Original social network

Updated: Dec 31, 2021

Ostrich eggshell beads reveal 50,000 year old African social network.

Ostrich eggshells are far from dramatic finds in African archaeological sites. But they are beginning to tell an important story. While human DNA can tell us a great deal about genetic interactions between people, it doesn’t reveal anything about their cultural exchanges. Enter the humble ostrich eggshell bead, one of the most ancient exchange commodities in Africa. Ostrich eggshells are completely transformed when they are made into beads, which assume all manner of different forms.

Jennifer Miller and Yiming Wang of the Max Planck Institute for the Science of Human History have examined more than 1500 beads from 31 sites across eastern and southern Africa spanning a period of 50,000 years. Their unusual database took more than a decade to assemble. They compared shell thickness, bead diameters, and aperture dimensions with fascinating results. For example, between 50,000 and 33,000 years ago, people in both eastern and southern Africa were using nearly identical beads, as if there was a long distance social network that extended over more than 3,000km. This was the only period when the beads were identical, a time frame when climatic conditions were significantly wetter. By 33,000 years ago, the network had disappeared, most likely because of a major reduction in precipitation as the tropical rain belt shifted southward. The prolonged aridity up north increased rainfall in the enormous Zambezi River catchment, in South Central Africa, causing flooding that may have disrupted regional social networks.

Fortunately, ostrich eggshells beads are relatively common finds, so the Miller and Wang database has great promise for studying the details of long established ancient networks. The work is slow moving and usually unexciting, but the potential is significant.

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Above image: A string of modern ostrich eggshell beads from eastern Africa.

Credit: Hans Sell