Race science is pseudo-science.

I did wonder if they’d possibly done an isotope analysis at the same time, but nothing was mentioned.

same way we can map the origin of the human species to west africa: identifying unqiue dna sequences of local areas and correlating the data (e.g. if they’ve found a certain dna sequence in all humans that they’ve also found on bones from 100,000 years ago in west africa, then that could suggest all humans originated from west africa at least 100,000 years ago)