The contribution of different ancestral populations to the genetic make-up of the people of the Americas is reported in Nature Communications this week. The research highlights the influence of the slave trade and other historical events on genetics in the Americas and reveals a previously unrecognised contribution from certain European and African populations.
In genetics, admixture is the result of migration and breeding of distant populations. Cristian Capelli and colleagues used a high-resolution ancestry identification approach on a large set of genetic data from a variety of American, European and African populations, to determine the admixture of contemporary populations of the Americas.
They found that Caribbean populations showed a higher African component than South American ones, which the authors note is consistent with historical evidence of larger numbers of enslaved people on Caribbean Islands. They also showed that the Yoruban population from West Africa was the largest African genetic contributor to all people in the Americas, appearing to confirm records that this region was a major source of slaves.
In terms of European genetic contribution the largest, for the nine Hispanic and Latin populations in the study, came from Spain. In contrast, Great Britain was the greatest contributor to the Afro-American and Barbadian populations. The authors also identified, for the first time, the genetic signature of Basque ancestry in five out of the six Continental South American populations in the study, possibly a result of immigration in the sixteenth and seventeenth centuries. They also found a considerable French contribution in one Afro-American sample and suggest that this is due to French immigration during colonial times.