An ancient human skull found in China shows evidence of blunt force trauma, meaning some other human probably hit him on the head. Considering how old the skull is, this might as well be considered the invention of violence.
Of course, violence - even of the human-on-human variety - existed long before this human got his or her bump on the noggin, but this is the earliest known instance of a wound that was likely the result of another human's attack. The trauma was to the ancient person's right temple, and the most likely explanation is that it was caused by an object thrown by somebody else. The skull was first discovered in a cave near Maba, China in 1958, but it's only now that researchers have recognized the possible significance of the wound on its skull.
Washington University in St. Louis researcher Erik Trinkaus explains that the violence hypothesis isn't the only explanation, but he does think it's the most likely:
"There are older cases of bumps and bruises - and cases of trauma. But this is the first one I'm aware of where the most likely interpretation is getting whooped by someone else - to put it bluntly. One of the problems was that these people led rough lives. They were hunting medium-to-large animals at close quarters. And when you stick a spear in an animal, they usually do not appreciate it. They tend to kick and fight - and many of these animals had horns and antlers. Can we completely rule out a hunting accident? No. But it's less likely to be that than getting hit on the side of the head with a missile."
Trinkaus describes the injury as "very directed, very localized", possibly the result of being hit by something like a stone cobble. Based on the healed nature of the fracture, the person survived the injury for weeks or months at the very least, though it's entirely possible that the injury did cause some temporary amnesia. As he points out, this is just one of many findings that show ancient humans suffering serious injuries - but perhaps more importantly, also surviving them:
"It's another individual in a growing number of human fossils going back in excess of a million years who show long-term survival with serious injuries and congenital problems - a variety of things along these lines. We have many instances of trauma - some serious, some minor. We also have a surprisingly high incidence of conditions that occur in the modern world but are extremely rare. So the probability of finding them in our meagre fossil record is extremely low...[Ancient humans] are surviving them remarkably well. They hit each other, they squabbled, they had weaponry - so it became serious. But at the same time, they were helping each other out.
Indeed, Trinkaus says a finding like this reveals the existence of ancient support and care networks that would allow someone like Maba man to survive the injury just as much as it does the initial violence that caused the injury. This particular individual is likely not one of the ancestors of modern humans, but instead one of the related groups of humans that lived on the Eurasian landmass hundreds of thousands of years ago.
It's possible that Maba man is an example of the Denisovan population that was identified last year, but Trinkaus says it will likely be difficult to place the different groups of ancient humans in such clearly delineated categories. Instead, he says the Eurasian branch of humanity existed on a continuum, with Neanderthals representing the extreme western end, and specimens like Maba man representing the eastern side.