Stone-Age social networks

A study of ostrich eggshell bead exchange in the late Middle Stone Age reveals that relationships among hunter-gatherers in southern Africa existed across hundreds of kilometers. Early systems of reciprocal gifting of small, portable items served to cement relationships among hunter-gatherer groups, providing extended networks in times of need. However, the extent and age of such systems in Africa are unclear. Brian Stewart and colleagues analyzed eggshell beads, spanning a 33,000-year period, from two locations in the highlands of Lesotho in southern Africa. The work revealed that by the late Middle Stone Age relationships among hunter-gather groups in southern Africa existed across hundreds of kilometers. Strontium isotope levels in an ostrich eggshell reflect the amount of strontium in the bird’s breeding territory, and preliminary mapping of the surrounding area’s strontium concentrations showed that the amount of bioavailable strontium increases with distance from the highlands and that excavated beads originated from lower rock formations. Based on interpretation of historical ostrich range, the authors deduced that all of the sampled beads originated more than 100 km away, with some coming from farther than 300 km. According to the authors, the size of the network implied by the distances, which covered eight different bioregions, would have provided groups with access to high ecological diversity and offered a social strategy to buffer against times of scarcity.

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Article #19-21037: ” Ostrich eggshell bead strontium isotopes reveal persistent macroscale social networking across late Quaternary southern Africa,” by Brian A. Stewart et al.

MEDIA CONTACT: Brian A Stewart, University of Michigan-Ann Arbor, MI; e mail:

[email protected]