How a chimpanzee views a video of an infant chimp from another group being killed gives a sense of how human morality and social norms might have evolved. So says Claudia Rudolf von Rohr of the University of Zurich in Switzerland, lead author of a paper in Springer’s journal Human Nature. It provides the first evidence that chimpanzees, like humans, are sensitive to the appropriateness of behaviors, especially those directed toward infants. It also shows that these primates might only take action when a member of their own group is being harmed.
Interestingly, although the chimps viewed the infanticide scenes much longer, the research team found only limited evidence that what they saw caused the viewing chimps to be more aroused or to react to them.
“The results suggest that chimpanzees detect norm violations both within their group as well as in a group of unfamiliar individuals, but that they will only respond emotionally to such norm violations within their own group,” says Rudolf von Rohr.