TY - JOUR AU - McCarthy, Robert AU - Zimel, Emily PY - 2020/07/29 Y2 - 2024/03/29 TI - Revised estimates of Taung’s brain size growth JF - South African Journal of Science JA - S. Afr. J. Sci. VL - 116 IS - 7/8 SE - Research Article DO - 10.17159/sajs.2020/5963 UR - https://sajs.co.za/article/view/5963 SP - AB - <p>Cranial capacity, a proxy for the volume of the brain and associated cranial contents, is an important yardstick used to compare early hominin species because increasing brain size is a key characteristic of our lineage. In 1925, Raymond Dart claimed that a natural endocast found at the Buxton Limeworks near Taung, South Africa (which he named <em>Australopithecus africanus</em>), showed signs of neural reorganisation, but its juvenile status complicated comparison to other hominoid species. In an attempt to put its brain size and reorganisation into a comparative context, subsequent researchers have tried to estimate Taung’s adult cranial capacity by comparison to coarse-grained hominoid growth data. In this study, we simulated brain growth in <em>A. africanus</em> using asymptotic growth models in known-age mountain gorillas, chimpanzees and modern humans, and show that, at just under 4 years old, Taung’s brain had already finished or nearly finished growing according to hominoid developmental schedules. Percentage-growth remaining estimates are lower here than in previous studies using cross-sectional ontogenetic samples of unknown chronological age. Our new adult estimates (between 404 cm<sup>3</sup> and 430 cm<sup>3</sup> overall and 405–406 cm<sup>3</sup> for chimpanzee models) are smaller than previous estimates with a ‘starting’ cranial capacity of 404 cm<sup>3</sup>, supporting the hypothesis that Taung’s adult brain size would have fallen toward the lower end of the <em>A. africanus</em> range of variation and strengthening the case that Taung was female.</p><p><strong>Significance:</strong></p><ul><li>This is one of several recent studies to show that brain growth is completed in African apes and humans earlier than previously appreciated.</li><li>New adult cranial capacity estimates for Taung are lower than previous estimates, supporting the hypothesis that Taung was female.</li><li>Cessation of brain growth in hominoids at earlier ages than previously reported suggests that adult cranial capacities for hominin juvenile specimens have been overestimated.</li></ul><p><strong>Open data set:</strong></p><p><a href="http://dx.doi.org/10.17632/wyfvwd4s22">http://dx.doi.org/10.17632/wyfvwd4s22</a></p> ER -