A study published in the scientific journal Nature concludes that chimpanzees kill each other to eliminate rivals and gain better access to territory, mates, food or other resources.

“Observations that chimpanzees kill members of their own species have influenced efforts to understand the evolution of human violence,” said University of Michigan anthropologist John Mitani.

Mitani worked on the international analysis with 30 colleagues worldwide, looking at lethal aggression among 18 chimpanzee communities in Africa over five decades.

Mitani – who has been studying chimpanzees in Uganda’s Kibale National Park for two decades – said the research provides strong support that killing is an evolved tactic.

According to Mitani, there is nothing in the findings that suggest that the human propensity to kill others is hard-wired and unavoidable.

"There is considerable variation in rates of killing by chimpanzees living in different populations, so even in chimpanzees killing is not inevitable," he said. "And, of course, we are humans and not chimpanzees. We have the ability to shape and alter our behavior in ways that they can't. We can alleviate considerable human suffering by harnessing that ability."

The study provides evidence to counter the argument that such killing doesn't come naturally but is instead worsened by human activities such as deforestation or feeding chimps that are being studied.

"Humans have long impacted African tropical forests and chimpanzees, and one of the long-standing questions is if human disturbance is an underlying factor causing the lethal aggression observed," explained co-author David Morgan, PhD, research fellow with the Lester E Fisher Center for the Study and Conservation of Apes at Lincoln Park Zoo in Chicago. Morgan has studied chimpanzees deep in the forests of Republic of Congo for 14 years.

"A key take-away from this research is that human influence does not spur increased aggression within or between chimpanzee communities."

The study found that the majority of violent attackers were male and males who were males acting in groups.

Mitani said violence had little to do with human impact, but that the incidents did increase when there was a high population and a large number of males who banded together.

"The more we learn about chimpanzee aggression and factors that trigger lethal attacks among chimpanzees, the more prepared park managers and government officials will be in addressing and mitigating risks to populations particularly with changing land use by humans in chimpanzee habitat," Morgan added.