Endocranial capacity in Sts 71 (Australopithecus africanus) by three-dimensional computed tomography

In a recent report on early hominid endocranial capacity, it was predicted that future studies would show that: (1) "several key early hominid endocra nial estimates may be inflated"; (2) "current views on the tempo and mode o f early hominid brain evolution may need reevaluation"; and (3) endocranial capacity in one of these, Sts 71, was "probably closer to 370 cm(3), very near the mean value for female chimpanzees, and not the currently accepted 428 cm(3)" (Conroy et al., Science, 1998; 280: 1730-1731; Falk, Science 199 8; 20: 1714). Subsequent studies tend to support the first two predictions, but not the third (Culotta, Science, 1999; 284: 1109; Falk, Am. J. Phys. A nthropol. Suppl., 1999; 28: 126; Falk et al., J. Hum. Evol. [in press]). He re we detail the reasons for thinking the currently accepted endocranial va lue for Sts 71 is probably correct by providing the first quantitative deta ils of endocranial reconstruction in Sts 71 using three-dimensional compute d tomography. Relative brain expansion in the hominid lineage started some half-million years before the earliest appearance of the genus Homo, possib ly coincident with enhanced tool-making skills and carnivory. Anat Rec 258: 391-396, 2000. (C) 2000 Wiley-Liss, Inc.