Altruism Gene May Limit Individual Reproduction, Increase Overall Group Fitness

Human cultural practices requiring language and sophisticated cognitive skills may propagate altruistic behavior, according to two articles in the 8 December issue of Science.

Samuel Bowles, professor and director of the Behavioral Sciences Program at the Santa Fe Institute in Santa Fe, New Mexico, assembled genetic, climactic, archeological, ethnographic, and experimental data to examine human cooperation in an economics-based cost-benefit model. Specifically, he looked at the ecological challenges facing humans during the late Pleistocene and early Holocene (about 150,000 to 10,000 years ago) that resulted in intense competition for resources, frequent group extinctions, and inter-group violence.

In his model, members of a group bearing genes for altruistic behavior pay a tax by limiting their reproductive opportunities to benefit from sharing food and information, thereby increasing the average fitness of the group as well as their inter-relatedness. Bands of altruistic humans would then act together to gain resources from other groups at this challenging time in history. Examples of altruistic tasks include sharing food beyond immediate family, consensus decision-making, and monogamy, the authors say.

In a related Review, Martin A. Nowak, director of the Program for Evolutionary Dynamics at Harvard University, describe mechanisms for the evolution of cooperation in other units including genomes, cells, multicellular organisms, social insects, and human society. He explained these biological entities depend on cooperation to obtain greater levels of organization by relinquishing selfish replicators and some reproductive potential to help one another.

Benjamin Somers and Evelyn Brown

8 December 2006