3 July 2010 | NewScientist | 9

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After the World Cup

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EXTROVERTS are born not made – or at least, that’s what they say. But what if it’s more subtle than that? What if we tailor our personalities to our surroundings to make the most of our genes?

Conventional comparisons between identical and fraternal twins indicate that nearly half of individual differences in personality traits have some underlying genetic cause. So people have tended to think of personality traits as largely determined by genes, says evolutionary psychologist Aaron Lukaszewski of the University of California at Santa Barbara.

He felt there was a flaw in this thinking: if personality were rigidly determined, individuals could end up with the “wrong” personality type for their circumstances. Being extrovert, for instance, exposes people to social conflict. Wimpy men are more likely to suffer in such encounters, while hunkier men may benefit from putting good genes on display. To avoid mismatches, Lukaszewski reasoned, evolution must have favoured a more flexible system.

To test this idea, he measured the strength of 85 male and 89 female students and asked them to rate their own attractiveness relative to their peers. Then he gave each a standard personality test to measure how extrovert they were. Sure enough, stronger and more attractive men, and more attractive women, were more extrovert, Lukaszewski reported at a June meeting of the Human Behavior and Evolution Society in Eugene, Oregon.

Independent ratings of attractiveness showed extroverts didn’t simply tend to rate themselves more highly. In fact, physical strength and how people rated themselves explained a whopping 30 per cent of the

variation in extroversion between the volunteers – a huge effect for something as nebulous as personality. “That’s surprisingly high to me,” says Robert Plomin of the Institute of Psychiatry in London. “That makes it much more interesting.”

And because strength and attractiveness themselves have a strong genetic basis, it appears that most of the “genetic” basis of personality may actually be a response to these other genes. In other words, we may learn our personalities, and adjust them to situations we find ourselves in over time. “It’s not the way psychologists have typically thought about personality,” says Wendy Johnson, a psychologist at the University of Edinburgh, UK. “But it is the way they should be thinking of it.”

The next step could be to experimentally modify an individual’s assessment of their strength or attractiveness – by surrounding them with unusually strong or attractive individuals,

for example – to see if this affects their extroversion score.

Meanwhile, evidence from a different quarter suggests that Lukaszewski might be onto something. Studies of individuals in immersive online “worlds” such as World of Warcraft show that their personas within the game become more gregarious when they are given subtly more attractive computer selves, or avatars, says Nick Yee of the Palo Alto Research Center in California. Indeed, the effect carried over into the real world for at least a few minutes, Yee says. Bob Holmes, Eugene, Oregon n

If you’ve got great genes, it pays to be extrovert

“We learn our personalities over time and adjust traits to the situations we find ourselves in”

–Showy genes –

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