The hominids recovered from the early Pleistocene in Africa appear to constitute two distinct lineages. The first consists of gracile forms characterized by small cheek teeth and relatively large canines and incisors. All of these creatures have been assigned to the genus Homo (Robinson, 1967), and to this group may be referred Homo transvalensis from Sterkfontein, Taungs, and Makapansgat (formerly called Australopithecus africanus); H. habilis from Bed I at Olduvai Gorge; and H. erectus from Swartkrans (formerly called Telanthropus capensis).1 The second line is composed of more robust forms possessing larger cheek teeth and relatively smaller anterior dentitions. Included therein are the following: Paranthropus robustus from Kromdraii and Swartkrans; P. boisei from Olduvai Gorge, Bed I (formerly called A. [Zinjanthropus] boisei); and the Peninj mandible which represents a population similar to P. boisei. The anatomical differences with regard to the trophic apparatus-and these involve more than simply the relative size of the cheek teeth (See Robinson, 1963, 1967, and elsewhere) -suggest differences in diet. The usual presumption is that the gracile forms were more omnivorous than their robust cousins. The latter are believed to have specialized more exclusively in vegetable matter (Robinson, 1963, 1967, and elsewhere). In two regions, Olduvai Gorge and Swartkrans, remains of both types have been found together in such a manner as to render unquestionable the belief that these populations cooccured in time and space (Robinson, 1953; Tobias, 1965).