““aggressivity common in hunter-gatherer groups. The human fossil record shows that in the period prior to settlement, there had been a gradual thinning of the human skeleton, a process known to physical anthropologists as gracilization. Gracilization typically occurs in the skeletons of wild animal species as they become domesticated. It seems that humans underwent a similar lightening of their bone structure for the same reason—that they were becoming less aggressive. Like animals undergoing domestication, humans shed bone mass because extreme aggressivity no longer carried the same survival advantages,””
