The extent to which colonizing farmer populations have overwhelmed or "replaced" indigenous forager populations, as opposed to having intermarried with them, has been widely debated. Indigenous-colonist "admixture" is often represented in genetic models as a single parameter that, although parsimonious and simple, is incongruous with the sex-specifi c nature of mtDNA and Y-chromosome data. To help interpret genetic patterns, we can construct useful null hypotheses about the generalized migration history of females (mtDNA) as opposed to males (Y chromosome), which differ signifi cantly in almost every ethnographically known society. We seek to integrate ethnographic knowledge into models that incorporate new social parameters for predicting geographic patterns in mtDNA and Y-chromosome distributions. We provide an example of a model simulation for the spread of agriculture in which this individual-scale evidence is used to refine the parameters. Abstract The extent to which colonizing farmer populations have overwhelmed or "replaced" indigenous forager populations, as opposed to having intermarried with them, has been widely debated. Indigenous-colonist "admixture" is often represented in genetic models as a single parameter that, although parsimonious and simple, is incongruous with the sex-specifi c nature of mtDNA and Y-chromosome data. To help interpret genetic patterns, we can construct useful null hypotheses about the generalized migration history of females (mtDNA) as opposed to males (Y chromosome), which differ significantly in almost every ethnographically known society. We seek to integrate ethnographic knowledge into models that incorporate new social parameters for predicting geographic patterns in mtDNA and Y-chromosome distributions.We provide an example of a model simulation for the spread of agriculture in which this individual-scale evidence is used to refi ne the parameters.Understanding the processes through which populations grow and disperse is crucial to the study of human history and diversity and forms a major topic in anthropology and other related disciplines. A key problem is determining the extent to which colonizing populations (e.g., modern humans, Neolithic farmers, European colonists) overwhelmed or "replaced" native populations (e.g., Neanderthals, hunter-gatherers, non-European indigenous societies), as opposed to having integrated into or intermarried with them. These issues have been debated by numerous researchers in a variety of different historical and regional contexts, but no consensus has yet been reached about whether or not it is possible to discern any general patterns. Here, we aim to contribute to a more sophisticated understanding of human migratory activity by integrating data drawn from several disciplines, namely, archaeology, ethnography, and human genetics. Our critique focuses on the highly infl uential wave of advance model of human dispersals, as fi rst developed by Ammerman and Cavalli-Sforza (1984). We argue that this model is not equipped to con...