While researchers have long debated whether violence among chimpanzees is a form of social posturing or a response to human activities, a new study argues aggression is actually part of the primates' nature.

Since primatologist Jane Goodall in the 1970s reported violence among the chimpanzees she was studying in the wild, it's been generally believed such behaviors are similar to primitive human warfare, adaptive approaches intended to give perpetrators an edge -- or outbursts brought about by humans who fed the creatures or destroyed their natural habitats.

But, the latest findings out of the University of Minnesota that incorporates data from all long-term chimpanzee study sites in Africa have found human activity isn't to blame for the hurtful behaviors.

The new research is highlighted in a paper published online in the scientific journal Nature.

"Chimps and bonobos are the two living species most closely related to us of all the animals alive today; we share the most in common in terms of genetics and evolutionary history," lead researcher Michael L. Wilson said in a university press release. "Based on our results, it's clear that lethal aggression is something that chimpanzees naturally do. We found that chimpanzees sometimes kill other chimpanzees, regardless of whether human impacts are high or low, whereas bonobos were not observed to kill, whatever the level of human impacts."

Wilson, an associate professor in the University of Minnesota's College of Liberal Arts' anthropology department who holds a joint appointment in the College of Biological Sciences, collaborated with 29 colleagues at sites throughout Africa to obtain the necessary data for the study, which compiled over five decades of information from 18 chimpanzee (Pan troglodytes) communities and four bonobo (Pan paniscus) communities.

"People have long been interested in chimps as a way to better understand the evolution of human behavior," Wilson said, and while the new findings answer one question, many remain.

"It's still an open question whether this sort of violence is something that has happened continuously in human evolutionary history, or whether it arose independently in humans and chimps," he said. "Perhaps our common ancestor, which we believe lived 5 to 7 million years ago, also had high rates of violence, too."

The study grew from a growing number of opinions in the media claiming that chimpanzee violence has been caused by human activity.

"This is an important question to get right. If we are using chimpanzees as a model for understanding human violence, we need to know what really causes chimpanzees to be violent. And for the sake of chimpanzee conservation, if human activities are causing chimpanzees to kill each other, we need to address that."

Wilson was a consultant on the 2014 film "Dawn of the Planet of the Apes," providing recordings of chimpanzees for use in the sound design.