11.4 Reciprocal Altruism

Natural selection for mutualism adds up to groups of cooperative individuals, reaping the benefits of sharing, social support, and exchange. Though this may start with the exchange of food and grooming, over time it builds to much larger favors and support. For example, alloparenting and cooperative breeding likely evolved as cooperators supported nursing mothers who may not have been able to forage or hunt for their own calories while tied to hungry young. Yet look at what humans have accomplished as the result of sharing and community.

In truth, altruism is the culmination of mutualism, cooperation, and a tolerance for delayed reciprocity. By definition, reciprocal altruism occurs when an individual temporarily reduces their own fitness or reproductive opportunities while increasing the fitness of others. Yet, unlike the idealistic definition of altruism, reciprocal altruism acknowledges that, at some point, the individual will rely on the receiver to do the same.

This is how cooperation builds. Those who invest in others and build social trust can be confident that the group will take care of them when it is time. In many ways, this is more beautiful than plain old altruism. Rather than fawning over displays of selflessness, we can instead enjoy the beauty of cooperation and shared care.

At the end of it all, altruism can only evolve if the altruistic act is reciprocated.

And that, is mutualism.