The evolution of human and ape hand proportions

• DOI: 10.1038/ncomms8717
• Publication Date: 2015-07-14T15:09:49Z
• Authors: Sergio Almécija; Jeroen B. Smaers; William L. Jungers
• Keywords: Autapomorphy; Hominidae; Convergent evolution; Australopithecus

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