Chimpanzees have been well-known to orchestrate co-ordinated attacks on members of their own species. It has been thought, however, that this commonly observed lethal chimp-on-chimp aggression was due to human disturbance. a 50 year study has indicated that this is not the case. 18 different chimpanzee communities were studied, in areas experiencing varying amounts of human influence. 152 chimp killings were analyzed. It turns out that the majority of attackers and victims were male, and that there was no correlation between how much human impact a community experienced and how much violence occurred. This information is consistent with the theory that chimp violence is primarily driven by adaptive fitness benefits. Since chimpanzees are about 95% genetically identical to us, they can be used as a model to study human nature and violence.