PNAS has just published a paper on Spontaneous Prosocial Chooice by Chimpanzees. It is a little off topic for this blog but the role of cooperation in the evolutiion of language is so central to this blog that I want to bring my readers' attention to anything that challengnes the thesis. Although, really it does noto challenge the position that sharing knowledge is basic to humans, rare amongst chimps.
The paper describes experiments in which the chimpanzees prefer behavior that gives themselves and a fellow chimpanzee a reward over behavior in which the actor alone receives an award. This shows a sympathy and "common decency" that has sometimes been denied. But it doesn't really address the issue of cooperation in which two or more individuals work together toward a common goal, at some risk or cost to the participants. The behavior show here carries no cost.. Still, it is not nothing.