The evolution of human and ape hand proportions.

Bibliographic Collection: 
APE
Publication Type: Journal Article
Authors: Almécija, Sergio; Smaers, Jeroen B; Jungers, William L
Year of Publication: 2015
Journal: Nat Commun
Volume: 6
Pagination: 7717
Date Published: 2015
Publication Language: eng
ISSN: 2041-1723
Keywords: Animals, Biological Evolution, Fingers, Fossils, Gorilla gorilla, Hand, Hominidae, Humans, Organ Size, Pan troglodytes, Phylogeny, Pongo
Abstract:

Human hands are distinguished from apes by possessing longer thumbs relative to fingers. However, this simple ape-human dichotomy fails to provide an adequate framework for testing competing hypotheses of human evolution and for reconstructing the morphology of the last common ancestor (LCA) of humans and chimpanzees. We inspect human and ape hand-length proportions using phylogenetically informed morphometric analyses and test alternative models of evolution along the anthropoid tree of life, including fossils like the plesiomorphic ape Proconsul heseloni and the hominins Ardipithecus ramidus and Australopithecus sediba. Our results reveal high levels of hand disparity among modern hominoids, which are explained by different evolutionary processes: autapomorphic evolution in hylobatids (extreme digital and thumb elongation), convergent adaptation between chimpanzees and orangutans (digital elongation) and comparatively little change in gorillas and hominins. The human (and australopith) high thumb-to-digits ratio required little change since the LCA, and was acquired convergently with other highly dexterous anthropoids.

DOI: 10.1038/ncomms8717
Alternate Journal: Nat Commun