Human upper body evolution in the Eurasian later Pleistocene.

摘要

Analysis of upper body (thorax and upper limb) remains of fossil and Recent human skeletal samples was conducted to evaluate two broad perspectives on late archaic (Neandertal) versus modern human morphological contrasts in upper limb robusticity, muscularity, joint shapes and orientations, long bone diaphyseal shape and mechanical lever arm/load arm relationships. Osteometric and humeral cross sectional data were collected from samples of Neandertals, Levantine early modern humans, European Early and Late Upper Paleolithic associated modern humans, and Recent modern humans (archeological and documented samples of Euroamericans, Afroamericans, Aleuts, Pueblo Amerindians and Peruvian high-altitude populations). Exploratory and confirmatory factor analysis, as well as univariate testing, were used to test the competing ideas that (1) morphological contrasts between groups merely reflect skeletal changes correlated with changes in overall body form (size, chest shape, robusticity and limb proportions) in a tightly integrated, functional system, versus (2) they reflect significant differences between Neandertals and early anatomically modern humans in both activity levels and behavior patterns.; The results of the confirmatory factor analysis, along with the univariate testing and exploratory factor analysis of muscularity and robusticity variables, does not support the idea that general evolution in body form accounts for the observed upper limb morphological differences between groups. There does appear to be a limited degree of concerted ("vectored") temporal reduction in all measures of upper limb robusticity from fossil to Recent humans, but this trend alone is insufficient to account for the overall observed differences in upper limb morphology between groups. In addition, based on group means of robusticity factor scores, the real difference between groups on this robusticity vector lies between Upper Paleolithic associated modern humans and (highly variable) Recent human groups, not between the Neandertals and early anatomically modern humans.; The idea that morphological contrasts reflect behavioral contrasts could not be rejected. Upper body morphological differences between groups (both fossil and Recent human groups) likely reflect the action of bony remodeling and site-specific selection overlaid atop a basic Homo sapiens upper body plan. Thus the continued use of single traits or functional trait complexes in phylogenetic and functional analyses appears warranted.