DAVIS, CALIFORNIA—The remains of seven men, discovered in a mass grave at a construction site outside San Francisco in 2012, have been studied by a team led by Jelmer Eerkens of the University of California, Davis. All of the men, who were between the ages of 18 and 40 at the time of death some 1,150 years ago, had suffered physical trauma. The bones showed signs of head wounds and broken limbs, and weapons made of stone and obsidian were discovered among the skeletons. Eerkens’s study revealed that all of the men had died around the year A.D. 850, a time when hunter-gatherer groups in central California were on the move. “Such resettlement may have brought them into conflict with groups that were already living there,” Eerkens told Western Digs. Analysis of the men’s teeth showed that they had all grown up in an area where they ate freshwater fish, probably in the San Joaquin Valley. And mitochondrial DNA from the bones suggests that men were not brothers or maternal cousins. “This suggests to us that warfare or raiding was conducted by people who lived in the same or nearby villages, but who were drawn from different households and families,” he said. To read about a later discovery in California, go to "A New Look at the Donner Party."