Researchers from the Max Planck Institute for the Science of Human History's Department of Archaeology present an expanded analysis of African ostrich eggshell beads, testing the hypothesis that larger beads signal the arrival of herders.
     Ostrich eggshell beads are some of the oldest ornaments made by humankind, and they can be found dating back at least 50,000 years in Africa. Previous research in southern Africa has shown that the beads increase in size about 2,000 years ago, when herding populations first enter the region. In the current study, researchers Jennifer Miller of the Max Planck Institute for the Science of Human History and Elizabeth Sawchuk of Stony Brook University tested the idea that the size of beads made from ostrich eggshells can be used to track cultural shifts in ancient Africa.
     To conduct their study, the researchers recorded the diameters of 1,200 ostrich eggshell beads unearthed from 30 sites in Africa dating to the last 10,000 years. Many of these bead measurements were taken from decades-old unstudied collections, and so are being reported here for the first time. This new data increases the published bead diameter measurements from less than 100 to over 1,000, and reveals new trends that oppose longstanding beliefs.
     Miller and Sawchuk confirmed that larger beads appeared in southern Africa some 2,000 years ago, when people began to herd sheep and goats, but did not replace existing bead styles. The larger bead size may have been introduced by the people who brought domesticated animals to the region, they explained. In eastern Africa, however, bead styles did not change at the time herding was introduced, although beads made by foragers in eastern Africa were similarly sized to the larger beads made by herders in southern Africa.
     The data reveals a more nuanced interpretation that provides greater insight into the history of economic change and cultural contact. The researchers conclude that peoples from southern and eastern Africa may have had contact with each other as herding spread, but the experience did not extinguish local traditions. "These beads are symbols that were made by hunter-gatherers from both regions for more than 40,000 years," says lead author Jennifer Miller, "so changes - or lack thereof - in these symbols tells us how these communities responded to cultural contact and economic change."
     The researchers hope that this work inspires a renewed interest into ostrich eggshell beads, and recommend that future studies present individual bead diameters rather than a single average of many. Future research should also investigate questions related to manufacture, chemical identification, and the effects of taphonomic processes and wear on bead diameter.

Edited from Max Planck Institute, Plos One, ScienceDaily (27 November 2019)