Morphometric analysis of shape differences in Windover and Point Hope archaic human mandibles

Abstract

ObjectivesThe mandible can provide valuable information on both the life history and genetic makeup of Archaic human populations. The following analysis tests two hypotheses: (a) that there are significant differences in morphology in mandibular shape between the genders amongst Archaic North American Homo sapiens and (b) that there is a significant difference in variance in mandibular shape between Archaic Windover and Point Hope.Materials and MethodsA sample made from mandible specimens taken from both populations is subjected to Principal Component Analyses (PCA). The component scores from the PCAs are subjected to both a Multivariate Analysis of Covariance (mancova) and a general Multivariate Analysis of Variance (manova) to determine whether significant differences in variance exist between the sexes and the populations.ResultsThe mancova found that there are no significant interactions between the PC scores in population, sex, or size. Significant differences in variance were found between males and females and between the Windover and Point Hope populations.ConclusionsDifferences in variance observed between the populations are suspected to be due to differences in subsistence strategies and possibly non‐masticatory utilizations of teeth. Differences in variance between the genders are suspected to be genetic in origin.

A three-dimensional statistical shape model of the growing mandible

“…Cross-sectional studies that have investigated the shape of the mandible often suffer from the same limitations 26,36,39 . There are several reports on the natural variation in morphology of the mandible, but these pertain to the adult mandible only [20][21][22][23][24][25] 33,34,40 , and have the most comparable data sets to the current study. Of the research with a similar age range as the present study, four studies employ PCA to investigate the morphology of the mandible 27,[33][34][35] .…”

“…Some studies investigated one aspect of the mandible, such as the condyle 10-13 , ramus 14 , mandibular canal [15][16][17][18] , or the lingula 16,19 . Several authors attempted to describe the shape [20][21][22][23][24][25] or the growth of the mandible as a whole [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] . Limitations of these studies mainly involve a small sample size, narrow age range, selection bias, or extensive manual input, such as landmark annotation.…”