Altruisim is a puzzle for Darwinian evolution. How could we have evolved to be selfless when it is clearly a costly business? Many experimental games between volunteers who have to decide how much to donate to other players have shown that people do not behave in their immediate self-interest. We are more generous than necessary and are prepared to punish someone who offers an unfair deal, even if it costs us (New Scientist, 12 March, p 33).

To some, this is evidence of "strong reciprocity", which they believe evolved in our prehistoric ancestors because kind groups did better than groups of selfish individuals. But others argue that altruism is an illusion. "It looks like the people in the experiments are trying to be nice, but the niceness is a mirage," says Terry Burnham at Harvard University.

He and Brian Hare pitted 96 volunteers against each other anonymously in games where they donate money or withhold it. Donating into a communal pot would yield the most money, but only if others donated too.

The researchers split the group into two. Half made their choices undisturbed at a computer screen, while the others were faced with a photo of Kismet- ostensibly not part of the experiment. The players who gazed at the cute robot gave 30 per cent more to the pot than the others. Burnham and Hare believe that at some subconscious level they were aware of being watched. Being seen to be generous might mean an increased chance of receiving gifts in future or less chance of punishment, they will report in Human Nature.

Burnham believes that even though the parts of our brain that carry out decision-making know that the robot image is just that, Kismet's eyes trigger something more deep-seated.
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16-Mar-2005