Modeling Conditions Necessary to Detect Gene Flow in Humans from Archaeological Contexts

Summary

Gene flow between ancient human groups is difficult to detect. In a closed deme, variance in a morphological trait should decrease over short time periods due to genetic drift. Previous studies have thus regarded increases in within-site trait variance over time as a possible indicator for new genetic variation through flow or the physical movement of individuals. This interpretation depends on archaeological context, as diachronic changes in population variance may also arise from selection, sampling differences, or population structure changes. This study applies genetic cline theory to investigate limitations in modeling changes in trait variance due to flow over three time periods among multiple sites. We fit simulated data based on parameters obtained from archaeological dental metrics to models of genetic isolation and flow. The model for no gene flow is that trait means shift stochastically but do not change, and variances decrease over time. Departures from these conditions argue for gene flow. Changes in trait means occur when gene flow is asymmetric between groups with previously distinct trait means. We show that at least three sites from each temporal horizon are necessary to achieve an unambiguous model fit for gene flow among groups within and between time periods.

This Resource is Part of the Following Collections

• Society for American Archaeology 82nd Annual Meeting, Vancouver, BC (2017)

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Record Identifiers

Abstract Id(s): 17083