Nasofacial skeletal divergence of admixed African-Americans away from Equatorial African morphology

Biological anthropologists have long highlighted nasofacial differences between African and European populations, often regarding African-Americans as morphological proxies for Equatorial Africans in these endeavors. Despite the known mid-facial skeletal morphology distinctions between Equatorial Africans and ancestral Europeans, little is known about how admixture between these two populations affects African-American nasofacial morphology. It has been argued that the nasofacial region of the cranium is under high genetic heritability. However, substantial amounts of ancestral European DNA are present in the African-American populations due to historical contact between these two ancestral populations. The extent in which African-American populations have diverged away from ancestral African mid-facial morphology expectations in a significant way due to this genetic admixture is largely unknown. Here, we evaluate the extent to which European admixture and genetic structure in African-Americans has resulted in nasofacial and genomic divergence from the ancestral Equatorial African form, thus impacting their utility as morphological proxies for Equatorial African populations. The results of this study will highlight the significant divergence of African-Americans away from Equatorial Africans in both their morphology and genetic structure. It will also highlight the potential for inaccurate conclusions when using this admixed population in skeletal and genomic research studies as proxies for their assumed ancestral counterparts. This study supports previously cited average values of genetic admixture in African-Americans while also showing extreme individual morphological and genetic divergence from assumed ancestral types.