Australopithecus sediba and the earliest origins of the genus Homo

Discovered in 2008, the site of Malapa has yielded a remarkable assemblage of early hominin remains attributed to the species Australopithecus sediba. The species shows unexpected and unpredicted mosaicism in its anatomy. Several commentators have questioned the specific status of Au. sediba arguing that it does not exceed the variation of Au. africanus. This opinion however, does not take into account that Au. sediba differs from Au. africanus in both craniodental and postcranial characters to a greater degree than Au.africanus differs from Au. afarensis in these same characters. Au. sediba has also been questioned as a potential ancestor of the genus Homo due to the perception that earlier specimens of the genus have been found than the c198 Ma date of the Malapa sample. This opinion however, does not take into account either the poor condition of these fossils, as well as the numerous problems with both the criteria used to associate them with the genus Homo, nor the questionable provenance of each of these specimens. This argument also does not acknowledge that Malapa is almost certainly not the first chronological appearance of Au. sediba, it is only the first known fossil occurrence. Au. sediba should therefore be considered a strong potential candidate ancestor of the genus Homo until better preserved specimens are discovered that would refute such a hypothesis.