New Scientist reports

What can evolution tell us about domestic violence? Two researchers in the US suggest such violence has ancient origins and that establishing evolution’s role could help to better identify those at risk. Others argue that the research makes simplistic assumptions, and warn that some people will interpret the research as an excuse for violence.

Each year more than 500,000 women in the US alone report to the police violent attacks by current or former male partners. There is a reason why domestic violence is so widespread, says David Buss, an evolutionary biologist at the University of Texas in Austin: it carries a selective advantage, tied with reproductive success. In other words, men who are violent are trying to make sure that their partner has his child and not another man’s. “There are very predictable circumstances in which violence occurs,” says Buss. “For instance, with the threat of sexual infidelity or the threat of relationship termination.”

For instance, in a study of 8000 women some 14 per cent of those with a history of domestic violence agreed that their partner “is jealous and doesn’t want you to talk to other men” – less than 1 per cent of women who experienced no violence agreed with the statement.

Buss predicts that domestic violence will be more likely when a man has a female partner of higher “mate value” – a woman who earns more, is more intelligent or is considered more physically attractive than him. He says men in such circumstances may resort to violence to deter the woman from straying, or else to reduce her own perception of her value by lowering her self-esteem.

“Buss’s hypotheses are certainly plausible,” says biologist Barbara Tschirren at the University of Zurich in Switzerland. “We know from studies in animals that conflicts among family members are ubiquitous.”

“For many people, saying something might have been adaptive in the past is difficult to separate out from saying it is good or right or natural,” says Robert Brooks, an evolutionary biologist at the University of New South Wales in Sydney, Australia. “But we are the product of the traits that made our ancestors good at reproducing, including many quite abhorrent traits.”

Eating a strain of gut-loving bacteria reduces anxiety-like behaviour in mice – a finding that suggests a spoonful of microbes could help stress levels go down in people too.

The human gut is home to about 1000 trillion bacteria, which prevent pathogenic bacteria infiltrating our bowels. Once thought to simply prevent diarrhoea, gut bacteria have recently been linked to autism, reducing the symptoms of Parkinson’s disease, and treating eczema. Now it seems these microbes can also reduce stress in animals and humans.

New Scientist reports that John Bienenstock at the McMaster University in Hamilton, Ontario, Canada, and colleagues fed mice for 28 days on a broth laced with Lactobacillus rhamnosus – a bacterium often used in probiotics – and subjected them to a barrage of stress tests.

Bacteria-fed mice showed less anxious behaviour and had lower levels of the stress hormone corticosterone than mice fed regular broth. The brains of these rodents showed predictable alterations, such as reduced expression of receptors in the amygdala – a region of the brain associated with anxiety.

So how do probiotics affect the brain?

The researchers reckon the bacteria rely on the vagus nerve, which connects the gastrointestinal tract to the central nervous system. When the team severed the nerve in the bacteria-fed mice, their behaviour – and the expression of brain receptors – became just like the mice fed regular broth. It’s possible that chemicals produced by bacteria interfere with the nerve’s activity.

Mark Lyte at Texas Tech University in Lubbock, who was not involved in the study, believes these findings are relevant to humans since small-scale studies have already found that probiotics can reduce anxiety in humans.

Talk about an excuse to delay “growing up” – the adolescent brain is still being sculpted into its adult form continues throughout our 20s.

New Scientist reports that as children, we overproduce the connections – synapses – between brain cells. During puberty the body snips away some synapses while allowing others to strengthen. Over a few years, the number of synapses roughly halves, and the adult brain emerges.

Or so we thought. Pasko Rakic at Yale University and colleagues found that the brains of adults in their 20s are still subject to synaptic pruning. Rakic’s team analysed post-mortem tissue from a brain region called the prefrontal cortex (PFC) in 32 people aged between 1 week old and 91 years. Specifically, they calculated the density of dendritic spines – the tiny projections that protrude from the neuron’s long dendrites, each of which facilitates communication with other neurons through a synapse.

As expected, Rakic’s team found that spine density increased rapidly during infancy, reaching a peak before the 9th birthday. It then began to fall away as pruning began. Intriguingly, though, spine density did not plateau after adolescence, as might have been expected, but continued to fall gradually until the late 20s.

“You should not give up learning just because you’re in your 20s – it isn’t too late,” says Rakic.

To read more head to New Scientist .

New Scientist reports

THERE are more cows than people here in Nirranda South, three hours south-west of Melbourne, making it the perfect spot to test a technology that remains hugely controversial.

I am at a facility run by Australia’s Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC). If anyone can convince the public that carbon capture and storage can reliably reduce carbon dioxide emissions it’s these guys. Even Friends of the Earth, Australia – which opposes the approach – has grudging respect for the research done here.

Wherever permeable and porous rock is capped by an impermeable layer, a natural gas store may form. Such stores can trap gas for tens of millions of years, making spent oil and gas fields a logical choice for industrial CO2 storage.

But these spent fields are small, and can store only so much CO2 – up to 900 gigatonnes worldwide, according to the Intergovernmental Panel on Climate Change. A more common type of subterranean structure – deep saline aquifers – has the potential to store up to 100,000 gigatonnes. The problem? It is not clear that these aquifers, which naturally house salty water, can keep hold of CO2. “It’s very difficult to predict how the gas will move underground,” says Peter Cook, a hydrologist at Flinders University in Adelaide. That’s where the Nirranda South facility comes in.

To read more head to New Scientist.

To win rock-paper-scissors (RPS) you’ll have to fight an urge to imitate your opponent.

Humans tend to imitate those around them, often without realising it. For example, parents seem tohttp://wendyzukerman.com/wp-admin/post-new.php naturally imitate the facial expressions and gestures of their newborns. But, until now, no one realised how difficult it was to stop being a copy cat.

Richard Cook at the University College of London found that people imitate each other even when it’s not in their best interests – such as playing RPS. Imitation is undesirable here because the only way to win is to present a different gesture to your opponent, he says.

In the study, Cook and his colleagues asked 45 adults to play RPS, either with one player blindfolded and the other sighted, or with both players blindfolded. Each game lasted twenty rounds, and an umpire told the players the previously executed gestures. The winner received £2.50 (US$4), giving an incentive to win, and not draw.

Players who could see had a tendency to imitate their opponents. For example, if a blinded player gestured scissors, 40 percent of the time the sighted player would too. “In contrast, when both players were blindfolded, the rate of draws was exactly that expected by chance,” says Cook. That is, the players would both gesture scissors around 33 percent of the time.

According to Cook, sighted players are automatically imitating their blindfolded opponents. Since blinded players weren’t subject to this bias, they won slightly more often than those who could see.

Timing the response times of eight players, Cook found that in just under 20 percent of the rounds sighted players gestured at least 200 milliseconds after their blinded opponents, giving them enough time to copy, he says. Previous studies found that intentionally copying similar hand gestures takes around 400 milliseconds, and it is “well established” that unconscious responses, in general, are executed faster than intentional ones, he says.

Cook suspects players are automatically imitating their opponents through the activity of mirror neurons, which fire both when we perform an action and see someone else doing it. Previous studies found that playing RPS activates the mirror neurons.

Peter Enticott a neuropsychologist at Alfred Hospital, Melbourne, Australia, who was not involved in the study, suspects that the mirror neurons might activate a default gesture –mimicking our opponent – so players must actively change the gesture to win. As such sighted players who were undecided about the gesture to play, bored or fatigued would be more likely to fall to the default – and draw.

The findings show that our “behaviour can be very rapidly influenced by other’s behaviour” and “we may be powerless to stop this automatic imitation,” says Enticott.

Source: Proceedings of The Royal Society B. doi: 10.1098/rspb.2011.1024

New Scientist reports

Australia’s scientists say their country’s climate debate – never exactly rarefied – has descended into hysterics and extremism, partly driven by the nation’s polarised media.

So, on Monday, in an attempt to restore public confidence in climate science, 200 scientists converged at Parliament House in Canberra, reports the Australian Broadcasting Corporation.

After an address to the National Press Club, the nation’s chief scientist, Ian Chubb, said the national debate on climate science “borders on appalling” and criticised the media for giving undue weight to the views of climate sceptics.

For example, Australia’s Daily Telegraph newspaper, owned by News Ltd, commonly publishes articles describing climate sceptics as “independent-minded people who’ve considered and rejected the economic options presented to them by their social superiors”.

More subtle is the approach of the nationwide newspaper, The Australian, also owned by News Ltd. It continues to report that a carbon tax will damage Australia’s economy despite modelling by Australia’s treasury that found incomes would barely be affected by the imposition of a carbon price and employment would continue to grow.

Australia’s climate scientists have been subjected to a growing number of abusive phone calls and emails. Earlier this month, The Canberra Times reported that the Australian National University in Canberra moved several high-profile climate researchers into more secure buildings following the explicit threats.

Here is a sample of the emails, which have been published by the environmental blogger Graham Readfearn. (Be advised the text contains strong language.)

New Scientist Reports:

Using its web as a gill, the diving-bell spider can live underwater with only occasional visits to the surface.
The arachnid (Argyroneta aquatica) breathes air from a bubble that it grabs from the surface of water using fine hairs on its abdomen. The spider traps the air within a bell-shaped silken web that it constructs underwater and carries around like an aqualung.

It was first described over 250 years ago, but until now biologists didn’t know how it managed to remain underwater without frequent visits to the surface to renew the oxygen in its tiny air bubble.

To find out, Roger Seymour from the University of Adelaide in South Australia and Stefan Hetz of Humboldt University in Berlin, Germany, placed 12 spiders in individual aquaria and measured the oxygen levels within the air bubbles using optical fibres tipped with oxygen-sensitive dye. Seymour also measured the concentration of oxygen in the water outside the bubble.

“The spider’s web acts like a gill,” says Seymour. The silken web allows oxygen to diffuse from the surrounding water into the depleted air, as well as release carbon dioxide.

During the day, Seymour never observed the spiders replenishing their air supply. He believes they can survive underwater for more than 24 hours, allowing them to stay out of sight of predators and prey alike. However, as oxygen levels go down, nitrogen concentrations increase in the bubble. Nitrogen starts to diffuse out into the water, and eventually the bubble collapses.

ON A midnight foray into my kitchen, I flicked on the light and was confronted with a devil’s playground. Cockroaches were fornicating on my pots and dancing on the cooker. They were grinding on my floor and scuttling around my fridge.

Disgusted, I reached for the light switch again. The snack I had hoped for was no longer enticing. But then I saw one critter climbing up the wall. I leaned over to take a look. “How have you come to live in my home?”

Contrary to popular myth, these critters are not especially tough or radiation resistant. Indeed, they are pretty average as insects go. But in the past year, it has been shown that cockroaches do have one special power after all.

To find out what it is, check out New Scientist magazine.