Admixture and ancestry inference from ancient and modern samples through measures of population genetic drift

Methods that leverage the information about population history contained within the increasingly abundant genetic sequences of extant and extinct hominid populations are diverse in form and versatile in application. Here, we review key methods recently developed to detect and quantify admixture and ancestry in modern human populations. We begin with an overview of the f- and D-statistics, covering their conceptual principles and important applications, as well as any extensions developed for them. We then cover a combination of more recent and more complex methods for admixture and ancestry inference, discussing tests for direct ancestry between two populations, quantification of admixture in large data sets, and determination of admixture dates. These methods have revolutionized our understanding of human population history and highlight its complexity. Therefore, we emphasize that current methods may not capture this population history in its entirety but nonetheless provide a reasonable picture that is supported by data from multiple methods and from the historical record.