Abstract

Interpreting morphological variation within the early hominin fossil record is particularly challenging. Apart from the fact there is no absolute threshold for defining species boundaries in palaeontology, the degree of variation related to sexual dimorphism, temporal depth, geographic variation, ontogeny or even pathologies is difficult to appreciate in a fossil taxon mainly represented by fragmentary specimens, and such variation could easily be conflated with taxonomic diversity. One of the most emblematic examples in paleoanthropology is the Australopithecus assemblage from the Sterkfontein Caves in South Africa. Whereas some studies support the presence of multiple Australopithecus species at Sterkfontein, others explore alternative hypotheses to explain the morphological variation within the hominin assemblage. Far from being anecdotal, evidence supporting the presence of multiple Australopithecus species at Sterkfontein would deeply affect our understanding of early hominin taxonomic diversity, ecology and speciation. In this paper I review and evaluate taxonomic interpretations of the Australopithecus assemblage recovered from Sterkfontein as well as their implications for our understanding of evolutionary mechanisms.