Study co-author and organizer Michael L. Wilson from the University of Minnesota told Discovery most killings were gang attacks and males were the most frequent attackers and victims.
But other scientists say the study's results aren't conclusive, with many questioning how the information was collected. One anthropologist from Washington University in St. Louis told Science, "I am surprised that [the study] was accepted for publication."
Aside from the evolution-vs.-human-interference debate, there's also disagreement on what implications this study has about human behavior.
Wilson told the Los Angeles Times chimp violence suggests warfare has "a long evolutionary history."
But a writer for Nature not associated with the study commented, "Humans are not destined to be warlike because chimpanzees sometimes kill their neighbours."
Wilson and his study's critics both agree you can't jump to conclusions about why humans fight based just on these findings.
This video includes a images from Daniel / CC BY NC 2.0 and Getty Images.