Morphological Integration of the Modern Human Mandible during Ontogeny

Joshua M Polanski

doi:10.4061/2011/545879

Abstract

Craniofacial integration is prevalent in anatomical modernity research. Little investigation has been done on mandibular integration. Integration patterns were quantified in a longitudinal modern human sample of mandibles. This integration pattern is one of modularization between the alveolar and muscle attachment regions, but with age-specific differences. The ascending ramus and nonalveolar portions of the corpus remain integrated throughout ontogeny. The alveolar region is dynamic, becoming modularized according to the needs of the mandible at a particular developmental stage. Early in ontogeny, this modularity reflects the need for space for the developing dentition; later, modularity is more reflective of mastication. The overall pattern of modern human mandibular integration follows the integration pattern seen in other mammals, including chimpanzees. Given the differences in craniofacial integration patterns between humans and chimpanzees, but the similarities in mandibular integration, it is likely that the mandible has played the more passive role in hominin skull evolution.

Highlights

Morphological integration of the cranium has become a dominant research paradigm in biological anthropology. While it began with the early work of Weidenreich [1, 2] and the functional matrix model of Moss [3, 4], morphological integration became a driving force in anthropological research through work on macaques and New World monkeys by Cheverud and colleagues [5,6,7,8,9,10,11]
Before detailing differences and similarities in the patterns of integration between the three developmental groups, it is advantageous to compare the overall level of integration between juvenile, adolescent, and adult modern human
Puberty is marked by a sudden increase in the amount of modularity in the mandible, which may be the result of a need to increase the adaptability of this region during a time of rapid facial growth

Summary

Introduction

Morphological integration of the cranium has become a dominant research paradigm in biological anthropology. While it began with the early work of Weidenreich [1, 2] and the functional matrix model of Moss [3, 4], morphological integration became a driving force in anthropological research through work on macaques and New World monkeys by Cheverud and colleagues [5,6,7,8,9,10,11] Building upon this earlier work, recent years have seen new techniques defined to quantify and assessing morphological integration being used to address the question of hominin evolution, with a particular emphasis on the evolution of modern humans [12,13,14,15,16,17,18,19]. At one time or another, as type specimens for various hominin species: Australopithecus anamensis [20]; A. afarensis [21]; A. bahrelghazali [22]; Paranthropus crassidens [23]; Homo ergaster [24]; H. heidelbergensis [25]

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Results

Discussion

Conclusion