Murder in our genes
A chilling prehistoric war grave, holding the smashed remains of hunter-gatherers, provides the first evidence of a human massacre and demonstrates the terrifying aggression of early man.
The fossilised bones of 27 people, murdered 10000 years ago, have been discovered at Nataruk, near Lake Turkana, in Kenya.
Four victims, including a heavily pregnant woman, were bound by the hands and feet before being slaughtered. The others showed signs of extreme violence.
The origins of human aggression are controversial, with many archaeologists believing that hunter-gatherers were largely peaceful - and did not resort to warfare until after the agricultural revolution. That is when groups grew jealous of the land and possessions of their rivals. Before the find, the earliest war grave was at Darmstadt, in Germany, dated at around 5000BC.
But the Nataruk massacre is the earliest scientifically dated historical evidence of human conflict. Study author Professor Robert Foley, of Cambridge's Leverhulme Centre for Human Evolutionary Studies, said the findings showed violence was as much part of the human character as the altruism that allowed us to be the most co-operative species.
He said: "I've no doubt it is in our biology to be aggressive and lethal, just as it is to be deeply caring and loving. A lot of what we understand about human evolutionary biology suggests these are two sides of the same coin."
The 27 skeletons included at least eight women and six children. Twelve of the skeletons were relatively complete and showed clear signs of a violent death, including smashed skulls and cheekbones, broken hands, ribs and knees, and evidence of arrow wounds in the neck. Arrows were lodged in the skull and chest of two men.
Several skeletons were found face down with smashed faces, possibly having been clubbed. None had been buried.
Lead author of the report on the find Marta Mirazón Lahr said: "These remains record the intentional killing of a small band of foragers and provide unique evidence that warfare was part of the repertoire of inter-group relations among some prehistoric hunter-gatherers."
Archaeologists believe the victims represent an extended family that was attacked and killed by a rival group at around the start of the Holocene: the geological epoch that followed the last Ice Age.
The research was published in the journal Nature.