A survey of British skulls from the early part of the New Stone Age, or Neolithic, shows societies then were more violent than was supposed.
Early Neolithic Britons had a one in 20 chance of suffering a skull fracture at the hands of someone else and a one in 50 chance of dying from their injuries.
Details were presented at a meeting of the Society for American Archaeology and reported in New Scientist magazine.
Still reading Leblanc's Constant Battles so this jumped out. It doesn't really seem surprising in that light.