Both men and women look for altruism when choosing a mate, and women place significantly more importance on altruistic traits—represented by things like donating blood or volunteering in a hospital—than on anything else, according to a new study from a group of biologists and psychologists at The University of Nottingham in England.
“For many years the standard explanation for altruistic behavior toward nonrelatives has been based on reciprocity and reputation—a version of ‘you scratch my back and I’ll scratch yours,'" says biologist Tim Phillips, who led the study that appears in the British Journal of Psychology (and which seems to be based on his doctoral thesis). "I believe we need to look elsewhere to understand the roots of human altruism. The expansion of the human brain would have greatly increased the cost of raising children so it would have been important for our ancestors to choose mates both willing and able to be good, long-term parents. Displays of altruism could well have provided accurate clues to this and genes linked to altruism would have been favored as a result.”
In other words, the hypothesis is that human altruism evolved as a result of sexual selection. “Sexual selection," concludes Phillips, "could well come to be seen as exerting a major influence on what made humans human.” —Heather Wax