Population inference from contemporary American craniometrics

Abstract

Population inference methods that allow for the model-bound estimation of admixture and ancestry proportions from craniometric data not only enable parallel-skeletal and genetic-analyses but they are also shown to be more informative than those methods that perform hard classifications using externally-imposed categories or seek to explain gross variation by low-dimensional projections. Am J Phys Anthropol 160:604-624, 2016. © 2016 Wiley Periodicals, Inc.

Understanding (Mis)classification Trends of Latin Americans in Fordisc 3.1: Incorporating Cranial Morphology, Microgeographic Origin, and Admixture Proportions for Interpretation

“…To determine whether there exists a relationship between the nature of the FD3 misclassifications (the reference groups to which targets are assigned) and individual levels of continental—African, European, and Indigenous American—ancestry, we generated for all PCOME test samples their relative proportions, or percent, of African, European, and Indigenous American ancestry. These estimates were derived from traditional cranial measurement data following the procedures already described by Algee‐Hewitt for the inference of continental ancestry and the quantification of admixture among contemporary individuals of United States and Latin American origins at various geographic (country‐wide, regional, and state) scales. We applied the unsupervised model‐based clustering methods of finite mixture analysis to a matrix of 20 craniofacial shape measures for a sample of 2277 individuals.…”

“…We applied the unsupervised model‐based clustering methods of finite mixture analysis to a matrix of 20 craniofacial shape measures for a sample of 2277 individuals. This large, mixed‐sex and multipopulation sample was formed from the combination of (i) the PCOME test cases described above and (ii) the subset of forensic and skeletal research cases from the Forensic Data Bank (FDB) reported in previous studies by Algee‐Hewitt . These FDB cases represent individuals of self‐reported or ascribed Black, Hispanic, Native American, or White identity.…”

“…Previous analyses of this FDB sample alone, and when combined with parental population samples drawn from the Sub‐Saharan African, European, and Indigenous American cranial series from the Howells dataset, have consistently produced three‐cluster solutions that correspond directly to a continental—African, European, and Indigenous American—ancestry model . While our FD3 classification and CV analyses both allowed for the possibility of Asian identity for the unknown targets and included Asian populations as part of the reference samples, we have chosen to exclude Asian cases here, limiting our analysis to an African, European, and American continental ancestry model.…”

“…While our FD3 classification and CV analyses both allowed for the possibility of Asian identity for the unknown targets and included Asian populations as part of the reference samples, we have chosen to exclude Asian cases here, limiting our analysis to an African, European, and American continental ancestry model. We argue that this continental model is appropriate because (i) it is commonly used in the genetic analysis of peoples of Latin American origin, including individuals from Mexico and (ii) Algee‐Hewitt found that, when the model‐based clustering analysis of the FDB sampled was expanded to include individuals of Asian identity, a three‐cluster model persisted. The Asian cases were consistently clustered with the Native Americans, producing a single grouping of individuals of recent and evolutionary Asian descent.…”

“…The study of morphological variation in the cranium is a cornerstone of skeletal population analyses, with standard interlandmark distance (ILD) measurements, that is, traditional craniometric data, providing adequate information for revealing population structure and, in turn, speaking to population histories at various levels of specificity . In terms of their information on biogeographic ancestry, craniometrics can capture both broad continental variation that may reflect our evolutionary history, and the more nuanced regional variation that may signal recent micro‐evolutionary processes, such as admixture events .…”