The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)


A world-wide survey of humeral robusticity and midshaft shape

OSBJORN M. PEARSON1 and VITALE S. SPARACELLO2.

1Department of Anthropology, University of New Mexico, USA, 2Department of Archaeology, Durham University, UK

March 27, 2015 , Archview Ballroom Add to calendar

Although a widespread pattern of declining robusticity and decreasing antero-posterior (AP) reinforcement of diaphyses in the femur and tibia since the Early Upper Paleolithic (albeit with notable exceptions) is well-established, temporal or geographic trends in upper limb bones are less clear. To help address this problem, we present analyses of size-adjusted polar section moduli (Zp) and ratios of midshaft Imax/Imin for the humerus of Neandertals, Skhul-Qafzeh hominins, Gravettians, Magdalenians, Epigravettians, and 20 more recent samples, each subdivided by sex (total n = 985). Right humeri were used whenever possible. Second moments of area were predicted from external dimensions or periosteal contours of the midshaft sections. Size-adjusted Zp was calculated by dividing J by the half of the midshaft maximum diameter, then dividing by the product of humeral maximum length and body mass estimated from femoral head diameter. The results show no clear universal trend to decreasing or increasing humeral size-adjusted Zp. Patterns in Imax/Imin defy a simple over-arching explanation and are not significantly correlated with size-adjusted Zp. However, some interesting patterns emerged from the results: the females of each sample tend to have a lower mean value for size-adjusted Zp than males, male foragers and herders from cold climates (e.g., Inuit, Sami, Tierra del Fuego, and Mesolithic French and Danes) tend to have particularly high values of size-adjusted Zp; Neandertal males follow this pattern but Gravettian males do not. Male Australian aborigines also have a remarkably high mean for size-adjusted Zp.

We are grateful for funds in support of data collection from the National Science Foundation, Wenner-Gren Foundation, and the Boise Fund.