HENRY

A new paper in P.N.A.S. shows that co-operation in chimpanzees is not limited to kin groups. National Geographic says:

By combining field observations with DNA analysis of fecal samples, his team found that male chimps prefer to work with their brothers by the same mother. The chimps often teamed up with these siblings to perform one of six observed behaviors, such as grooming fur or forming a two-chimp alliance to beat up a third individual.

But the scientists also discovered that male chimps frequently cooperate with unrelated or distantly related males in their community to perform tasks such as group hunts for red colobus monkeys or patrolling territory boundaries for intruders.

The abstract of Langergraber et al says

The complex cooperative behavior exhibited by wild chimpanzees generates considerable theoretical and empirical interest, yet we know very little about the mechanisms responsible for its evolution. Here, we investigate the influence of kinship on the cooperative behavior of male chimpanzees living in an unusually large community at Ngogo in Kibale National Park, Uganda. Using long-term field observations and molecular genetic techniques to identify kin relations between individuals, we show that male chimpanzees clearly prefer to affiliate and cooperate with their maternal brothers in several behavioral contexts. Despite these results, additional analyses reveal that the impact of kinship is limited; paternal brothers do not selectively affiliate and cooperate, probably because they cannot be reliably recognized, and the majority of highly affiliative and cooperative dyads are actually unrelated or distantly related. These findings add to a growing body of research that indicates that animals cooperate with each other to obtain both direct and indirect fitness benefits and that complex cooperation can occur between kin and nonkin alike.

Posted on April 27th, 2007 by Simon Greenhill