Background: Unraveling the ancestry of ‘Afro-American’ communities is hampered by the complex demographic
processes that took place during the Transatlantic Slave Trade (TAST) and the (post-)colonization periods. ‘AfroBolivians’
from the subtropical Yungas valleys constitute small and isolated communities that live surrounded by
the predominant Native American community of Bolivia. By genotyping >580,000 SNPs in two ‘Afro-Bolivians’, and
comparing these genomic profiles with data compiled from more than 57 African groups and other reference
ancestral populations (n = 1,161 in total), we aimed to disentangle the complex admixture processes undergone by
‘Afro-Bolivians’.
Results: The data indicate that these two genomes constitute a complex mosaic of ancestries that is approximately
80 % of recent African origin; the remaining ~20 % being European and Native American. West-Central Africa
contributed most of the African ancestry to ‘Afro-Bolivians’, and this component is related to populations living along
the Atlantic coast (i.e. Senegal, Ghana, Nigeria). Using tract length distribution of genomic segments attributable to
distinct ancestries, we could date the time of admixture in about 400 years ago. This time coincides with the maximum
importation of slaves to Bolivia to compensate the diminishing indigenous labor force needed for the development of
the National Mint of Potosí.
Conclusions: Overall, the data indicate that the genome of ‘Afro-Bolivians’ was shaped by a complex process of
admixture occurring in America among individuals originating in different West-Central African populations; their
genomic mosaics received additional contributions of Europeans and local Native Americans (e.g. Aymaras)The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program FP7/2007–2013/under REA grant agreement no. 290344, from the “Ministerio de Ciencia e Innovación” (SAF2011–26983), the “Plan Galego IDT” (EM 2012/045) and the grant from the “Sistema Universitario Gallego- Modalidad REDES (2012-PG226) from the Xunta de Galicia (A.S.). F.M-T received support from the grant “ISCIII/INT14/00245/ Cofinanciado FEDER"S
