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Phylogenetic Analysis of Early Hominids [and Comments and Reply]

1986; University of Chicago Press; Volume: 27; Issue: 1 Linguagem: Inglês

10.1086/203377

1537-5382

Randall R. Skelton, Henry M. McHenry, Gerrell M. Drawhorn, Alan Bilsborough, Andrew Chamberlain, Bernard Wood, Václav Vančata,

Primate Behavior and Ecology

The proposal of the new australopithecine species Australopithecus afarensis has led to a multiplicity of hypotheses concerning the evolutionary relationships between the known Pliocene and Pleistocene hominid species. We use phylogenetic analysis to gain a new perspective on the subject. Using 69 traits, we construct a series of 12 complexes, each with a defining polarized morphocline. Four mutually exclusive cladograms are derived from these complexes, the most parsimonious of which implies that Homo habilis and A. robustus/boisei are more closely related to each other than either is to A. africanus and that these three species form a distinct evolutionary group relative to the more primitive A. afarensis. We advocate a phylogeny wherein A. afarensis is ancestral to A. africanus, which is in turn ancestral to A. robustus/boisei and H. habilis. We believe that the evolutionary transition from Australopithecus to Homo involved reduction in the size of the chewing teeth and associated traits leading to a unique derived condition in H. habilis that superficially resembles the primitive condition of A. afarensis. Five other current phylogenies are treated as critiques of this one.