Composition of Brazil, Genetic Studies
Genetic studies have shown the Brazilian population as a whole to have European, African and Native Americans components.
A recent autosomal DNA study (2011), 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. "In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South". The 2011 autosomal study samples came from blood donors (the lowest classes constitute the great majority of blood donors in Brazil), 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".
| Region | European | African | Native American |
|---|---|---|---|
| Northern Brazil | 68,80% | 10,50% | 18,50% |
| Northeast of Brazil | 60,10% | 29,30% | 8,90% |
| Southeast Brazil | 74,20% | 17,30% | 7,30% |
| Southern Brazil | 79,50% | 10,30% | 9,40% |
According to a 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". 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".
| Region | European | African | Native American |
|---|---|---|---|
| North Region | 71,10% | 18,20% | 10,70% |
| Northeast Region | 77,40% | 13,60% | 8,90% |
| Central-West Region | 65,90% | 18,70% | 11,80% |
| Southeast Region | 79,90% | 14,10% | 6,10% |
| South Region | 87,70% | 7,70% | 5,20% |
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".
| Region | European | African | Native American |
|---|---|---|---|
| North Region | 60,6% | 21,3% | 18,1% |
| Northeast Region | 66,7% | 23,3% | 10,0% |
| Central-West Region | 66,3% | 21,7% | 12,0% |
| Southeast Region | 60,7% | 32,0% | 7,3% |
| South Region | 81,5% | 9,3% | 9,2% |
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 65,90% of heritage of the population, followed by the African contribution (24,80%) and the Native American (9,3%).
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