terça-feira, 8 de março de 2011

É do sul da Africa que viemos

Em artigo publicado na edição da semana de 7 de Março de 2011 dos Proceedings of the National Academy of Sciences, um nova pesquisa fortalece a versão que os humanos modernos surgiram, evoluiram e disseminaram-se a partir de raízes plantadas no sul e não no leste do continente africano.  Aí está o Abstract desse artigo que tem a seguinte observação This Feature Article is part of a series identified by the Editorial Board as reporting findings of exceptional significance.

Hunter-gatherer genomic diversity suggests a southern African origin for modern humans.
Brenna M. Henna, Christopher R. Gignoux, Matthew Jobinc, Julie M. Granka, J. M. Macpherson, Jeffrey M. Kidd, Laura Rodríguez-Botigué, Sohini Ramachandran, Lawrence Hon, Abra Brisbin, Alice A. Lin, Peter A. Underhill, David Comas, Kenneth K. Kidd, Paul J. Norman, Peter Parham, Carlos D. Bustamante, Joanna L. Mountain, and Marcus W. Feldman

Africa is inferred to be the continent of origin for all modern human populations, but the details of human prehistory and evolution in Africa remain largely obscure owing to the complex histories of hundreds of distinct populations. We present data for more than 580,000 SNPs for several hunter-gatherer populations: the Hadza and Sandawe of Tanzania, and the ≠ Khomani Bushmen of South Africa, including speakers of the nearly extinct N|u language. We find that African hunter-gatherer populations today remain highly differentiated, encompassing major components of variation that are not found in other African populations. Hunter-gatherer populations also tend to have the lowest levels of genome-wide linkage disequilibrium among 27 African populations. We analyzed geographic patterns of linkage disequilibrium and population differentiation, as measured by FST, in Africa. The observed patterns are consistent with an origin of modern humans in southern Africa rather than eastern Africa, as is generally assumed. Additionally, genetic variation in African hunter-gatherer populations has been significantly affected by interaction with farmers and herders over the past 5,000 y, through both severe population bottlenecks and sex-biased migration. However, African hunter-gatherer populations continue to maintain the highest levels of genetic diversity in the world.

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