At a site in northern Kenya near Lake Turkana, archeologists found 27 bodies they believe were victims of a brutal massacre that took place more than 10,000 years ago. Among the remains were 21 adults -- eight females, eight males and five whose sex couldn't be determined -- and the partial remains of six children.
"No children were found with or near any of the men. All except one of the juvenile remains are children under the age of 6; the exception is a teenager, aged 12-15 years dentally, but whose bones are noticeably small for their age," the authors of the study wrote.
Scientists first unearthed the site in 2012, and their findings have now been published in a study spearheaded by Cambridge University and the Turkana Basin Institute
Researchers say the discovery at Nataruk is likely the oldest evidence of human warfare.
The wounds on the bodies were severe.
The skull of one man had a "bladelet of obsidian volcanic rock" embedded in it. At least five of the dead had suffered from "blunt-force trauma to the head." A woman's body was found with the hands and feet bound. She was more than six months pregnant.
Also discovered were the weapons used in this blitz attack, including clubs, stone blades and arrows. The massacre happened on the banks of a lagoon, and some of the bodies fell into the water, helping to preserve them.
The victims were left to die where they lay, the study said, "with no evidence of deliberate burial."
Discovery challenges theories of war
While there are different theories as to what led to war throughout evolution, most scientists believed that battles arose with human settlement.
"The underlying theory is that one group wants what the other group has, power, land -- two groups competing for the same thing," said University of Cambridge paleoanthropologist Dr. Marta Mirazon Lahr.
But the remains discovered in northern Kenya were those of hunter-gatherers.
"Our discovery is particularly interesting because it is a conflict, an intentional conflict, among a group of hunter-gatherers that in theory did not have ownership or possession of things that would lend themselves to such attacks."
Adding to the mystery, the attack took place in a fertile region, where food and resources were abundant. This, Lahr said, might suggest that the Nataruk people had possessions -- such as meat or dried fish, or possibly even women and children -- that others would consider worth killing for. Because there was only one teenager among the dead, Lahr suspects the attack may have been a raid to abduct the young people in the group.
"We read every day about an act of violence somewhere in the world," said Lahr. "That behavior has been with us for a long time."
"But I also think that we are unique in the animal world because we also do things that we derive no benefit at all. People are compassionate and caring and that is another aspect of human behavior and that is totally unique to us."