Chimpanzee hands more evolved than human hands

[hamster]

Yeah well they still can't type as fast as I can

[rogue06]

A new study reveals that the human hand is actually more primitive than the hands of our closest primate ancestors: chimpanzees. The study determined that while the proportions of the human hand closely resemble those of the last common ancestor of chimps and humans which lived some 6 to 7 mya, the hands of chimps and orangutans have actually evolved quite a bit.

Sergio Almécija, a paleoanthropologist at George Washington University's Center for the Advanced Study of Human Paleobiology and the Department of Anatomical Sciences at Stony Brook University, who headed the study notes that the results indicate that because the overall hand proportions of humans are largely primitive, when the first members of the human lineage started to use and produce complex stone tools in a systematic way, "their hands were already pretty much like ours today." If correct, this means that the belief that the modern human hand is the result of more recent changes necessary for stone tool-making is incorrect.

The study is published in the latest issue of the on-line journal Nature Communications, part of the same group that publishes the prestigious science journal Nature.

Source: The evolution of human and ape hand proportions

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.

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The entire study can be read here: http://www.nature.com/ncomms/2015/15...comms8717.html