Leave it to the Brits to reduce acts of public goods by men to nothing more than competition for females. "That's blasphemy!" you say, "those redcoat reductionists aren't going to tell me that Gandhi was just trying to get laid!" But American revolutionary slurs for Brits aside ("lobsterback" is a personal favorite), a new paper in the British Journal of Psychology experimentally tests the idea that men do good deeds to show off and gain favor with potential mates.
The researchers, Wendy Iredale and Mark Van Vugt of Sheffield and Oxford University, had a bunch of young men and woman partake in a "public goods game" – essentially a computer game that involved donating real money to a group fund with the loose promise that you, and the invisible strangers sharing the fund, would make more money if each member donated more than they kept.
Iredale and Vugt stuck an "observer" in the experiment, who would closely watch individual subjects play the game. By mixing up the sex of the observer, they were able to collect data that compared how subjects were differentially affected by being watched by a man or woman . They found that the only scenario that significantly increased public donations was when the subject was a man and the observer was a female.
According to the pair, they found “that men contributed more in the presence of an opposite sex audience, but there was no parallel effect for women. In addition, men's public good contributions went up as they rated the female observer more attractive….Theoretically, this suggests that a public good is the human equivalent of the peacock's tail.”
What does being generous in front of a mate have to do with fat bird feathers? The authors argue that altruism is attractive, because, like a fancy peacock's tail, it is costly to the holder of the trait and thus demands some decent genetic stock:
This hypothesis is derived from an integration of two well-established evolutionary theories; costly signaling and sexual selection theory. Costly signaling theory suggests that certain traits evolve because they convey honest information about the underlying qualities of an individual, and the costlier the trait the more reliable the signal. For instance, the conspicuous peacock's tail signals to peahens that this male is healthy and genetically fit. Since public generosity is costly to the self, it may therefore signal important information to others, including potential mates, about an individual's quality.
Ok, that is believable enough, but why did the results show this effect in men but not women?
Sexual selection theory generally argues that women are choosier mate-selectors than men, mostly because they have to bear children and the repercussions of a bad mate choice are potentially devastating. While Iredale and Vugt rightly do not believe that either sex is more altruistic than the other, they argue that female "choosiness" may force men to broadcast their altruism more publicly in order to compete for female attention, an idea which their data seems to support.
Sure, it’s a fairly basic study, and it doesn’t describe any of the other important evolutionary benefits of altruism that aren't specific to any gender. But the results do betray a sordid probable truth about male do-gooders – perhaps all these door-holding, greenpeacing, public-speaking nice guys are merely flashing their colorful man-tails.