Skull of a male skeleton found lying prone in the lagoon’s sediments. The skull has multiple lesions on the front and on the left side, consistent with wounds from a blunt implement, such as a club.

Evidence for the brutal massacre of a hunter-gatherer group is shattering long-held beliefs that pre-farming societies were essentially peaceful. The remains of more than 27 individuals uncovered at Nataruk, 30km west of Lake Turkana in Kenya, include at least eight women – one in the final stages of pregnancy – and six young children.

Radiocarbon dates from shells directly associated with the human remains, optical luminescence dates on the sediments, and uranium-series dating of the bones themselves, suggest the group lived about 9,500-10,500 years ago. Ten of 12 near-complete skeletons showed evidence of violent death: some had suffered blunt-force trauma to the head and face; five, possibly six, were killed by projectile points, probably arrows – two microliths were discovered within the pelvic area and chest of one male skeleton, and an obsidian bladelet was still embedded in the skull of another. Several had broken bones and fractures to hands and knees, and it appears some also had their hands and even feet bound before they were killed.

Evidence of inter-group violence in prehistoric hunter-gatherers is rare. Remains from the early Holocene site Jebel Sahaba in Sudan include individuals who died violently, but they were buried in a cemetery, suggesting at least some degree of sedentism. At Nataruk, however, the dead were left just where they fell. This suggests they were deliberately killed by a rival group, perhaps in a dispute over territory, resources, or kinship. However, the team from Cambridge University’s Leverhulme Centre for Human Evolutionary Studies explains that while such conflicts were thought to typically arise when supplies were scarce, archaeobotanical and archaeozoological evidence shows that 10,000 years ago Nataruk was a fertile lakeshore with abundant flora and fauna to support such hunter-gatherer communities.

‘These human remains record the intentional killing of a small band of foragers with no deliberate burial, and provide unique evidence that warfare was part of the repertoire of inter-group relations among some prehistoric hunter-gatherers,’ said Dr Marta Mirazon Lahr, director of the In-Africa Project that discovered the site in 2012, adding: ‘The massacre may have resulted from an attempt to seize resources – territory, women, children, food stored in pots – whose value was similar to those of later food-producing agricultural societies, among whom violent attacks on settlements became part of life.’