Dental analysis of Classic period population variability in the Maya area

by Scherer, Andrew Kenneth

Abstract (Summary)
In this dissertation I examine population history and structure in the Maya area during

the Classic period (A.D. 250-900). Within the Maya area, archaeologists have identified

regional variation in material culture between archaeological zones. These cultural differences

may correspond to biological differences between Classic Maya populations. I test the

hypothesis that Classic Maya population structure followed an isolation by distance model. I

collected dental nonmetric and metric traits on 977 skeletons, from 18 Classic period sites,

representing seven different archaeological zones. I corrected the data for intraobserver error.

For the dental nonmetric data, I developed a Maya-specific trait dichotomization scheme and

controlled for sex bias. I tested the dental metric data for normality and age affects. I imputed

missing dental metric data for some traits and the remaining set of traits was Q-mode

transformed to control for allometric factors. I analyzed the dental nonmetric and metric datasets

with both univariate and multivariate tests. I found, with a log likelihood ratio, that 50% of the

nonmetric traits exhibited statistically significant differences between Maya sites. I performed a

Mean Measure of Divergence analysis of the dental nonmetric dataset and found that majority of

the resulting pairwise distance values were significant. Using cluster analysis and

multidimensional scaling, I found that the dental nonmetric data do not support an isolation by

distance organization of Classic Maya population structure. In the ANOVA and MANOVA

tests, I did not find major statistically significant differences in dental metrics between Maya

sites. Using principal components analysis, a Mahalanobis Distance test, and R matrix analysis,

I found a generally similar patterning of the dental metric data. The dental metric data to not

support an isolation by distance model for Classic Maya population structure. However, the

geographically outlying sites from Kaminaljuyu and the Pacific Coast repeatedly plotted as

biological outliers. R matrix analysis indicates that gene flow, not genetic drift, dominated

Classic Maya population structure. Based on the results of the dental nonmetric and metric

analyses, I reject the hypothesis that isolation by distance is a valid model for Classic Maya

population structure. From the multivariate analyses of the dental nonmetric and metric data, a

few notable observations are made. The major sites of Tikal and Calakmul both demonstrate

substantial intrasite biological heterogeneity, with some affinity to other sites but with little to

one another. Piedras Negras demonstrates some evidence for genetic isolation from the other

lowland Maya sites. In the PasiĆ³n Zone, Seibal and Altar de Sacrificios demonstrate some

affinity to one another, though Dos Pilas is an outlier. The R matrix analysis found evidence of

Classic period immigration into Seibal from outside the network of sites tested. The Belize Zone

exhibited substantial heterogeneity among its sites, with the site of Colha showing some affinity

to the Central Zone. Copan, despite being a geographic outlier, demonstrates genetic affinity

with the rest of the Maya area. Kaminaljuyu and the Pacific Coast were both found to be

outliers. These results indicate that dental nonmetric and metric data are a useful tool for

investigating ancient biological variability in the Maya area and contribute to our expanding

understanding of population history in that region.

Bibliographical Information:

Advisor:Wright, Lori E.; Steele, D. Gentry; Carlson, David L.; Honeycutt, Rodney L.

School:Texas A&M University

School Location:USA - Texas

Source Type:Master's Thesis

Keywords:maya biological distance dental metrics nonmetrics bioarchaeology population history


Date of Publication:12/01/2004

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