Scientists have made a grisly discovery at what was once a lagoon in Kenya: The remains of 27 people, including eight women and six children, who were violently killed some 10,000 years ago.
One of the victims was a pregnant woman who appeared to have been bound.
Another was a man who took an arrow to the head and apparently survived, only to die from a crushing blow to the right side of his head. The obsidian arrow was still there, embedded in his skull.
Two other men had stone projectiles wedged in the skull and thorax.
The Cambridge University researchers who uncovered the scene said it wasn't a burial site. In fact, the bodies preserved in lagoon sediment hadn't been buried at all.
What they found in Nataruk, near Lake Turkana, was the site of a massacre, the oldest ever uncovered, according to a study published this week in the journal Nature.
Dated to between 9,500 and 10,500 years ago, the scene uncovered by researchers from Cambridge University’s Leverhulme Centre for Human Evolutionary Studies (LCHES) was the earliest known example of a historical conflict.
"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," study leader Marta Mirazón Lahr of Cambridge said in a news release.
Remains uncovered in Sudan also showed violent deaths and were believed to be of a similar age, but those bones have never been dated, the news release said.
However, unlike the remains in Kenya, the Sudanese bones were buried in a cemetery.
Of the remains found in Kenya, 12 were complete skeletons. Ten showed what Cambridge described as "clear signs of a violent death."
Five appeared to have been clubbed to death, showing signs of blunt-force trauma to the head. One set of remains showed hits on both sides of the head, causing his skull to crack in different directions.
Some of the bodies were found face-down, and the research team said they were either an extended family or a tribe of foragers.
The researchers don't know why the group was attacked so violently, but they can guess.
"The Nataruk 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,” said Mirazón Lahr.
She also said it could have just been "a standard antagonistic response to an encounter between two social groups at that time."
"I’ve no doubt it is in our biology to be aggressive and lethal, just as it is to be deeply caring and loving," study co-author Robert Foley, also from Cambridge’s LCHES, said in the news release. "A lot of what we understand about human evolutionary biology suggests these are two sides of the same coin."
For more on the discovery watch the video below.