African American DNA Research Forum
DNA Tribes' Explanation of South African Matches
Thank you for your feedback. Our analysis statistically measures each person's genetic connections to various ethnic groups and major geographical regions. While population matches indicate a strong genetic relanship with a nation or ethnicity, they don't necessarily require membership in that group. Many of these connections are preserved from genetic contact or common origins hundreds or thousands of years ago. A genetic match with the Zulu population indicates you share strong genetic ties with this group of people as they exist now.
A trickier question is whether a person's ancestors were of a certain religious, ethnic, or language group. Unfortunately, genes cannot directly show this, because all groups tend to change over time. For instnace, the ancestors of the Zulu 500 years ago might have been different from the Zulu of today, for various reasons.
Linguists believe that the Bantu-speaking peoples of Africa, including the Zulu, Xhosa, and many others, share ancestors that spread from West Africa in the second millenium BC. As they expanded throughout Africa, some of these groups seem to have absorbed linguistic (and likely genetic) traits from the Khoisan-speakings peoples of southern Africa (such as the Xhosa). So modern Xhosa likely share genetic ancestry from both West Africa and Southern Africa. Some of this West African ancestry might be more specific than what can now be found in urban West African populations.
So when a person matches the Xhosa, they might be matching a specific West African component that survives in the Xhosa in a more concentrated form than in a more modern Equatorial Guinea of recently blended ancestries.
The best way to untangle this type of complex but fascinating genetic relationship is with an expanded dataset. Ideally, we will someday have population data not just for all parts of Africa, but representing the full diversity of African ethnicities, many of whom retain unique genetic characteristics. The new South African populations are a step in the right direction; we hope to eventually follow up with many more ethnic-specific populations.