On the tiny island of Bryher, off the southwest coast of England, a farmer happened upon a grave in 1999 that proved particularly intriguing. The grave dated to late in the Iron Age (ca. 750 B.C.–A.D. 43). It contained an iron sword sheathed in a copper alloy scabbard and a shield made of wood or animal hide, weapons typically associated with male burials in the area. It also held a bronze mirror, an object more commonly associated with female burials. The skeletal remains added up to just 5.3 ounces of bone and teeth and were so degraded that it was impossible to determine the deceased’s sex. “This is the richest grave in southwest England from the Iron Age,” says Sarah Stark, a human skeletal biologist with Historic England. “That told us this was someone of great importance, but we were limited in terms of how far we could go in unraveling the mystery of who this person may have been.”

Using a technique that analyzes proteins in tooth enamel—the most durable part of the body—researchers have now been able to determine that the deceased was almost definitely female. The technique identified proteins associated with the X chromosome but not the Y chromosome, which is inherited by all males. This finding has led researchers to reevaluate the role this woman would have played on Bryher during the Iron Age, a time when violence is known to have been common, particularly in the form of raids on rival communities. “Based on the objects in her grave,” says Stark, “we think she had some sort of leadership role, whether that was planning, organizing, or leading raids.” She may have used the mirror to signal other warriors during battle or in cleansing rituals before or after a clash.