Chimp violence not linked to human influence

Chimpanzee violence is a result of adaptive strategy that gives the perpetrators an edge and not due to human disturbance, says a study that looked into patterns of inter-group aggression in chimpanzees and their close relatives, bonobos.

"This study debunks the idea that lethal aggression among wild chimpanzees is an aberrant behaviour caused by human disturbances, like artificial feeding or habitat loss," said study co-author Ian Gilby from the Arizona State University in the US.

In the 1970s, reports of chimpanzee violence caught the attention of a global audience.

Since then, many people have compared chimpanzee inter-group aggression to primitive warfare and have argued that chimpanzee violence is an adaptive strategy that gives the perpetrators an edge.

Others have argued that lethal aggression is the consequence of human activities such as provisioning (artificial feeding) by researchers or habitat destruction.

For the current study, the researchers compiled data collected over five decades from 18 chimpanzee (Pan troglodytes) and four bonobo (Pan paniscus) communities.

Lethal aggression directed toward members of other groups is part of the natural behavioural repertoire of chimpanzees - sometimes chimpanzees kill each other, regardless of human impact, the findings showed.

The study appeared in the journal Nature.