Changes in mandible characteristics during the terminal Pleistocene to Holocene Levant and their association with dietary habits

Abstract

The Levant is characterized by changes in human economic behavior and subsistence strategies, following the transition from a hunting and gathering society in terminal Pleistocene to a settled, agricultural society in the Holocene. Using an advanced approach previously recognized to be associated to some extent with masticatory system function, we aimed to examine the morphological changes in the mandible during these periods and determine whether they were associated with reduced demands of mastication force. Three major prehistoric populations of the Levant were studied: Natufian hunter-gatherers (n = 41), early farmers Pre-pottery Neolithic (n = 28), and Chalcolithic farmers (n = 13), samples of which are housed in the Anthropological collection at the Sackler Faculty of Medicine, TAU. A modern population was included as a control group (n = 61). Two types of measurements were carried out using CT scans of the mandibles: size measurements: 14 linear and cross-sectional area (CSA) measurements; and orientation measurements: four angular measurements. One Way ANOVA or Kruskal-Wallis tests were carried out to examine differences in measurements between the studied groups. Our results show a reduction in mandibular size during the last 15 thousand years, although some reduction occurred only after the Chalcolithic period. In addition, the mandibular body became positioned more upright and the mandibular angle increased. Some of the changes observed can be associated with mastication loadings. We therefore concluded that the ongoing reduced demand on the masticatory system during the Holocene was probably due to a softer diet, resulting in dramatic changes in the mandibular size and orientation. Moreover, we offer a set of measurement parameters that can be reliably used for the analyses of archaeological populations when studying dietary habits.