Sexual Dimorphism and Population Affinity in the Human Zygomatic StructureComparing Surface to Outline Data

The human zygomatic structure, consisting of the zygomatic bone and the zygomatic process of the temporal bone, is an essential part of the masticatory apparatus and has been shown to reflect population history and sexual dimorphism to varying degrees. In this study, we analyzed the predictive value of the outlines vs. the complete surface shape of the zygomatic bone in a sample of 98 Chinese (50 f, 48 o) and 96 Germans (49 f, 47 o). We first applied a surface registration process based on statistical shape modeling. A dense set of 1,480 pseudo-landmarks was then sampled automatically from the surface of the pooled mean shape and three curves were digitized manually along the outlines of the zygomatic bone. Both sets of pseudo-landmarks were automatically transferred to all specimens. Analysis of sex and population affinity showed both factors to be independently significant, but the interaction between them was not. Population affinity could be predicted quite accurately with correct classification of 97.9% using the surface data and 93.3% with the curve data. Sexual dimorphism was less distinct with 89.2% correct sex determination when using surface information compared with 77.8% when using the curve data. Population-related shape differences were captured primarily in the outlines, while sexual dimorphism is distributed more uniformly throughout the entire surface of the zygomatic structure. Anat Rec, 300:226-237, 2017. (c) 2016 Wiley Periodicals, Inc.