An ancient cemetery has revealed recurring violence in the Nile Valley that was likely due to ancient climate change, according to a paper published Thursday.

The remains at Jebel Sahaba, a 13,400- to 18,600-year-old gravesite in Sudan near the border with Egypt, were excavated in the 1960s. Because the earlier analyses found evidence of wounds on the bones of 20 of 61 people buried there, a prevailing theory was that they had been the victims of a massacre. However, in a reanalysis of 61 people's remains, published in Scientific Reports, researchers have debunked that theory by identifying both healed and unhealed wounds. The healed wounds indicate that this wasn't just one massacre: Violence was an ongoing feature of these people's lives.

"There was no clear evidence of the recurrence of the interpersonal violence with projectile weapons until we discovered healed lesions with embedded lithic [fragments] on some skeletons," said Isabelle Crevecoeur, the lead author of the paper and a researcher at the Centre National de la Recherche Scientifique. The paleoanthropologist told The Academic Times, "This careful examination of all the remains took us six years, but we are now very happy with the results."

Crevecoeur and her colleagues confirmed most of the wounds described by the first researchers, who published their work in the 1960s. But they also found wounds on 21 more people, noting a total of 106 previously unidentified wounds. Three-quarters of the adults in the cemetery had wounds, and 15 people had both healed and unhealed lesions.

The researchers do not believe there were face-to-face battles happening: The projectiles hit these people from both the front and the back. It is likelier, they wrote, that the community suffered "small episodes of recurring violent events such as raids or ambushes."

There was no particular gender difference in the violence these people experienced, except that women had more defensive wounds on their arms, probably incurred during close combat. "This type of fracture — breakage of the ulna at midiaphysis — is mostly related to instinctive movement of the forearm placed in front of the head to protect oneself from a coming blow," Crevecoeur said. "Some parry fractures could of course sometimes be accidental, but the literature on traumatic paleopathology is quite consistent regarding this pattern of breakage being related to defensive action. It is, for example, completely different from the type of forearm fracture that can be caused by a bad fall."

There were 11 people with projectile impact marks who still had little pieces of stone in their bones, flaked off from the weapon that cut them. Notably, the people at Jebel Sahaba were wounded with a variety of weapons: The points that hit them and, in some cases, broke off inside their bodies included both smaller, lighter points that might have been on light arrows and wider, heavier points that might have been on spears. Many of the points had cutting edges that seemed designed to slash and cause blood loss.

Crevecoeur and her colleagues also found evidence that the people at Jebel Sahaba tried to address their injuries. In one individual, "One border of the cut is clearly stripped and broken toward the external part of the puncture, which would happen during the extraction of the projectile," Crevecoeur said. "The embedded lithic inside the puncture was probably trapped too deep in the bone and detached itself from the weapon during its removal, creating additional pressure to the external border of the bone."

It is also possible that the individual, who researchers believe was likely a woman over 30, was hit by a projectile while she was running. "When an arrow is thrown, you would expect a top-to-bottom trajectory in general," Crevecoeur said, but the trajectory of this projectile looked like she'd been hit from below her feet. Either she was running and got hit mid-stride, or she was hit by someone below her on a slope, Crevecoeur explained.

In the original analyses, researchers identified 61 individuals buried on their left side in the cemetery. However, the new analysis found additional bones that could not have belonged to the already-identified individuals; thus, at least 64 people were buried at Jebel Sahaba. The human remains were excavated in the '60s before a dam was set to flood the area; the late American archaeologist Fred Wendorf took the remains from the Nile Valley and later donated them to the British Museum. The remains of three individuals described in the original published research have gone missing.

Crevecoeur said she first examined the remains in 2004 and "always wanted to go back to this amazing collection to work on behavioral questions." Crevecoeur and one of her co-authors, Marie-Hélène Dias-Meirinho, began work in 2013.

They've now disproven a decades-old theory. "The co-occurrence of healed and unhealed lesions strongly supports sporadic and recurrent episodes of interpersonal violence between Nile Valley groups at the end of the Late Pleistocene," the authors wrote. Environmental pressures caused by climate change at the beginning of the African humid period may have spurred this violence and unrest — a history of human suffering that still has relevance today, as contemporary people face the fallout of human-induced climate disaster.

The paper, "New insights on interpersonal violence in the Late Pleistocene based on the Nile Valley cemetery of Jebel Sahaba," published May 27 in Scientific Reports, was authored by Isabelle Crevecoeur, Centre National de la Recherche Scientifique and Université de Bordeaux; Marie‑Hélène Dias‑Meirinho and François Bon, Université de Toulouse Jean Jaurès; Antoine Zazzo, Centre National de la Recherche Scientifique; and Daniel Antoine, British Museum.