Altruism is traditionally defined as: “behavior by an animal that is not beneficial to or may be harmful to itself but that benefits others of its species.” So here’s a simple question: why would anyone be altruistic?
One answer has to do with our relatives. Sociobiology suggests that all living creatures share one fundamental goal: to propagate our genes into future generations. Of course, the most direct way to propagate our genes is to reproduce.
But we can also propagate our genes by supporting our genetic relatives. So I might behave altruistically toward my sister because she shares much of my genome. If she reproduces successfully (and her children do as well), then some of my genetic heritage is passed on to future generations. So it pays to be nice to my sister. (It took me a long time to figure this out).
But why would anyone be altruistic toward someone who is not a genetic relative? According to Steven Arnocky’s recent paper in the British Journal of Psychology it has to do with another fundamental human drive: sex.
You may recall that competition for sex is a key element in maintaining the overall health of a species. When there is a fair amount of competition among males, females are remarkably good at picking out the best mates. What does “best” mean in this sense? The best men for producing healthy offspring who can in turn produce healthy offspring of their own.
So how do females know which males will produce the best offspring? Some of it is physical. For instance, females strongly prefer males who are symmetric rather than asymmetric. Being symmetric is, apparently, a good marker of genetic health.
Behavior also plays a role. We know, for instance, that creativity plays a strong role in mate selection – for both men and women. Ornamental creativity is especially attractive. Strictly speaking, ornamental creativity is not essential to survival. So those who display this trait are effectively advertising “I have more than enough to survive plus some left over for ornamentation. I have an abundance of what you want.”
According to Arnocky’s paper, non-kin altruism plays a similar role to creativity. It’s a behavior that is desirable to the opposite sex. The study used two different methods to measure altruism and then correlated the degree of altruism with sexual activity. Those who scored higher on altruism, “…reported having more sex partners, more casual sex partners, and having sex more often within relationships.” The correlation was stronger for men than women, suggesting that altruism is more important for women selecting men than for men selecting women.
In an interview, Arnocky summed up the results by noting that, “”It appears that altruism evolved in our species, in part, because it serves as a signal of other underlying desirable qualities, which helps individuals reproduce.”
Based on Arnocky’s findings, we may have been defining altruism improperly. The classic definition says that altruism doesn’t benefit the individual but does benefit the species. But Arnocky’s paper points out a very direct benefit to the individual – better mates and more of them. Given this, we need to re-phrase our initial question. It probably should be: why wouldn’t everyone be altruistic?
(Less technical summaries of Arnocky’s paper are here and here).