Genetic and Morphological Records of the Hominoidea and Hominid Origins: A Synthesis

Abstract

Molecular genetics has had a major impact on phylogenetics, although many hominoid paleontologists and morphologists ignore or remain unaware of genetic data. However, substantial genetic evidence shows chimpanzees and humans as closest relatives. Living hominoids share many postcranial similarities, many of which are retained from the extant hominoid common ancestor. Miocene hominoid fossils consisted until recently mostly of teeth and jaw fragments which are relatively uninformative phylogenetically. As their postcrania have become better sampled, surprisingly few of these taxa share significant similarities with living apes, suggesting that few if any are related to specific extant lineages. Given the genetically inferred relationships of hominoids and the morphology of the earliest hominids, the common ancestor of humans and chimpanzees was probably chimp-like, a knuckle-walker with small thin-enameled cheek teeth. If correct, this scenario implies that known Miocene hominoids, most of which are postcranially archaic and have large, thickly enameled cheek teeth, throw little if any direct light on hominid origins.