Lower limb length of European early modern humans in relation to mobility and climate

There are two competing hypotheses to explain the relatively long lower limbs of the earliest modern Europeans. The first follows from Allen's (1877) rule and posits that the long legs are indicative of gene flow from warmer regions at the time of the archaic/modern Homo sapiens transition. The second maintains that the long lower limbs are an adaptive response to selection for locomotor efficiency. This paper tests predictions derived from these two competing hypotheses using anthropometric, residential mobility and climatic data for a sample of 19 recent hunter-gatherer groups. For this sample, there is no relationship between relative lower limb length (as reflected in relative sitting height) and residential mobility. Consequently, the mobility hypothesis can be rejected. However, a significant relationship between climate and relative lower limb length could not be rejected. With regard to Later Pleistocene human evolution, these results are interpreted as evidence for significant gene flow from tropical regions associated with the first appearance of modern humans in Europe.