catastrophic event that created the whole ring system, because in this case a uniform distribution would emerge. Instead the moonlet belt is compatible with a more recent break up of a body orbiting in the A ring.’

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International auction house Bonhams is offering up fragments of collisions that occurred closer at hand. Some of the rarest and most celebrated meteorites in the world are expected to go under the gavel for several million dollars. Lots include the only meteorite ever documented to have killed something – it landed on a cow in Venezuela in 1972.
(The Guardian)

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Twin studies have revealed that our genes, not just our upbringing, play a big part in our food choices.

By comparing identical twins to non-identical twins, scientists are able to determine the likelihood that characteristics are due to ‘nature’ or ‘nurture’. Researchers from King’s College London studied the food preferences of more than 3,000 female twins aged 18 to 79, and found that genetics influenced a person’s inclination towards a particular food group by between 41 and 48 per cent. In particular, a taste for garlic and coffee were strongly linked to a person’s genes.

’For so long, we have assumed that our upbringing and social environment determine what we like to eat,’ said Professor Tim Spector, who led the research. ‘This has blown that theory out of the water – more often than not, our genetic make-up influences our dietary patterns.’

The findings could have an impact on healthy eating campaigns, reported BBC News, since they suggest that a genetic predisposition to eating less fruit and vegetables could make some people more resistant to health messages than previously thought.

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A survey of 204 scientists, conducted in advance of a Battle of Ideas festival debate ‘What are the Barriers to Science in the 21st Century’, suggests scientists feel their work is over-regulated, and that this is actually damaging public confidence in research by giving the impression that most of it is dangerous or ethically dubious.

While most accepted that some ethical scrutiny and regulation is needed, 37 per cent of respondents felt that increasing regulation of animal experiments, and work involving embryos and human tissue, does more harm than good to the field’s reputation. Only 15 per cent think it has a positive influence.

Many agreed that scientists could do more to communicate their work to the public, and more should be done by universities to promote this, according to 51 per cent of those surveyed. There was also concern that too much emphasis is placed by the Government on achieving economic benefits from research.

Tony Gilland of the Insititute of Ideas said that, while the respondents were self-selected, their views reflect a clear mood that science is excessively regulated, reported the Times.

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And finally…

When you see illustrations of how Neanderthals might have looked, traditionally they’re pictured as having brown hair. But now, new genetic evidence suggests some Neanderthals were redheads.

In modern people, red hair is caused by a mutation in the MC1R gene. BBC News reports that a team of researchers have now been able to isolate a version of the MC1R gene from Neanderthal bones found in Italy and Spain, finding a unique variant of the gene in two separate Neanderthals.

To test its effect on hair and skin colour, the Neanderthal variant was inserted into a human melanocyte cell – the cell that gives skin, hair and eyes their colour by producing the dark pigment melanin. It exhibited the same loss of function as the human MC1R variants that give red hair.

While dark hair and skin are needed in equatorial regions to protect against UV damage by the Sun, in areas where there are lower levels of sunlight, such as Europe, you find pale skin, along with red or blond hair.

Dr Carles Lalueza-Fox, lead author of the paper published in Science, said: ‘Once you go out of Africa, the selective pressure from UV radiation disappears. So any mutation that falls into the MC1R gene is allowed to survive and spread through a population. In Neanderthals, there was probably the whole range of hair colour we see today in modern European populations, from dark to blond right through to red.’

The fact that the Neanderthal version of the gene isn’t found in modern humans suggests to Dr Lalueza-Fox that they didn’t interbreed.