Publication Date

Summer 7-15-2019

Abstract

African American admixture has been a focal topic of genetic studies since the mid-20thcentury. Generally, these studies estimate individual- and population-level African and European ancestry proportions. Some of these studies fit unrealistic admixture models to the patterns of genetic diversity in African Americans to determine both the onset time of admixture between Africans and Europeans, and the per-generation contribution of Europeans.

This research has failed to consider the contribution of the millions of Africans who migrated, either forcibly or by choice, to North America during and after slave importation, and failed to consider how changing social dynamics have affected the interactions between people of African and European descent over the past 400 years. These social dynamics include forcible control of mating by slave owners, antebellum and post-Civil-War segregation, the Great Migration, and the Civil Rights Movement. In this research, I demonstrate how this oversight has clouded our understanding of the admixture process in African Americans, including the timing and degree of African and European contributions, and prevented us from exploring the effects of social processes on the interactions between human populations across human evolution.

I attempted to overcome these shortcomings using historical, genetic, and dental data to estimate the timing and degree of European and African contributions to African Americans in different regions of the US. First, I fit two models of admixture to genetic datasets that included African contribution. For these models, I used historical data to inform the per-generation African contribution, then compared the fit of these models to the unrealistic models used previously. Second, after determining that dental morphological data can be used for ancestry estimation, I evaluated geographic and temporal variation in African American ancestry using dental morphological characteristics, and addressed the possible causes of that variation.

Important conclusions about African American admixture from each of the three studies that I conducted for this thesis are: 1) admixture models that incorporate history about African Americans fit empirical ancestry distributions better than models that fail to account for this history, 2) the variation in ancestry across time and space is due to admixture and possibly drift.

Keywords

Admixture, African Americans, Ancestry, Dental Morphology, Ancestry Estimation, Gene Flow

Document Type

Dissertation

Language

English

Degree Name

Anthropology

Level of Degree

Doctoral

Department Name

Anthropology

First Committee Member (Chair)

Heather JH Edgar

Second Committee Member

Yann Klimentidis

Third Committee Member

Sherry Nelson

Fourth Committee Member

David Prior

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