11 Defining Homo erectus: Size Considered

Abstract

Homo erectus: for some a single, widely dispersed, polytypic species ultimately ancestral to all later Homo, for others a regional, Asian isolate, a sidebranch of later hominin evolution. In some views, the definition of H. erectus expands to include all Early and Middle Pleistocene fossils from Africa, Europe, and Asia, whereas other views exclude the European fossils and still others include only portions of the Asian fossil record. Temporally, H. erectus may thus span from 1.8 to perhaps 0.025Ma. In this chapter,we discuss the importance of body and brain size in the characterization of H. erectus.We also provide a historical review of the recovery of the fossil record of H. erectus because the understanding of its body size, the relationship between body and brain size, and the importance of the influence of scale on the cranial characters used in defining the taxon are all issues whose interpretation was in large part determined by the order and context in which fossil remains were recovered. We find evidence of clinal variation in stature in H. erectus, and across the taxon body size (stature) does not increase with time, whereas brain size gradually increases at a rate of about 160 cm3/Myr. Cranial characters, particularly those related to vault thickness and development of the supraorbital torus and many of those related to differentiating African fromAsian H. erectus, scale with brain size in H. erectus yielding little support for a differentiation between H. erectus and H. ergaster. In contrast, H. erectus is clearly differentiated from H. sapiens in terms of the scaling relationship between brain and body size and between brain size and several cranial measurements, including foramen magnum length. On these same relationships, it is difficult to differentiate the smallest H. erectus from the largest H. habilis.