Scientists and historians have long pondered when and how humans began warring. What conditions brought about massive conflict? Did intergroup violence arise with the agricultural revolution and property ownership? Or are humans inherently violent and war has always been part of our history?
The skeletons of 27 hunter-gatherers unearthed in East Africa may help answer those questions. Archeologists say that this group of people died quite violently some 10,000 years ago. Some died by having their heads bashed in by a blunt weapon, likely a club of some sort, while others were shot with a arrows or maybe stabbed with spears.
And as people weren't farming yet in the region, these skeletons are evidence potentially debunking the link between agriculture and the origins of war, the scientists write in a paper published Wednesday in the journal Nature.
"Anthropologists and archeologists have always been interested in the beginnings of warfare, intergroup conflict and whether war has been part of our history all along or whether it's a product of a particular environment or conditions," study coauthor Robert Foley tells The Christian Science Monitor in an interview.
One dominant theory suggests that when people settled down and began farming, societies arose in which property was important. Resources, like land or herds of farm animals, became something desirable to defend or steal.
But in that model, Dr. Foley says, "If you go back beyond those dates, you wouldn't expect warfare to be going on amongst hunter-gatherers."
So this set of remains, with clear markings of an altercation among people, appears to debunk such an explanation.
This isn't the first time researchers have suggested such prehistoric peoples engaged in violence. Burial pits discovered in a cave in Bavaria, Germany contained buried heads dating to the Mesolithic hinted at a violent encounter. Another burial site in Sudan revealed people living some 13,000 years ago had died of inflicted wounds. In 1996, an archeologist, Lawrence H. Keeley, even wrote a book, "War Before Civilization," to debunk "the myth of the peaceful savage."
"This is another nail in the coffin of the false Neo-Rousseauian idea that mobile hunter-gatherer bands, non-state, or uncivilized peoples are pacifists," Dr. Keeley, who was not involved in the study, tells the Monitor in an email.
But this study stands out from some of the others because the bodies likely weren't moved. Because these individuals were discovered where they died, the archeologists can paint a clearer picture of a single violent episode.
Nails in the hunter-gatherer coffin
The skeletons unearthed hold plenty of clues suggesting that these individuals died in a massive, violent fight.
These 10,000-year-old people were killed by a variety of weapons. Some of the skeletons display evidence of blunt force trauma with skulls smashed by a club or other sort of large, blunt object. But others still have pieces of a weapon, perhaps an arrow or spear, embedded where they were wounded in life.
The damage to the bones themselves aren't the only hints that this group of people died violently. These skeletons lay as they fell, eventually being covered by the elements over time rather than intentionally buried. The scientists looked at the way the bodies were positioned to learn more about their deaths.
Some of the skeletons' wrists or ankles were crossed as if they had been bound together. And two of those same skeletons display no evidence of the same violent trauma like some of the others.
This suggests a level of sophistication to the violence, says Nick Thorpe, an archeologist at the University of Winchester who was not part of the study. "It's not just a very brief violent encounter where you attack and kill these people and then you just go," he tells the Monitor in an interview. "Binding hands suggests something that takes more time."
When this altercation occurred, some of the bodies fell into a nearby lagoon, which might explain why the bound people died. Although the lagoon no longer exists, those conditions helped preserve the skeletons for the archeologists to find.
What were they fighting over anyway?
"We have the evidence to say this is the outcome, lots of dead people," Foley says. But, "it's much harder for us to go beyond that."
It's unlikely that this was an instance of two groups interacting and then exploding into violence. The variety of weapons and potentially bound individuals suggest that this altercation was more advanced than that.
So why were they fighting?
"Contrary to the claims of peaceful hunter-gatherers and/or nomadic bands, such groups had plenty of things to fight about: hunting territories, fishing stations, water sources, gathering plots, even young women and children," Keeley says.
The site where these skeletons were found, Nataruk, is west of Lake Turkana in Kenya. Although the region is dry and deserted now, 10,000 years ago it was much more lush. The lake was larger, there would have been lagoons to fish in, forests and lots of game to hunt. The land would have been a desirable place to set up camp.
But it might not have been just about land, Foley says. It could be resources more generally, perhaps even people.
Dr. Thorpe, the University of Winchester archeologist who was not part of the study, points out that very few teenagers were found among the group unearthed at Nataruk. He suggests that perhaps the other group of people took these young adults and somehow incorporated them into their own group.
Thorpe adds that if some of the individuals were bound, "perhaps these were people they were going to take with them but then died."
So are humans inherently violent?
Some researchers have suggested that humans are innately violent, physically clashing when encountering any conflict that arises. Scientists have looked at violence by chimpanzees, one of our closest living relatives, to point out such instinctual warfare.
But Thorpe suggests it's not that straightforward. Yes, this new find "reminds us that we have the capacity for violence," he says. But life is more complex, he says. People aren't simply brutish and violent or harmonious and peaceful.
Foley agrees. "Our history is not one of pure violence nor one of pure peace," he says. "It's much as our own lives are today. We live with both."
This study, led by Marta Mirazón Lahr, arose as part of the In Africa Project, a five year study investigating human origins in East Africa in the last 250,000 years.