Chimpanzees and humans share much in common, including cooperating to kill perceived rivals, and now a new study finds that this kind of lethal aggression -- at least among chimps -- is "normal" and sadly all too common.
"Normal," in this case, means that the behavior results from natural and evolved tendencies and does not, as some other researchers have suggested, emerge in response to human pressures, such as habitat loss.
The study, published in the journal Nature, sheds light on the evolutionary roots of lethal conflict among certain primates, including humans. An accompanying "News & Views" article in the same journal, for example, points out that in 2013 alone, there were 33 armed state-level conflicts around the world. Many of them have persisted for decades.
Chimps are just as violent.
"Most killings involve gang attacks," Michael Wilson, who led the new study, told Discovery News. "When attacking adults, many attackers pile onto the victim. They pin the victim to the ground and hit, kick and bite the victim."