Comment on the Paleobiology and Classification of Ardipithecus ramidus

Abstract

White and colleagues (Research Articles, 2 October 2009, pp. 64-106 and www.sciencemag.org/ ardipithecus) reported Ardipithecus ramidus as an exclusive member of the human lineage post-African ape divergence. However, their analysis of shared-derived characters provides insufficient evidence of an ancestor-descendant relationship and exclusivity to the hominid lineage. Molecular and anatomical studies rather suggest that Ar. ramidus predates the human/ African ape divergence.

Primate origins, human origins, and the end of higher taxa

“…117 The affinities and adaptations of Ardipithecus remain controversial. [118][119][120] But there is conclusive evidence that a lot of supposedly human features were acquired in parallel in different lineages of Pleistocene hominins. Probable parallelisms include the increased basicranial flexion and other basicranial apomorphies seen in late robust Australopithecus species 53:194 ; molar reduction and humanlike changes in the pelvis and hand in A. sediba [121][122][123] ; brain enlargement in some habilines (KNM-ER 1470) and facial and dental reduction in others (KNM-ER 1813); and so on.…”

Response to Comment on the Paleobiology and Classification of Ardipithecus ramidus

“…armiento (1) doubts that Ardipithecus ramidus represents a cladistic hominid (phylogenetically on the human side of our divergence with chimpanzees). He argues that biomolecular studies accurately converge on a divergence date of approximately 3 to 5 million years ago, concluding that Ar.…”

“…Feminization of the male Ardipithecus C/P 3 complex is robustly documented [detailed in the supporting online material in (7)] and is incompatible with Sarmiento's argument that Ar. ramidus represents the stem taxon for both African apes and humans (1). If that were the case, a hominid-like C/P 3 complex with lack of honing would need to have evolved in Ar.…”

The First Hominins and the Origins of Bipedalism

“…As a note of caution, given its recent announcement, many scientists feel that it's still early days with this specimen. Some researchers have even begun to question its hominin status (Harrison 2010;Sarmiento 2010), but we have to wait until more information and full descriptions become available.…”