Masticatory function and post-Pleistocene evolution in Nubia.

The present research focuses on craniofacial variation in Nubia over approximately 10,000 years. Samples were grouped according to their temporal location and subsistence pattern, and represent a transition from a hunting-gathering adaptation (Mesolithic) to a transitional hunting-gathering-agricultural adaptation (A-C Group) and finally to a fully agricultural adaptation (Meroitic/X-Group/Christian). The purposes were: (1) to compare the Mesolithic sample with the later Nubian populations; and (2) to evaluate further the hypothesis that change in Nubian craniofacial morphology was due to changing functional demands associated with the progressive change in subsistence adaptation and associated behavior. The results tend to support recent views that the Nubian Mesolithic population is probably ancestral to later Nubian groups, and that the masticatory-functional hypothesis can best account for craniofacial change among the Nubians since 12,000 B.P. According to this hypothesis systematic reduction in functional demand placed on the masticatory complex from the Mesolithic led, secondarily, to an alteration of the growth of the maxillomandibular complex such that the face became progressively less robust and more inferoposteriorly located relative to the cranial vault. Both the increase in the height of the vault relative to its length, producing a more "globular" appearance, and the reduction in dental size were tertiary, compensatory responses to altered facial size and position.