By Paul Rincon
BBC News science reporter
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.
Women were sometimes the victims of violence (Image: Rick Schulting)
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.
Blunt instruments such as clubs were responsible for most of the traumas.
This is not the first time human-induced injuries have been identified in Neolithic people; but the authors say it is the first study to give some idea of the overall frequency of such traumas.
Rick Schulting of Queen's University Belfast and Michael Wysocki from the University of Central Lancashire looked at 350 skulls spanning the period from 4000 BC to 3200 BC.
"We generally think of Neolithic people as living peaceful lives - they were busy looking after cereal crops and rearing livestock," Mr Wysocki told the BBC News website.
"But it was a much more violent society."
Nearly 5% of the skulls showed healed depressed fractures. They found unhealed injuries in 2% of the sample, suggesting these individuals died from their wounds.
But the true scale of the violence still remains unclear due to the nature of the evidence, say the authors. In other simple, small-scale societies, the incidence of death as a result of violence ranges from 8-33%.
"Our data shows 2% lethal cranial injuries, but these are just cranial. The data for other societies is for all lethal injuries, but ours is limited so we can't compare it," Mr Wysocki said.
Some injuries were caused by projectiles (Image: Rick Schulting)
"A lot of lethal injuries will be to soft tissues and that needn't affect bone."
The researchers suspect that what they are seeing is violence at the local and regional level rather than large-scale warfare involving large sections of the country.
"We could also be seeing raiding parties, cattle rustling, somebody suspecting the other tribe across the hill is practising witchcraft," the University of Central Lancashire forensic anthropologist explained.
"Some of the violence may be domestic; some of it may even be ritualised."
The majority of the traumas were caused by blunt instruments which may have included improvised clubs. But a handful of fractures look like they have been inflicted by flint arrowheads and spearpoints. One of the females in the sample appears to have been the victim of a brutal attack with a stone axe.
Another individual with a suspected projectile fracture appears to have had their ears slashed off - a possible instance of trophy-taking, the researchers speculate.
The research originally appeared in the Proceedings of the Prehistoric Society journal.