Humans get some of their knack for killing each other from the primate family tree, a new study says [View all]

but that doesn’t let us off the hook.....

"The first humans were about as violent as could be expected based on their family tree, researchers report September 28 in the journal Nature. The scientists pored through examples of lethal violence—not animals killing other species, such as predators and prey, but killings within a species, whether by cannibalism, infanticide, or aggression."

"Lethal violence increased over the course of mammal evolution. While only about 0.3 percent of all mammals die in conflict with members of their own species, that rate is sixfold higher, or about 2 percent, for primates. Early humans likewise should have about a 2 percent rate—and that lines up with evidence of violence in Paleolithic human remains."

"The medieval period was a particular killer, with human-on-human violence responsible for 12 percent of recorded deaths. But for the last century, we’ve been relatively peaceable, killing one another off at a rate of just 1.33 percent worldwide. And in the least violent parts of the world today, we enjoy homicide rates as low as 0.01 percent."

https://www.nationalgeographic.com/news/2016/09/human-violence-evolution-animals-nature-science/