Early Pleistocene third metacarpal from Kenya and the evolution of modern human-like hand morphology.

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Ward, Carol V; Tocheri, Matthew W; Plavcan, J Michael; Brown, Francis H; Manthi, Fredrick Kyalo
Year of Publication: 2014
Journal: Proc Natl Acad Sci U S A
Volume: 111
Issue: 1
Pagination: 121-4
Date Published: 2014 Jan 7
Publication Language: eng
ISSN: 1091-6490
Keywords: Animals, Anthropology, Physical, Biological Evolution, Bone and Bones, Female, Fossils, Hominidae, Humans, Kenya, Male, Metacarpal Bones

Despite discoveries of relatively complete hands from two early hominin species (Ardipithecus ramidus and Australopithecus sediba) and partial hands from another (Australopithecus afarensis), fundamental questions remain about the evolution of human-like hand anatomy and function. These questions are driven by the paucity of hand fossils in the hominin fossil record between 800,000 and 1.8 My old, a time interval well documented for the emergence and subsequent proliferation of Acheulian technology (shaped bifacial stone tools). Modern and Middle to Late Pleistocene humans share a suite of derived features in the thumb, wrist, and radial carpometacarpal joints that is noticeably absent in early hominins. Here we show that one of the most distinctive features of this suite in the Middle Pleistocene to recent human hand, the third metacarpal styloid process, was present ∼1.42 Mya in an East African hominin from Kaitio, West Turkana, Kenya. This fossil thus provides the earliest unambiguous evidence for the evolution of a key shared derived characteristic of modern human and Neandertal hand morphology and suggests that the distinctive complex of radial carpometacarpal joint features in the human hand arose early in the evolution of the genus Homo and probably in Homo erectus sensu lato.

DOI: 10.1073/pnas.1316014110
Alternate Journal: Proc. Natl. Acad. Sci. U.S.A.