of the Niger-Congo (Niger-Kordofanian) family. Correspondingly, Montinaro et al. (2014) observed that around 50% of the overall ancestry of African Americans traces back to the Niger-Congo-speaking Yoruba of southwestern Nigeria and southern Benin, reflecting the centrality of this West African region in the Atlantic Slave Trade. The next most frequent ancestral component found among African Americans was derived from Great Britain, in keeping with historical records. It constitutes a little over 10% of their overall ancestry, and is most similar to the Northwest European ancestral component also carried by Barbadians. Zakharaia et al. (2009) found a similar proportion of Yoruba associated ancestry in their African American samples, with a minority also drawn from Mandenka and Bantu populations. Additionally, the researchers observed an average European ancestry of 21.9%, again with significant variation between individuals. Bryc et al. (2009) note that populations from other parts of the continent may also constitute adequate proxies for the ancestors of some African American individuals; namely, ancestral populations from Guinea Bissau, Senegal and Sierra Leone in West Africa and Angola in Southern Africa. Altogether, genetic studies suggest that African Americans are a genetically diverse people. According to DNA analysis led in 2006 by Penn State geneticist Mark D. Shriver, around 58 percent of African Americans have at least 12.5% European ancestry (equivalent to one European great-grandparent and his/her forebears), 19.6 percent of African Americans have at least 25% European ancestry (equivalent to one European grandparent and his/her forebears), and 1 percent of African Americans have at least 50% European ancestry (equivalent to one European parent and his/her forebears). According to Shriver, around 5 percent of African Americans also have at least 12.5% Native American ancestry (equivalent to one Native American great-grandparent and his/her forebears). Research suggests that Native American ancestry among people who identify as African American is a result of relationships that occurred soon after slave ships arrived in the American colonies, and European ancestry is of more recent origin, often from the decades before the Civil War. Y-DNA Africans bearing the E-V38 (E1b1a) likely traversed across the Sahara, from east to west, approximately 19,000 years ago. E-M2 (E1b1a1) likely originated in West Africa or Central Africa. According to a Y-DNA study by Sims et al. (2007), the majority (≈60%) of African Americans belong to various subclades of the E-M2 (E1b1a1, formerly E3a) paternal haplogroup. This is the most common genetic paternal lineage found today