Chimps sensitive to what is right and wrong: study

Chimps, like humans, are sensitive to what is right and wrong but will only react if someone is trying to harm a member of their own group, according to a new study.
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, researchers said.
The research provides the first evidence that chimpanzees, like humans, are sensitive to the appropriateness of behaviours, especially those directed towards infants.
It also shows that these primates might only take action when a member of their own group is being harmed.

The researchers filmed two social groups of chimpanzees living in two Swiss zoological gardens while the animals repeatedly viewed film clips.
The films portrayed the actions of other chimps unknown to them. The control clip showed chimps doing neutral activities such as walking or cracking nuts.

The experimental clips included aggressive scenes, such as an infant chimpanzee being killed by its own kind, a small colobus monkey being hunted and killed by chimps, and socially aggressive behaviour between chimpanzee adults.
The taped sessions were analysed to find out how long the chimps in the experiment looked at the screen, whether they were aroused or affected by what they saw, and how they behaved while doing so.

The zoo animals looked up to four times longer at the infanticide scenes than at any of the other films. The chimps did not merely respond to the infant screams they heard, they paid preferential attention to these scenes as a whole.
This shows that chimpanzees can distinguish severe aggression against infants from other forms of aggression and harmful behaviour.
It also indicates that such incidents do not match the social expectations of tolerance normally granted towards infants.
This is a form of so-called proto social norms at work, where individuals react as bystanders to a violation of a certain expectation of how others should behave.

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," said Claudia Rudolf von Rohr from the University of Zurich in Switzerland, lead author of the research paper published in the journal Human Nature.