The research analysed the
mitochondrial DNA (mtDNA), which is present in all human beings and passed down with only minor mutations through the maternal line. The other is the
Y chromosome, which is present only in males and is passed down with only minor mutations through the paternal line. Both can show from what part of the world a matrilineal or patrilineal ancestor of a person came from, but one can have in mind that they are only a fraction of the human genome, and reading ancestry from Y chromosome and mtDNA only tells 1/23rd the story, since humans have 23 chromosome pairs in the cellular DNA. Analysing the Y chromosome, which comes from male ancestors through the paternal line, it was concluded that half (50%) of Brazilian "negros" Y chromosomes come from
Europe, 48% come from
Africa and 1.6% come from
Native Americans. Analysing their mitochondrial DNA, that comes from female ancestors though maternal line, 85% of them come from Africa, 12.5% come from Native Americans and 2.5% come from Europe. The high level of European ancestry in African Brazilians through paternal line exists because, for much of Brazil's history, there were more Caucasian males than Caucasian females. So inter-racial relationships between Caucasian males and African or Native American females were widespread. " (1895), by Galician painter
Modesto Brocos showing a Brazilian family each generation becoming "whiter". Over 75% of Caucasians from
North and
Northeastern Brazil would have over 10% African genes, according to this particular study. Even in
Southeastern and
Southern Brazil, regions which received large waves of European immigration beginning in the 1820s and growing strongly
in the late 19th century, 49% of the Caucasian population would have over 10% African genes, according to that study. Thus, 86% of Brazilians would have at least 10% of genes that came from Africa. The researchers however, were cautious about their conclusions: "Obviously these estimates were made by extrapolation of experimental results with relatively small samples and, therefore, their confidence limits are very ample". An autosomal study from 2011, also led by Sérgio Pena, but with nearly 1000 samples this time, from all over the country, shows that in most Brazilian regions most Brazilians "whites" are less than 10% African in ancestry, and it also shows that the "pardos" are predominantly European in ancestry, the European ancestry being therefore the main component in the Brazilian population, in spite of a very high degree of African ancestry and significant Native American contribution. Other autosomal studies show a European predominance in the Brazilian population. A 1981 study of blood polymorphisms examined 1,000 people from
Porto Alegre in Southern Brazil and 760 from
Natal in Northeastern Brazil. It found that people identified as White in Porto Alegre had 8% African ancestry, while those in Natal had a mix of 58% White, 25% Black, and 17% Amerindian ancestry. The study also showed that individuals identified as White or Pardo in Natal have a dominant European ancestry, while those identified as White in Porto Alegre have an overwhelming majority of European ancestry. According to an autosomal DNA genetic study from 2011, both "whites" and "pardos" from
Fortaleza have a predominant degree of European ancestry (>70%), with minor but important African and Native American contributions. "Whites" and "pardos" from
Belém and
Ilhéus also were found to be predominantly European in ancestry, with minor Native American and African contributions. According to another autosomal DNA study, those who identified as Whites in Rio de Janeiro turned out to have 86.4% – and self identified pardos 68.1% – European ancestry on average (autosomal).
Pretos were found out to have on average 41.8% European ancestry. public health personnel and health students. Brazilian homogeneity is, therefore, greater within regions than between them: A 2015 autosomal genetic study, which also analyzed 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 contribution is the highest in Northeast Brazil (27%) and the Native American contribution is the highest in Northern Brazil (32%). According to another study from 2008, by the University of Brasília, European ancestry dominates in the whole of Brazil in all regions, accounting for 65,90% of the heritage of the population, followed by the African contribution (24,80%) and the Native American (9,3%). According to an autosomal DNA study (from 2003) focused on the composition of the Brazilian population as a whole, "European contribution [...] is highest in the South (81% to 82%), and lowest in the North (68% to 71%). The African component is lowest in the South (11%), while the highest values are found in the Southeast (18%–20%). Extreme values for the Amerindian fraction were found in the South and Southeast (7%–8%) and North (17%–18%)". The researchers were cautious with the results as their samples came from paternity test takers which may have skewed the results partly. Several other older studies have suggested that European ancestry is the main component in all Brazilian regions. Salzano (1997) reported 51% European, 36% African, and 13% Amerindian ancestry for the Northeastern population. Santos and Guerreiro (1995) found 47% European, 12% African, and 41% Amerindian ancestry in the north. In the southernmost state of Rio Grande do Sul, Dornelles et al. (1999) calculated 82% European, 7% African, and 11% Amerindian ancestries. Krieger et al. (1965) studied a Northeastern Brazilian population living in São Paulo and found that whites had 18% African and 12% Amerindian genetic contribution, while blacks had 28% European and 5% Amerindian genetic contribution. These Amerindian estimates, like others, have limitations. Compared to earlier studies, the 2002 study findings showed higher levels of bidirectional admixture between Africans and non-Africans. In 2007
BBC Brasil launched the project
Raízes Afro-Brasileiras (Afro-Brazilian Roots), in which they analyzed the genetic ancestry of nine famous Brazilian blacks and "pardos". Three tests were based on analysis of different parts of their DNA: an examination of paternal ancestry, maternal ancestry and the genomic ancestry, allowing to estimate the percentage of African, European and Amerindian genes in the composition of an individual. Of the nine people analyzed, three had more European ancestry than African, while the other six people had more African ancestry, with varying degrees of European and Amerindian admixture. The African admixture varied from 19.5% in actress to 99.3% in singer
Milton Nascimento. The European admixture varied from 0.4% in Nascimento to 70% in Silva. The Amerindian admixture ranges from 0.3% in Nascimento to 25.4% in football player Obina. ==Media==