Phylogenetic roots of human lethal violence

The philosopher Thomas Hobbes said that people are inherently violent; Jean-Jacques Rousseau, that people are usually peaceable. The reality presumably lies somewhere in between, but where? Here José María Gomez et al. present a phylogenetic analysis of intraspecies lethal violence in more than 1,000 mammalian species. They show that whereas lethal violence is almost unknown in some clades, such as bats and whales, it is a particular feature of primates. The level of lethal violence during human prehistory inferred from empirical observations is in line with the phylogenetic prediction, but during most historic periods was higher than the phylogenetic predictions. In modern times, cultural practices appear to have modulated the tendency towards violence that nature has given us.