From earrings and necklaces to lipstick and tattoos, humans across cultures decorate themselves. Yet exactly how and why this practice came about has proved somewhat of a mystery, owing to holes in the archaeological record. Findings announced today in the early online edition of the Proceedings of the National Academy of Sciences, however, are offering new insight. According to the report, the technology for making body ornaments such as beads and pendants emerged simultaneously in Europe, Asia and Africa more than 40,000 years agoperhaps as a new form of communication among the expanding populations in these regions.

Previous work had turned up ancient ornaments crafted from shells, teeth, ivory and stone dating to the early Upper Paleolithic period in Africa and Europe. The new research, conducted by Steven L. Kuhn and Mary C. Stiner of the University of Arizona and their colleagues, shows that people in the Levant were making ornaments back then too. Recent excavations at a cave in Turkey and reappraisal of some Lebanese remains, the team reports, have revealed shell beads that are at least 41,000 years old.

These Upper Paleolithic ornaments and their contemporaries in eastern Europe and Africa may well not be the oldest nonutilitarian artifacts known, the authors acknowledge. But unlike the handful of putative ornaments from Africa and Eurasia dating back to at least 120,000 years ago, the later materials are relatively abundant and occur in standardized forms that persisted for thousands of years. As such, the team writes, "they can be characterized as part of a shared system of communication."

Though scientists cannot know for certain what such decorations stood for, Kuhn and his colleagues suggest that if recent human societies are any indication, our ancestors may have used these ornaments to convey to strangers aspects of social identity, such as group membership, gender, age and marital status. That the tradition appeared on three continents at roughly the same time, they note, may reflect the fact that populations at that time were growing, making the chances of meeting strangers relatively high.