Body Size, Body Shape, and the Circumscription of the Genus Homo

Since the 1984 discovery of the Nariokotome Homo erectus/Homo ergaster skeleton, it has been almost axiomatic that the emergence of Homo (sensu stricto) was characterized by an increase in body size to the modern human condition and an autapomorphic shift in body proportions to those found today. This was linked to a behavioral shift toward more intensive carnivory and wider ranging in the genus Homo. Recent fossil discoveries and reanalysis of the Nariokotome skeleton suggest a more complex evolutionary pattern. While early Homo tend to be larger than Australopithecus/Paranthropus, they were shorter on average than people today. Reanalysis of the Nariokotome pelvis along with the discovery of additional early and middle Pleistocene pelves indicate that a narrow bi-iliac (pelvic) breadth is an autapomorphy specific to Homo sapiens. Likewise, it appears that at least some early Homo (even those referred to H. ergaster/H. erectus) were characterized by higher humero-femoral indices than the H. sapiens average. All these data suggest a pattern of mosaic postcranial evolution in Homo with implications for the increased ranging/carnivory model of the origin of Homo as well as for which species are included within the Homo hypodigm.