A new study says that humans aren’t the cause of chimpanzee aggression.

Humans as the source of chimpanzee aggression was believed for some years, and it was said that humans who lived among chimpanzees in places such as Africa were “provocation” for animals who simply wanted to live at peace among themselves. The latest study examined 18 chimpanzee communities over 50 years as well as 152 chimpanzee killings. Even in situations where no humans were present, some chimpanzees still asserted aggression and killed other members of the same animal species.

Thirty researchers took part in the study, including Fisher Center for the Study and Conservation of Apes research fellow David Morgan and his wife Crickette Sanz. Morgan says that there’s always been some connection between ape aggression and human aggression but that the conflict between apes and humans has always kept the connection from being explored further. “The similarities between chimpanzee intergroup aggression and human warfare has received a great deal of attention. Until now, the ‘chimpanzee model’ of aggression was called into question because detractors suggested the violence observed in chimpanzees was a product of human disturbance rather than adaptive strategy. Based on our findings this isn’t the case,” Morgan said.

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Morgan also notes that the study, while showing spontaneous aggression amongst chimpanzees, as is the case with humans, also shows that humans are different from chimpanzees and that we need to respect the differences. It is true that chimpanzees may very well become aggressive for reasons that defy understanding, but, unlike humans, don’t possess the intellectual power and ability to stop themselves when turning aggressive. Humans, on the other hand, can prevent themselves from doing something terrible and can see their aggression in time to make a decision to refrain from a given action.

The study was published Wednesday in the Nature journal.