On the number of genealogical ancestors tracing to the source groups of an admixed population.

The article investigates the number of genealogical ancestors from source populations in admixed individuals, focusing on African-Americans whose ancestry derives primarily from African and European sources. Using a mechanistic three-epoch admixture model informed by demographic and genetic data spanning 1619 to 1965, the study estimates that a random African-American born between 1960 and 1965 has on average about 314 African and 51 European genealogical ancestors. These ancestors predominantly trace to generations in the early 1700s, with a high probability that at least one European ancestor was born after 1835. The findings provide quantitative insight into the admixture process underlying African-American genealogies, reflecting historical events such as the Transatlantic Slave Trade and subsequent European admixture, while acknowledging model assumptions and limitations including fixed generation times, exclusion of Native American ancestry, and potential ancestor overlap in pedigrees.