The Taung child and the biogeographic and palaeoclimatic drivers of southern African hominin diversity

The discovery of the Taung child, the holotype of Australopithecus africanus, marked a turning point in palaeoanthropology and stimulated the search for hominin fossils in Africa. Despite numerous Plio-Pleistocene hominin discoveries, particularly in eastern and southern Africa, Taung’s evolutionary position and relationship to other hominins remains unclear. Here we explore whether an eco-evolutionary range dynamics framework can help explain early hominin diversity in southern Africa. Focusing on the Taung child -the only unequivocal A. africanus specimen- we first reassess the site’s chronological age and examine the fossil’s dental and brain development, and M1 dentino-enamel junction variation. These analyses confirm that A. africanus is a poorly defined taxon. Based on new palaeoclimatic and palaeoenvironmental evidence, combined with considerations about South Africa’s geographic position and the Zambezian–southern African biogeographic boundary, we propose that complex population dynamics, including drift and hybridisation, probably underpin hominin morphological diversity in southern Africa during the Plio-Pleistocene.