Researchers from Spain have found that a tendency to bump off members of the same species is particularly common among primates, and have estimated that around 2% of human deaths at the origin of our species were down to such lethal spats.

“What it is saying, in the broadest terms, is that humans have evolved strategies for solving problems with violence,” said Mark Pagel, professor of evolutionary biology at the University of Reading, who was not involved in the research. ...