01/08/2010 Erin Podolak
Researchers at the Broad Institute have developed a new technique to pinpoint the effects of natural selection by identifying specific genetic variations.
Darwin’s theory of natural selection, the process by which organisms evolve to feature certain favorable characteristics, may be 151 years old, but researchers from the Broad Institute of MIT and Harvard have just developed a method to measure the effects of natural selection in humans.“In the human genome, positive natural selection leaves behind very distinctive signals,” Sharon Grossman, co-first author and research assistant at Harvard University and the Broad Institute, said in a press release. Yet traditional methods for detecting variations in the human genome due to evolution could only suggest large sections of the genome as possible locations. At several thousand bases long, the sites contained multiple genes that could be expressing the traits favored by natural selection.
The new method, called composite of multiple signals (CMS), combines tests for multiple signals of selection to produce a single result, according to the Broad Institute researchers. Combining the genetic screening tests enabled the researchers to narrow the size of the candidate regions, from an average of eight genes per region to one specific gene.
“It’s clear that positive natural selection has been a critical force in shaping the human genome, but there are remarkably few examples that have been clearly identified,” Pardis Sabeti, associate member of the Broad Institute and an assistant professor of organismic and evolutionary biology at Harvard University, said in a press release. “The method we’ve developed makes it possible to zero in on individual genes as well as the specific changes within them that are driving important evolutionary changes.”
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NOTA IMPERTINENTE DESTE BLOGGER:
A Lógica Darwiniana 101 é uma das matérias mais difíceis de ser compreendida, até pelos especialistas, no tocante a declarações assim:
"It’s clear that positive natural selection has been a critical force in shaping the human genome, but there are remarkably few examples that have been clearly identified" [É claro que a seleção natural positiva tem sido uma força crítica em modelar o genoma humano, mas há extraordinariament poucos exemplos que foram nitidamente identificados].
Uai, se não existem dados robustos da seleção natural positiva agindo evolucionariamente, entonces, ché, como és possible quantificar el facto, Facto, FACTO de la evolución pela acción de la selección natural???
Quem sabe o ensaio A mal compreendida evolução publicado na Ciência Hoje 266, escrito pelos biólogos Rogério Parentoni Martins e Fabrício Rodrigues dos Santos, da UFMG, e por Francisco Ângelo Coutinho, educador da PUC-MG, discutindo as dificuldades que impedem a aceitação desse sistema, lance alguma luz sobre este assunto que gera dúvidas até mesmo entre os maiores estudiosos.
Cruz, credo, Darwin, não podia ser mais facinho, sô???
