Variation, sexual dimorphism and the taxonomy of australopithecus

After more than a century of research, the extent of sexual dimorphism in the early Hominidae continues to concern anthropologists. In paleoanthropology, the phenomenon of intraspecific variation presents a difficult and pivotal challenge. As Walker and Leakey (1978) recognized, the first and most fundamental issue in the analysis of fossil hominid samples is the determination of how many species they contain. Discerning sexual dimorphism from interspecific variation, for example, currently plagues attempts to circumscribe taxonomically the recently enlarged samples of Miocene Hominoidea. Analogous problems have been prominent in debates concerning the status of the Hadar collection of Australopithecus afarensis and the KoobiFora collection of Homo habilis. This chapter presents quantitative and qualitative data bearing on variation in the skull and dentition of Australopithecus. Our purpose is to examine the contribution of sex to this variation in the light of ongoing discussions about the taxonomy of early hominids.