Figure 1.

Plio-Pleistocene dispersals of African mammals. (a) Three waves of mammalian dispersal (1), including a southward dispersal at 3.0 Myr of Canis, Diceros, Australopithecus, and Metridiochoerus, a northward dispersal between 2.7 and 2.0 Myr of Cercopithecoides, Connochaetes, Parmularius, Tragelaphus, and Antidorcas, and a southward dispersal between 1.8 and 1.5 Myr of Theropithecus, Nyctereutes, Equus, Metridiochoerus, Homo, Kobus, Hippotragus, and two species of Tragelaphus. Hipparion disperses northward at 1.7 Myr when other mammals are dispersing southward. Each wave of dispersals is either significantly or nearly significantly different from random. Other studies have placed H. habilis in the northward event (2) and P. robustus in the late southward event (3), and H. rudolfensis may have dispersed with other eastern African mammals into the Corridor at ≈2.4 Myr (2). (b) Early hominid dispersals implied by Fig. 2 b, c, and e (29, 30), under the assumption that H. habilis originated in eastern Africa (see Table 1). The direction of the H. rudolfensis dispersal is unclear. Different patterns are implied if H. habilis originated in southern Africa. Fig. 2b also includes a northward migration at ≈2.7 Myr of the common ancestor of Homo and Paranthropus (not shown).