It is generally accepted that archaic humans of the African later Early and early Middle Pleistocene constituted the source population for anatomically modern humans. Due to limited fossil and archaeological records, however, relatively little is known about the morphology, behaviour and ecology of these presumed ancestors of modern humans. Fragmentary fossils (variously attributed to Homo heidelbergensis, H. rhodesiensis and H. helmei) from across Africa suggest that these archaic humans were both taller and more massive than their extant modern human descendants in this region, and perhaps had a body shape that was stockier and less ‘nilotic’ than seen among extant sub-Saharan Africans. Fragmentary fossils attributed to Homo sapiens, on the other hand, appear to represent individuals closer in body size to the means of recent sub-Saharan Africans. Since body size and shape are critical to the ecology, energetics and thermoregulatory adaptations of early humans, these differences in morphology may signal important adaptive changes at the time of the origins of modern humans. Comparative analyses of femoral and orbital dimensions support the claim that Middle Pleistocene Africans were of greater body size (both stature and mass) and had greater mass/stature ratios than modern Africans, and support the claim that early African H. sapiens were of smaller body size than their Middle Pleistocene ancestors.