Caribbean and Organization of American States African Diaspora Affairs

Autosomal genetic studies and the African contribution to Brazil

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Afro-Brazilians celebrating at a ceremony held by the Ministry of Culture.

African ancestry has contributed to the formation of Brazil, along with European and Amerindian ancestries.

A 2015 autosomal genetic study, which also analysed data of 25 studies of 38 different Brazilian populations concluded that: European ancestry accounts for 62% of the heritage of the population, followed by the African (21%) and the Native American (17%). The European contribution is highest in Southern Brazil (77%), the African highest in Northeast Brazil (27%) and the Native American is the highest in Northern Brazil (32%).[83]

Region[83] European African Amerindian
North Region 51% 16% 32%
Northeast Region 58% 27% 15%
Central-West Region 64% 24% 12%
Southeast Region 67% 23% 10%
South Region 77% 12% 11%

An autosomal study from 2013, with nearly 1300 samples from all of the Brazilian regions, found a pedigree of European ancestry combined with African and Native American contributions. “Following an increasing North to South gradient, European ancestry was the most prevalent in all urban populations (with values up to 74%). The populations in the North consisted of a significant proportion of Native American ancestry that was about two times higher than the African contribution. Conversely, in the Northeast, Center-West and Southeast, African ancestry was the second most prevalent. At an intrapopulation level, all urban populations were highly mixed, stemming from the large mixed ancestry population rather than a heterogenous distribution of groups of individuals with single ethnic ancestry. ”

Region European African Amerindian
North Region 51% 17% 32%
Northeast Region 56% 28% 16%
Central-West Region 58% 26% 16%
Southeast Region 61% 27% 12%
South Region 74% 15% 11%

A 2011 autosomal DNA study, with nearly 1000 samples from all over the country (“whites”, “pardos” and “blacks”), found out a major European contribution, followed by a high African contribution and an important Native American component.[85] “In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South”.[85] The 2011 autosomal study samples came from blood donors (the lowest classes constitute the great majority of blood donors in Brazil [86]), and also public health institutions personnel and health students. The study showed that Brazilians from different regions are more homogenous than previously thought by some based on the census alone. “Brazilian homogeneity is, therefore, a lot greater between Brazilian regions than within Brazilians region”.[87]

Region[85] European African Amerindian
Northern Brazil 69% 11% 19%
Northeast of Brazil 60% 29% 9%
Southeast Brazil 74% 17% 7%
Southern Brazil 80% 10% 9%

According to an autosomal DNA study from 2010, “a new portrayal of each ethnicity contribution to the DNA of Brazilians, obtained with samples from the five regions of the country, has indicated that, on average, European ancestors are responsible for nearly 80% of the genetic heritage of the population. The variation between the regions is small, with the possible exception of the South, where the European contribution reaches nearly 90%.

The results, published by the scientific magazine American Journal of Human Biology by a team of the Catholic University of Brasília, show that, in Brazil, physical indicators such as skin colour, colour of the eyes and colour of the hair have little to do with the genetic ancestry of each person, which has been shown in previous studies (regardless of census classification). “Ancestry informative SNPs can be useful to estimate individual and population biogeographical ancestry. Brazilian population is characterized by a genetic background of three parental populations (European, African, and Brazilian Native Amerindians) with a wide degree and diverse patterns of admixture.

In this work we analyzed the information content of 28 ancestry-informative SNPs into multiplexed panels using three parental population sources (African, Amerindian, and European) to infer the genetic admixture in an urban sample of the five Brazilian geopolitical regions. The SNPs assigned apart the parental populations from each other and thus can be applied for ancestry estimation in a three hybrid admixed population.

Data was used to infer genetic ancestry in Brazilians with an admixture model. Pairwise estimates of F(st) among the five Brazilian geopolitical regions suggested little genetic differentiation only between the South and the remaining regions. Estimates of ancestry results are consistent with the heterogeneous genetic profile of Brazilian population, with a major contribution of European ancestry (0.771) followed by African (0.143) and Amerindian contributions (0.085).

The described multiplexed SNP panels can be useful tool for bioanthropological studies but it can be mainly valuable to control for spurious results in genetic association studies in admixed populations”.[89] It is important to note that “the samples came from free of charge paternity test takers, thus as the researchers made it explicit: “the paternity tests were free of charge, the population samples involved people of variable socioeconomic strata, although likely to be leaning slightly towards the “pardo” group”.[89]

Region[89] European African Amerindian
North Region 71% 18% 11%
Northeast Region 77% 14% 9%
Central-West Region 66% 19% 12%
Southeast Region 80% 14% 6%
South Region 88% 8% 5%

An autosomal DNA study from 2009 found a similar profile “all the Brazilian samples (regions) lie more closely to the European group than to the African populations or to the Mestizos from Mexico”.[90]

Region[91] European African Amerindian
North Region 61% 21% 18%
Northeast Region 67% 23% 10%
Central-West Region 66% 22% 12%
Southeast Region 61% 32% 7%
South Region 82% 9% 9%

According to another autosomal DNA study from 2008, by the University of Brasília (UnB), European ancestry dominates in the whole of Brazil (in all regions), accounting for 66% of the heritage of the population, followed by the African contribution (25%) and the Native American (9%).

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