 It might feel like humanity's history is inseparable from the violence that we see on TV and in history books. But for archaeologists who study ancient humans, violence between groups of hunter-gatherers isn't a given. In fact, some scientists think hunter-gatherers weren't prone to warfare at all. Now researchers say they've found 10 skeletons belonging to humans who died violently 10,000 years ago in Kenya. It's a rare find, and it could put to rest the myth of the peaceful hunter-gatherer. In 2012, archaeologists discovered remains belonging to at least 27 people in Nataruk, near an area that once held a small lagoon. A large number of these remains were broken and in bad shape. But the researchers managed to dig up 12 skeletons, 10 of which showed signs of lethal injuries. For example, one man had a projectile embedded in his skull, whereas another individual that may have been a woman had a perforating lesion on her forehead, signs of trauma on her jawbone, and a fractured hand. The researchers also found a tiny blade and two small tools made of flint embedded in two of the skeletons. Taken together, the injuries suggest that these people died at the hands of humans armed with bows and arrows. What's perhaps even more gruesome is that the two skeletons that didn't show signs of lethal injuries probably belonged to people who were tied up. The researchers know this because of the position of their hands, which appear to have been bound when they died. All in all, the fight led to the deaths of at least seven men and possibly five women. But what about the timing of the attack? To find out when these people died, the scientists use radiocarbon dating, a technique that uses the properties of carbon to assign dates to organic materials. They estimate that the bodies are between 9,500 and 10,500 years old. Which is significant because the West Turkana region of Kenya was home to a large population of hunter-gatherers during that period. And according to the authors, the timing of their deaths means that this is the earliest scientifically dated case of violence among different groups of hunter-gatherers. Not everyone agrees with that interpretation, however. Skeletons of possible hunter-gatherers who died in battle were discovered in the 60s in North Sudan, and they might actually be older according to two outside researchers. These skeletons are generally thought of as being between 12,000 and 14,000 years old. In addition, one researcher told us that there may not be enough evidence at the Narek site to solidly conclude that the skeletons belonged to hunter-gatherers. The study describes a very complex series of events that includes people being tied up and others being injured by projectiles, so it's possible that these events happened at different times. If so, this could be part of an ongoing fight between groups of people with more sedentary lifestyles. The truth is that archaeology isn't always cut and dry. After all, scientists still don't know why the humans in Kenya were murdered. It's possible that they died during a raid by another competing group. They could have been fighting over resources, like territory or food, the researchers say. Or the two groups may simply have had a very bloody and extremely unfortunate disagreement. Given the many, many reasons why humans kill each other today, it's not all that surprising that the same kinds of disputes might have led to the deaths of 12 people 10,000 years ago.