Libby Cowgill:
Long Bone Growth in Immature Late Pleistocene Hominids
Studies of adult fossil remains have identified several consistent trends in postcranial robusticity that vary both temporally and spatially across the Late Pleistocene. These analyses have highlighted biobehavioral contrasts and similarities among Neandertals, early modern humans, and recent human populations. Specific differences in postcranial anatomy among these three groups likely result from multiple factors, including genetic differences, body proportions, manipulative behavior, mobility, and ontogenetic history.
Little research, however, has focused on the ontogeny of postcranial strength, leaving several critical questions unanswered: h ow do different populations come to vary in their degree of long bone strength? Are the differences seen in adult populations partially a reflection of activities prior to adulthood? When during growth do populational differences in bone strength emerge? Do all populations attain bone strength in the same pattern and at the same rate?
My research focuses on addressing these questions through the examination of the cross-sectional properties of immature Late Pleistocene and recent human postcrania. The foundation of this research involves establishing the range of variation in the developmental acquisition of postcranial strength in a large, geographically diverse sample of immature recent human femora, tibiae, and humeri. This sample, containing over 800 individuals from eight different populations, derives from European, American, and African skeletal collections, and serves as a baseline against which Late Pleistocene postcranial growth can be contrasted. Within this comparative framework, cross-sectional geometry will be used to evaluate levels of relative postcranial robusticity, differences in diaphyseal shape, and potential heterochronic shifts in the rate of growth in Late Pleistocene subadults, in relation to the sample of recent humans.
By contrasting the ontogenetic trajectories of postcranial growth in these three groups, I hope to both clarify the developmental basis for the acquisition of adult postcranial strength in Neandertals and early modern humans, and to contribute an ontogenetic perspective to previously assessed differences in Late Pleistocene adult postcranial morphology. Ultimately, this analysis will provide insight into the complex mosaic of factors that result in adult postcranial robusticity and morphology in recent and Late Pleistocene populations.
This research is supported by the National Science Foundation, the Leakey Foundation, and the Wenner-Gren Foundation.