Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. Export

@article{citeulike:5647661, abstract = {Despite decades of debate, it remains unclear whether human bipedalism evolved from a terrestrial knuckle-walking ancestor or from a more generalized, arboreal ape ancestor. Proponents of the knuckle-walking hypothesis focused on the wrist and hand to find morphological evidence of this behavior in the human fossil record. These studies, however, have not examined variation or development of purported knuckle-walking features in apes or other primates, data that are critical to resolution of this long-standing debate. Here we present novel data on the frequency and development of putative knuckle-walking features of the wrist in apes and monkeys. We use these data to test the hypothesis that all knuckle-walking apes share similar anatomical features and that these features can be used to reliably infer locomotor behavior in our extinct ancestors. Contrary to previous expectations, features long-assumed to indicate knuckle-walking behavior are not found in all African apes, show different developmental patterns across species, and are found in nonknuckle-walking primates as well. However, variation among African ape wrist morphology can be clearly explained if we accept the likely independent evolution of 2 fundamentally different biomechanical modes of knuckle-walking: an extended wrist posture in an arboreal environment (Pan) versus a neutral, columnar hand posture in a terrestrial environment (Gorilla). The presence of purported knuckle-walking features in the hominin wrist can thus be viewed as evidence of arboreality, not terrestriality, and provide evidence that human bipedalism evolved from a more arboreal ancestor occupying the ecological niche common to all living apes.}, author = {Kivell, Tracy L. and Schmitt, Daniel}, citeulike-article-id = {5647661}, citeulike-linkout-0 = {http://dx.doi.org/10.1073/pnas.0901280106}, citeulike-linkout-1 = {http://www.pnas.org/content/early/2009/08/06/0901280106.abstract}, citeulike-linkout-2 = {http://www.pnas.org/content/early/2009/08/06/0901280106.full.pdf}, citeulike-linkout-3 = {http://view.ncbi.nlm.nih.gov/pubmed/19667206}, citeulike-linkout-4 = {http://www.hubmed.org/display.cgi?uids=19667206}, day = {25}, doi = {10.1073/pnas.0901280106}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {200908, afrique, evolution, locomotion, paleontologie-humaine}, month = {August}, number = {34}, pages = {14241--14246}, posted-at = {2009-08-27 10:53:40}, priority = {2}, title = {Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor.}, url = {http://dx.doi.org/10.1073/pnas.0901280106}, volume = {106}, year = {2009} }

TY - JOUR ID - citeulike:5647661 L3 - citeulike-article-id:5647661 N2 - Despite decades of debate, it remains unclear whether human bipedalism evolved from a terrestrial knuckle-walking ancestor or from a more generalized, arboreal ape ancestor. Proponents of the knuckle-walking hypothesis focused on the wrist and hand to find morphological evidence of this behavior in the human fossil record. These studies, however, have not examined variation or development of purported knuckle-walking features in apes or other primates, data that are critical to resolution of this long-standing debate. Here we present novel data on the frequency and development of putative knuckle-walking features of the wrist in apes and monkeys. We use these data to test the hypothesis that all knuckle-walking apes share similar anatomical features and that these features can be used to reliably infer locomotor behavior in our extinct ancestors. Contrary to previous expectations, features long-assumed to indicate knuckle-walking behavior are not found in all African apes, show different developmental patterns across species, and are found in nonknuckle-walking primates as well. However, variation among African ape wrist morphology can be clearly explained if we accept the likely independent evolution of 2 fundamentally different biomechanical modes of knuckle-walking: an extended wrist posture in an arboreal environment (Pan) versus a neutral, columnar hand posture in a terrestrial environment (Gorilla). The presence of purported knuckle-walking features in the hominin wrist can thus be viewed as evidence of arboreality, not terrestriality, and provide evidence that human bipedalism evolved from a more arboreal ancestor occupying the ecological niche common to all living apes. IS - 34 JF - Proceedings of the National Academy of Sciences of the United States of America SN - 1091-6490 EP - 14246 TI - Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. VL - 106 SP - 14241 KW - 200908 KW - afrique KW - evolution KW - locomotion KW - paleontologie-humaine AU - Kivell, Tracy AU - Schmitt, Daniel PY - 2009/08/25/ UR - http://dx.doi.org/10.1073/pnas.0901280106 ER -