What is the historical context for why most people of African descent have a genetic mixture of different ancestries?

Transcript

When we think of Black people in the Americas who are descendants of people who were enslaved during the Transatlantic Slave Trade, we should understand that during every generation, the different groups in Americas came together to have children, however it happened.

When we think of the Americas and the history of the Americas, it's understood that the first people were the Indigenous people. So Indigenous Americans and their genetic ancestry at this point in American history is 100% Indigenous.

Then in 1492, the first documented Europeans came, and these two groups had children. Now you have one group that is 100% Indigenous American, another group that is 100% European, and then another genetically distinct group that's 50% European and 50% Indigenous American. This is what we call "admixture".

In the 1600's, the first documented Africans arrived in America. In the Caribbean, they came in the early 1500's. And so now we have, in addition to groups with European and Indigenous admixture, we now also have groups with indigenous and African admixture, a group with African and European admixture, and a small group that has admixture with all three groups represented by the small space where all three circles overlap.

The science doesn't support when Black people say things like, I have some Native American or some "Indian" in my family.

When we look at genetic ancestry studies, we see that the average genetic ancestry proportions for African-Americans are ~78% African, ~18% European and ~4% indigenous American.