Humans' Complex Social Skills Due to Larger Brains

Kate Ravilious for National Geographic News, September 6, 2007

The uniquely human abilities to build relationships with others, talk, and even gossip are all boons of a large brain, a new study says.

Researchers who put human toddlers and great apes through a series of physical and cognitive tests found that human social skills are superior to those of our closest genetic relatives, whose brains are smaller.

But whether we are better at putting our social skills to good use is still a matter of opinion.
"Compared [with] baboons we waste an awful lot of time gossiping about one another," said Joan Silk, an anthropologist at the University of California, Los Angeles, who was not involved in the study.

Superior Social Skills

Esther Herrmann of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues put 106 chimpanzees, 32 orangutans, and 105 young German children through a series of complex tests.

The children were all about two-and-a-half years old and had been speaking for at least a year.
The apes had all been made accustomed to humans.

The researchers designed 16 different puzzles to tease out the differences in ability between humans and apes.

Some of the puzzles, such as tracking the position of a reward under a cup, involved only physical skills. Others, such as selecting the cup that the researcher pointed to, involved social skills such as communication.

The results found that chimpanzees, orangutans, and human children were all equally successful in the physical skills tests.

But the human children were significantly better at the social skills tests—scoring around 74 percent correct on the tests compared to scores of 33 percent from both groups of apes. (Related news: "Monkeys Deaf to Complex Communication, Study Says" [January 22, 2004].)

For instance, the toddlers outperformed the apes on "theory of mind" experiments—the ability to understand that other individuals have their own beliefs and intentions.

Bigger Brain Theories

There are two main theories as to why humans have evolved larger brains than their primate relatives. A huge brain is a serious investment— neural tissue guzzles a lot of energy.

The general intelligence hypothesis suggests that humans' bigger brains make us better and faster at all kinds of skills, such as memorizing, learning, and planning ahead.

The cultural intelligence hypothesis, bolstered by this recent study, says that bigger brains have specifically enabled us to develop more complex social skills.

"This [study] contradicts the general intelligence hypothesis," Herrmann said. "We would have expected to see a difference in physical skills as well if [that] hypothesis was right."

Aside from gossiping, these increased social skills appear to carry strong advantages, enabling humans to sustain relationships with others and help each other out in times of need.

"Our bigger brains enable us to cope with the complexities of social life," said Robin Dunbar, an evolutionary psychologist at the University of Liverpool in the United Kingdom who was not involved in the study.

Migration Factor

No one really knows when or why humans started to develop these enhanced social skills, but there are one or two clues.

"It must have occurred later than one million years ago, as we don't see any increase in brain size before then," lead study author Herrmann said.

One theory is that social skills evolved in response to a more nomadic lifestyle, possibly dating back to when human ancestors began to migrate out of Africa.

"As people began to migrate more they needed to create good relationships with a wider range of people, so that they could beg favors over things like water, food, and access," the University of Liverpool's Dunbar said.

In particular language appears to have been a key development, enabling humans to communicate with others outside of their tribal groups.

Mind-Reading Monkeys

However, humans don't have a complete monopoly on social skills.
A related study published in Science today shows that primates are capable of reading emotions and understanding the intentions of others.

Harvard University's Justin Wood and colleagues tested the ability of cotton-top tamarins, rhesus macaques, and chimpanzees to understand the difference between a deliberate gesture and an accidental gesture.

All the primates showed much more interest when Wood deliberately selected a particular container than when his hand fell accidentally onto a container.

"Humans are not the only ones who can guess what others are thinking," Wood said.

For humans these enhanced social skills have enabled us to spread far and wide, settling in every corner of the world.

But this may have come with some hidden costs, said University of California's Silk.

"The human brain is a really complicated machine that goes wrong with some frequency," Silk said.
"
Mental illness may be the evolutionary cost of this complexity."

Game Theory: Cooperators, Loners, Free Riders, and Punishers

James Fowler is a new kind of political scientist. Specializing in genopolitics, the genetic basis of political behavior, and the evolution of cooperation, he melds the social with the biological, pushing the boundaries of his field to discover, for example, that smoking, obesity, and happiness spread within social networks, and that genes affect voting behavior. A professor at the University of California, San Diego, Fowler is famous among students for publishing the first scientific evidence to support the "Colbert bump." His new book, co-written with sociologist Nicholas Christakis, is Connected: The Surprising Power of Social Networks and How They Shape Our Lives,

Review by Luc Reid

In their book Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives, sociologist Nicholas Christakis and political scientist James Fowler look at what it means to be a human being in terms of our interpersonal networks. One of the topics they take up is an examination of how selfishness, cooperation, and altruism interact, which helps answer the question in the title: can we expect others to help us?

Christakis and Fowler take results from experiments around the world with three games. In the “Ultimatum Game,” two people are given an amount of money (for instance, ten dollars).

Person 1 makes an offer to split it with the other, offering anything from a penny to a 50/50 split to handing over the whole amount. Person 2 decides to reject or accept the offer. If Person 2 rejects the offer, neither person gets anything.

The “Dictator Game” is similar, except that any offer is automatically accepted. All the power lies with Person 1.

In the “Trust Game,” Person 1 can give any amount to Person 2, and that amount triples, at which point Person 2 can give any amount back. If both cooperate completely, they each get more than the original amount. If they don’t, someone gets screwed.

I won’t go into the experimental findings in detail, but instead will head straight for the conclusions Christakis, Fowler, and others draw from the results.

Based on the mixture of selfishness, cooperation, trust, mistrust, and other attitudes demonstrated by subjects in these experiments, they identify three types of people: cooperators, loners, and free riders.

Cooperators tend to trust more, are more helpful to others, and are dependent on other people trusting and helping in return. Loners tend not to trust and try not to depend on anyone else. Free riders take advantage of cooperators to get whatever they can for themselves without offering anything in return.

A cooperator in the midst of other cooperators thrives. A cooperator who runs into too many free riders gets screwed. A loner is less successful than others if everyone else is successfully cooperating, but isn’t in danger of being taken advantage of by free riders. A free rider thrives when cooperators let things go, but runs into trouble with a sort of cooperator sub-type that Christakis and Fowler dub “Punishers.” Punishers are willing to exert some effort to penalize people for not cooperating or for taking advantage of the system.

In the ultimatum or dictator game, a cooperator might offer half or close to half of the money to the other person. A loner in the trust game will assume the other person is going to take advantage and act defensively. A free rider will take the most money available regardless of consequences to the other player. A punisher in the ultimatum game will refuse an offer that seems too low even though this would mean both players lose out.

What’s fascinating to me is that according to Christakis and Fowler, a society is made up of all of these types, but the proportions of each are constantly shifting. There appear to be times and places where cooperators spread, which might eventually attract free riders, which in turn will attract punishers and perhaps turn some of the cooperators into loners. If loners are everywhere, then some might band together and be more successful by cooperation, starting the cycle over. During each separate phase of this cycle, which might last for some time, there are different opportunities and dangers, and the question of whether help is likely to be available is answered differently.

So when looking for help in our lives, there are questions we can ask ourselves. Are we given to cooperation, or do we tend to do things on our own? What about the people around us? And whether or not a person tends to help in one area suggests a lot about whether that person is likely to help in another.

For instance, a person who gives money to public radio is also more likely to volunteer to help you move or to give you directions if you’re lost. A person who works in a kind of job that emphasizes getting as much as you can, like a stockbroker or auto salesperson, is less likely to trust and offer help to others – though of course it’s inaccurate to make blanket statements about people on this matter; these are just general observations that are often true.

Regardless, making these kinds of observations about yourself and the people you’re connected with can help provide insight both about what you’re contributing and what you can expect from others.