Dental analysis of Classic period population variability in the Maya area

Abstract

In this dissertation I examine population history and structure in the Maya area during \nthe Classic period (A.D. 250-900). Within the Maya area, archaeologists have identified \nregional variation in material culture between archaeological zones. These cultural differences \nmay correspond to biological differences between Classic Maya populations. I test the \nhypothesis that Classic Maya population structure followed an isolation by distance model. I \ncollected dental nonmetric and metric traits on 977 skeletons, from 18 Classic period sites, \nrepresenting seven different archaeological zones. I corrected the data for intraobserver error. \nFor the dental nonmetric data, I developed a Maya-specific trait dichotomization scheme and \ncontrolled for sex bias. I tested the dental metric data for normality and age affects. I imputed \nmissing dental metric data for some traits and the remaining set of traits was Q-mode \ntransformed to control for allometric factors. I analyzed the dental nonmetric and metric datasets \nwith both univariate and multivariate tests. I found, with a log likelihood ratio, that 50% of the \nnonmetric traits exhibited statistically significant differences between Maya sites. I performed a \nMean Measure of Divergence analysis of the dental nonmetric dataset and found that majority of \nthe resulting pairwise distance values were significant. Using cluster analysis and \nmultidimensional scaling, I found that the dental nonmetric data do not support an isolation by \ndistance organization of Classic Maya population structure. In the ANOVA and MANOVA \ntests, I did not find major statistically significant differences in dental metrics between Maya \nsites. Using principal components analysis, a Mahalanobis Distance test, and R matrix analysis, \nI found a generally similar patterning of the dental metric data. The dental metric data to not \nsupport an isolation by distance model for Classic Maya population structure. However, the \ngeographically outlying sites from Kaminaljuyu and the Pacific Coast repeatedly plotted as \nbiological outliers. R matrix analysis indicates that gene flow, not genetic drift, dominated \nClassic Maya population structure. Based on the results of the dental nonmetric and metric \nanalyses, I reject the hypothesis that isolation by distance is a valid model for Classic Maya \npopulation structure. From the multivariate analyses of the dental nonmetric and metric data, a \nfew notable observations are made. The major sites of Tikal and Calakmul both demonstrate \nsubstantial intrasite biological heterogeneity, with some affinity to other sites but with little to \none another. Piedras Negras demonstrates some evidence for genetic isolation from the other \nlowland Maya sites. In the Pasión Zone, Seibal and Altar de Sacrificios demonstrate some \naffinity to one another, though Dos Pilas is an outlier. The R matrix analysis found evidence of \nClassic period immigration into Seibal from outside the network of sites tested. The Belize Zone \nexhibited substantial heterogeneity among its sites, with the site of Colha showing some affinity \nto the Central Zone. Copan, despite being a geographic outlier, demonstrates genetic affinity \nwith the rest of the Maya area. Kaminaljuyu and the Pacific Coast were both found to be \noutliers. These results indicate that dental nonmetric and metric data are a useful tool for \ninvestigating ancient biological variability in the Maya area and contribute to our expanding \nunderstanding of population history in that region.

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