VALLADOLID, SPAIN—According to a statement released by the Nature Publishing Group, a team of researchers led by Teresa Fernández-Crespo of the University of Valladolid and her colleagues examined the remains of 338 individuals recovered from a mass grave in northern Spain. The bones were radiocarbon dated to between 5,400 and 5,000 years ago. More than 50 flint arrowheads were also recovered from the pit. A previous study determined that more than 30 of these points bore minor damage associated with hitting a target, while the new analysis of the bones determined that more than 20 percent of the individuals had skeletal injuries, and about 10 percent of them had unhealed injuries. More than 74 percent of the unhealed injuries, and 70 percent of the healed injuries, were found on the remains of adolescent boys and adult men. Fernández-Crespo and the members of her team suggest that many of those buried at the site may have been exposed to violence and were perhaps the casualties of a conflict between the different cultural groups that lived in the region during the Late Neolithic period. The presence of healed injuries suggests that the conflict may have lasted several months, they explained. Read the original scholarly article about this research in Scientific Reports. To read about evidence for the ritual killing of a lion by hunter-gatherers in northern Spain more than 15,000 years ago, go to "When Lions Were King: Rituals."