Skull and limb morphology differentially track population history and environmental factors in the transition to agriculture in Europe

Abstract

The Neolithic transition in Europe was a complex mosaic spatio-temporal process, involving both demic diffusion from the Near East and the cultural adoption of farming practices by indigenous hunter-gatherers. Previous analyses of Mesolithic hunter-gatherers and Early Neolithic farmers suggest that cranial shape variation preserves the population history signature of the Neolithic transition. However, the extent to which these same demographic processes are discernible in the postcranium is poorly understood. Here, for the first time, crania and postcranial elements from the same 11 prehistoric populations are analysed together in an internally consistent theoretical and methodological framework. Results show that while cranial shape reflects the population history differences between Mesolithic and Neolithic lineages, relative limb dimensions exhibit significant congruence with environmental variables such as latitude and temperature, even after controlling for geography and time. Also, overall limb size is found to be consistently larger in hunter-gatherers than farmers, suggesting a reduction in size related to factors other than thermoregulatory adaptation. Therefore, our results suggest that relative limb dimensions are not tracking the same demographic population history as the cranium, and point to the strong influence of climatic, dietary and behavioural factors in determining limb morphology, irrespective of underlying neutral demographic processes.

Keywords: agricultural transition; cranium; natural selection; plasticity; population history; postcranium.

Figure 1.

Geographical distribution of 11 OTUs employed. Circles, Epipalaeolithic; triangles, Mesolithic; squares, Neolithic OTUs. Stars are way-points (Cairo, Istanbul and Venice) used to constrain pairwise geographical distances (km) between the OTUs.