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Genetics and Behavior
Written and researched by Bob Murray, PhD
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Brain's Cheat Detector is Revealed
September 4, 2002
"We think (this facility) develops in all normal individuals, and that it develops in part because our brains were selected to develop this competence," says John Tooby at the University of California, Santa Barbara.
Tooby and his colleagues studied a man who suffered accidental damage to the limbic system, a brain region involved in processing emotional and social information. RM, as he is referred to, performed as well as other people on one set of reasoning problems, did much worse on problems specifically designed to test reasoning about social exchanges.
At its simplest, social exchange runs along the lines of "you scratch my back and I'll scratch yours." Previous work has shown that people, and some animals, are extremely good at keeping a check of who owes whom within a group -- and at spotting and punishing cheaters.
Researchers had proposed that general reasoning abilities could account for this. But RM's deficit suggests that detecting social cheaters depends on specialized neural circuitry, the team says.
Their conclusion is "robust," says Nigel Nicholson, an evolutionary psychologist and Director of the Centre for Organizational Research at the London Business School. "It's essential we have trusting relationships with people in communities where we are highly interdependent for survival and reproduction. Cheat detection is very important," he adds.
The first problems given to RM and the 37 non-brain-damaged controls concerned so-called precaution rules. For example: "If you work with toxic chemicals, you have to wear a safety mask." The second tested social contracts, for example: "If you go canoeing on the lake, you have to have a clean bunk house."
RM recorded a score of 70 per cent on the precaution rule tests -- the same as the controls. But he scored only 39 per cent on the social contract tests, compared with 70 per cent for the non-brain damaged people. Identical tests on two other people with brain damage similar to RM's, but with a slightly different pattern of damage, showed that their social contract reasoning was unimpaired.
"RM's differential impairment indicates that being able to detect potential cheaters may be a separable component of the human mind," the researchers conclude. However, if a region of the brain has evolved to specialise in cheat detection, it should be present in all people, the team reasoned.
Most experiments are performed on people living in modern, western societies, so the team studied people living in traditional, non-developed communities in the Amazonian region of Ecuador. They found that these people were equally proficient at social exchange tasks, even when the problems concerned social rules that were unfamiliar to them.
"What is quite amazing about their performance on cheater detection is that it flies in the face of all ordinary ideas about learning a higher level cognitive skill," Tooby told New Scientist. "People are just as good at utterly unfamiliar rules as they are with rules that are personally and culturally highly familiar."
Read more in New Scientist
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Crow reveals talent for technology
The remarkable toolmaking talent of a New Caledonian crow called Betty has challenged the chimpanzee's reputation as the most proficient toolmaker, besides Man, in the animal world. The bird, one of two kept at Oxford University's zoology field station, fashioned a hook from an ordinary piece of wire -- something even a chimp cannot manage. This species of crow are remarkably adept at both using and making tools. "It's incredibly impressive for something with such a small brain," says Jackie Chappell, one of the scientists studying the birds' behavior. In their home on the Pacific archipelago of New Caledonia, the crows make and use a range of tools including hooks, which they use to extract prey from cracks and crevices. But Betty has now shown that she can design and manufacture a tool from materials with which she has no previous experience. This is unheard of in any other animals, including chimps, say the researchers. Wild crows make hooks from twigs and leaves and do not have access to materials that bend and retain their shape like wire. The captive bird's ability to make the right tool for the job from unfamiliar materials and using quite different manufacturing methods suggests some understanding of the properties of the material and what might be achieved with a hook. The finding raises many questions about how "brainy" these crows are and how their toolmaking abilities evolved. "I don't believe crows have a greater general intelligence than apes but it appears that in this very specific area of cognitive ability crows seem to have an advantage," says Kacelnik.
Read more in New Scientist
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Newborns Can Detect Eye Contact
July 7, 2002
This ability probably helps infants to establish human links and to develop social skills in later life, say scientists. Being able to make eye contact is arguably one of the major foundations for social skills. It is also one of the things that makes us uniquely human.
The fact that healthy babies can do this at such an early age suggests the response is in-built rather than learned. The new research was carried out by an Anglo-Italian team. They showed paired photographs of faces to infants between two and five days old. In one photograph, the eyes were averted. In the other the eyes looked directly forward. The researchers found that the babies looked longer at faces they were able to make eye contact with. Their eyes also looked forward more.
In a second experiment, carried out at Birkbeck, University of London, researchers measured electrical activity in the brain of four-month-old infants. A device called a geodesic sensor net allowed them to study the infant's brain response to the same photographs. The babies showed enhanced processing of the faces with a direct gaze.
"Our research presents the most compelling evidence to date that we are born prepared to detect socially relevant information," said lead researcher Dr Teresa Farroni.
The work raises the possibility of being able to detect if a child is at risk of certain developmental disorders by showing them photographs of faces. In conditions like autism the ability to empathize with others may be impaired. Eye contact too can be affected.
David Potter of the UK National Autistic Society said there was evidence that individuals with autism used different neural circuitry to process faces. "What appears to be a simple perceptual task is difficult for individuals with autism," said. "Research is under way to try to understand the differences in the brains of people with autism which explain this difficulty. If affected individuals spend reduced amounts of time processing faces then they are also failing to develop the social interaction skills that open up the full realm of social life."
Eye contact is just as important in adult relationships as it is with infants. BM
Read more in Proceedings of the National Academy of Sciences
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Just 2.5% of DNA Turns Mice into Men
June 24, 2002
It has long been known that we share about 99% of our DNA with our nearest cousins, the chimps. However a new study shows that we are only 2 1/2% different from our more distant relatives, mice! The new estimate is based on the comparison of mouse chromosome 16 with human DNA. Previous estimates had suggested mouse-human differences as high as 15 percent. The new work suggests that neither genome has changed much since we shared a common ancestor 100 million years ago. Of the 731 genes they located on the mouse chromosome, only 14 did not have a doppelganger in humans. Likewise, there were only 21 genes in the corresponding regions of human DNA that did not turn up in the mouse.
Read more in New Scientist
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Some South American Children Have Partible Paternity
June 10, 2002
According to researchers a number of South American tribes believe that children should have more than one father. The way that women ensure this is to take lovers after they become pregnant. These men then take joint responsibility for the care and provision of both mother and offspring. Statistically these children of multiple, or "partible" paternity are more likely to live longer and be healthier than their single-fathered brethren and siblings. The women also believe that it takes the sperm of more than one man to make a healthy child.
Read more in Uniscience
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The Globe, the World News, and the Examiner are Necessary
May 20, 2002
Don't feel so guilty about thumbing through those tawdry tabloids for the low-down on film stars, the Clintons or the latest sighting of Elvis. They're doing a good and necessary job, so researchers say. The need for gossip is an integral part of our evolutionary inheritance.
A form of gossip may have started when some of our ancient go-getting humanoid ancestors gathered information (the worse, the better) to use against potential rivals, according to a theory by Frank McAndrew, a psychology professor at Knox College in Galesburg, Ill, that appears in the Journal of Applied Social Psychology.
The ones who took no interest in gabbing were cut out of the social loop, McAndrew believes, and had trouble getting mates. "There are things that helped people do well (over) 3 million years of evolution," McAndrew said recently. "People who ate the right foods, people who had sex and people who had important information about the things around them did better."
Our ancestors probably sought to enhance their social standing by spreading information about important people, McAndrew said. "The tabloids and media in general trigger the same reaction," he told the New York Times. "We're tricked into thinking that they're important because we hear about them a lot."
McAndrew asked more than 100 college students to review tabloid magazines and rate the most interesting celebrities. He theorized that students would be most interested in celebrities of the same sex and similar age because they would have been rivals in the ancient past.
Indeed, younger men were most interested in reading bad things about Robert Downey Jr, and women older than 30 wanted the latest on Christie Brinkley's helicopter rides.
"We seek exploitable, damaging information about high-status people," McAndrew and Megan Milenkovic write in the article "Of Tabloids and Family Secrets." At the same time, people share good information about friends and relatives, but "we keep a very watchful eye on friends. The way I think about gossip is that it's sort of an innate part of human nature," McAndrew said. "Sweet foods taste good, sex feels good and gossip is fun. It's rewarding because these are things that helped our ancestors to survive and do well."
Read more in the Journal of Applied Social Psychology
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Our Ancestors Used Drugs to Survive
May 3, 2002
Mind-altering drugs may be so popular because they were once used by our ancestors to survive, two leading anthropologists have argued. Dr Roger Sullivan, of the University of Auckland, and Edward Hagen, of the University of California at Santa Barbara, say there is plenty of evidence that humans have sought out so-called psychotropic drugs over millions of years.
These plants are rich in alkaline substances such as nicotine and cocaine that produce a stimulant effect and may have helped to make life bearable in the most harsh of environments. For example, until recently Australian Aborigines used the nicotine-rich plant pituri to help them endure desert travel without food. And Andeans still chew coca leaves to help them work at high altitudes.
Archaeological evidence shows that drug use was widespread in ancient cultures. Betel nut, for example, was chewed at least 13,000 years ago in Timor, to the north of Australia. Artefacts date the use of coca in Ecuador to at least 5,000 years ago. Many of these substances were potent: pituri contains up to 5% nicotine -- tobacco today contains about 1.5%.
What is more, these drug pioneers sometimes "freebased" drugs by chewing them together with an alkali such as lime or wood ash. This releases the free form of the drug and allows it to be directly absorbed into the bloodstream.
However, Dr Sullivan said that in Pacific cultures where chewing betel nut is still widespread, it is seen more as a source of food and energy than as a drug. Some drugs do have real nutritional value. For example, 100 grams of coca leaf contains more than the US recommended daily intake of calcium, phosphorus, iron and vitamins A, B2 and E.
Dr Sullivan and Dr Hagen believe that eating psychotropic plants may also have played an important role in helping the brain to function properly. They argue that in some particularly tough environments, people's diets may have been so poor that they struggled to produce enough chemicals to help the brain function normally. Consuming plants containing substances that mimic the role of these chemicals could have helped make up for the shortfall.
Dr Wayne Hall, of the University of Queensland, said the theory was plausible. He said: "There is certainly evidence that plants evolved to mimic the neurotransmitters of mammals. But the problem today is that we have much larger doses of much more purified drugs."
Blanket criminalization of any drug is absurd. It has never been shown to work, nor does it reduce the number of addicts, rather it prevents adequate treatment for sufferers. BM
Read more in BBC News
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Germs Are a Teddy Bear's Picnic
February 10, 2002
A new study found that 90 per cent of soft toys examined in doctor's waiting rooms were found to have moderate to heavy bacterial contamination.
Children with infectious diseases are likely to handle these toys while waiting to be seen, says Paul Corwin and colleagues at Christchurch School of Medicine. They may even put them in their mouths, they add. "The next child to play with these toys may thus be exposed to pathogens that could make them ill," the pair write in a paper published in the British Journal of General Practice.
The team tested hard and soft toys taken from six GPs' offices for levels of common bacteria, including a variety of organisms that colonize the gut, such as E. coli. They found that soft toys in particular were prone to carry bacteria, even though most of the doctors' staffs machine-washed the toys at least once a fortnight.
But a cute teddy is likely to do more good than bad, according to Rose Mulligan, of Good Bears of the World, who distributes teddies to sick children in hospitals. "We have been giving bears for 30 years and they have a soothing and comforting effect," she says,
But while no actual evidence of cross-contamination was found, the report's authors say the study raises many questions. "Isn't it time to give the teddy the boot?" they ask.
There is such a thing as over-protection when it comes to germs. For example, the more we insulate our kids from common microbes the higher the rate of asthma. Syphilis began millennia ago as a benign skin irritation which most children were exposed to. It only became the venereal disease killer we know today when a combination of city-living and better hygiene robbed people of the natural immunity provided by the childhood rash. By preventing children from building up a natural immunity to all sorts of mild pathogens we may well be storing up trouble for ourselves in the future. BM
Read more in New Scientist
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Retribution Can Breed Cooperation
January 23, 2002
A group of Swiss economists have found that people will pay to punish -- suggesting that their notions of fairness outweigh selfish considerations. The work may help explain why people cooperate in society.
In an investment game with shared profits, players punish those who do not contribute to the group's good, despite the personal cost. The emotional satisfaction of dispensing justice seems to spur them on. "People say, 'I like to punish,'" says Ernst Fehr of the University of Zurich.
The fear of being fined keeps potential defectors in line, and the power to punish gives willing cooperators a sense of security. These dynamics may explain why early humans banded together into cooperative groups for hunting or warfare.
Explanations of cooperation have tended to focus on what the altruist gets out of it, either through the swapping of good turns or the benefits to family members. "For a very long time in economics and biology there's been an assumption of self-interest," says economist Herbert Gintis of the University of Massachusetts, Amherst. Instead, he says, it seems that egalitarianism is "a basic part of human behaviour."
The research may hold lessons for policymakers attempting to build social cohesion, he believes. Decisions may be more acceptable if they come from within the community and not from a remote central government. "There could be more community-based policing, and more emphasis on shaming [criminals] and rehabilitation within the community," Gintis says.
Cohesion-through-punishment is an influential force in contemporary western society. In industrial disputes, for example, the hatred heaped on strike-breakers cements solidarity, says Fehr.
Conversely, the waning of support for state welfare programs among the US middle class over the past few decades was caused by a perception that too many freeloaders were exploiting the system without fear of detection or punishment, says Gintis. He acknowledges, however, that there are potential pitfalls of using local action to stamp out social scrounging: It might fragment communities into opposing factions, or breed resentment of nonconformists.
There are also problems if fear of punishment cultivates antisocial aims, Fehr points out. "You see it in the Mafia where the threat of reprisal maintains 'omerta,' a code of silence," he says.
Read more in Nature
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Help for Names' Sakes
January 23, 2002
When seeking help from a stranger, ask someone who shares your name: people are more likely to assist a namesake, a study has revealed.
A shared name indicates two people are likely to share genes, so evolution may have taught us to be nice to our namesakes, suggests psychologist Margo Wilson, who carried out the study at McMaster University in Hamilton, Ontario, Canada.
Unusual names are particularly good at eliciting help from others with the same moniker. Which makes sense: the less common a name, the more likely it is that two people sharing it are blood relations.
The US census records 88,217 surnames, 4,275 female names and 1,219 male names, ranked in order of commonness from Mary to Willodean and James to Broderick.
Wilson and her colleague Kirsten Oates took some names from the top of the charts, such as Jones, Smith, Gary and Nancy and some from between positions 100 and 300, including Andrews, Morrison, and the first names Dwayne and Tracey.
The duo set up e-mail accounts for 223 fictitious people bearing all permutations of common and uncommon names. They then posed as a student seeking information on sports team mascots, and sent out nearly 3,000 requests to strangers sharing either one, both or no names, asking for information on their local mascots.
About 12% of those sharing both names responded, compared with less than 2% of people sharing none. A shared first name or surname got a smaller response, but was better than nothing. "When both names were shared, some people showed a great deal of excitement," says Wilson. The phantom namesakes received requests for more information about themselves, and their addresses.
Women were the most diligent respondents. This sex bias is "baffling," comments ecologist Ben Hatchwell, of the University of Sheffield. Surnames pass down the male line, so you'd expect a name to be a much better guide to a man's ancestry than a woman's.
Previous studies in North America showed that women tend to be families' 'kin keepers.' They are better at staying in touch with distant relatives, and have a better knowledge of who's related to whom, although this varies across cultures. Women also seem to be better at social contact in general.
Read more in Nature
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About the Author
Dr Bob Murray is a widely published psychologist and expert on emotional health and optimal relationships. Together with his wife and long-term collaborator Alicia Fortinberry, he is founder of the highly successful Uplift Program, and author of Raising an Optimistic Child (McGraw-Hill, 2006) and Creating Optimism (McGraw-Hill, 2004).
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