According to a new study published Wednesday, September 17th in Nature, chimpanzees kill by nature to gain advantage. The study involved a a review of all known cases when chimpanzees or bonobos in Africa killed members of their own species, and the results showed that violence was not related to actions by humans that might cause chimp aggression or lethal attacks.
The researchers say their analysis supports the idea that warlike violence in chimps is a “natural behavior” that has evolved naturally because it provides more resources or territory to the killers for a minimal risk.
Statement from study co-author
Dr. Michael L. Wilson, an anthropologist at the University of Minnesota and a co-author and organizer of the study, highlighted the complexity of the issues behind the research. “We’re trying to make inferences about human evolution.”
Wilson and the other authors, who contributed data on chimp killings from groups they studied, say there is no apparent relationship between human impact on the chimp sites and the number of killings.
Wilson also noted that the Ngogo group of chimpanzees in Uganda “turned out to be the most violent group of chimpanzees there is,” even though the area was minimally disturbed by humans.
The chimps have a pristine natural habitat, he said, yet “they go around and kill their neighbors.”
Other anthropologists skeptical on Chimpanzees
Other experts were skeptical about the research. Robert Sussman, an anthropologist at Washington University who has argued human impacts put pressure on chimp societies that result in killings, was critical of the new study. “It doesn’t establish anything, really,” he said.
“The statistics don’t tell me anything,” Sussman commented. Two sites provided most of the data, he noted, while the other 20 chimp communities had very few killings. He pointed out the paper also conflated killings that were observed, inferred and suspected. Moreover, he said, “They haven’t established lack of human interference.”
Dr. Brian Ferguson, an anthropologist at Rutgers University an expert on human warfare who is working on a book about chimpanzee and human violence, also agreed that the measures of human impact were questionable. The new study looked at whether chimps were fed by people, the extent of their range and the disturbance of the habitat. However, as Ferguson noted, impact “can’t be assessed by simple factors.”