75% of Caucasians from North and Northeastern Brazil would have over 10% native 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 nineteenth century, 49% of the Caucasian population would have over 10% native 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". A new 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 (see some of them below) show a European predominance in the Brazilian population. Another study (based on blood polymorphisms, from 1981) carried out in one thousand individuals from Porto Alegre city, Southern Brazil, and 760 from Natal city, Northeastern Brazil, found whites of Porto Alegre had 8% of African alleles and in Natal the ancestry of the samples total was characterized as 58% White, 25% Black, and 17% Amerindian". This study found that persons identified as White or Pardo in Natal have similar ancestries, a dominant European ancestry, while persons 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 study conducted at a school in the poor periphery of Rio de Janeiro, autosomal DNA study (from 2009), the "pardos" there were found to be on average over 80% European, and the "whites" (who thought of themselves as "very mixed") were found out to carry very little Amerindian and/or African admixtures.