Craniofacial morphology, diet and incisor use in three native American populations

Abstract

It has been difficult to infer behaviours related to anterior tooth use in fossil hominids owing to a lack of broad-based comparative studies of the relationships between front tooth use and craniodental features in modern humans. In this study, we seek to establish such a neontological baseline by exploring aspects of craniodental form among populations of recent humans that are inferred to have differed in habitual levels of ingestive and paramasticatory processing using the incisors. Morphometric data are compared among samples from three human populations: Aleutian Islanders (n=25); Arikara from the Mobridge Site, SD (n=19); and a late Woodland Bluff group from Jersey County, IL (n=24). Data for various biomechanically relevant dimensions were collected using standard callipers, while three-dimensional (3D) coordinate data for 28 cranial landmarks were recorded using a video-based image analysis system. These data indicate that several aspects of cranial form thought to influence the efficiency of force production on the incisors differ among the examined groups, including the positions and size of the primary masticatory muscles and the position of the dentition. For most dimensions, the Aleut sample exhibits the most mechanically advantageous configuration, the Illinois Bluff group the least advantageous configuration, while the Arikara are intermediate in form. This pattern corresponds to differences in the intensity of incisor loading among these groups, as inferred from both ethnographic reports and incisor microwear data. These results, therefore, suggest that cranial form in humans varies with subsistence-related differences in masticatory force production and that quantitative studies of masticatory system configuration may provide useful information for studies of hominid palaeobiology. Copyright © 2000 John Wiley & Sons, Ltd.