ScienceDaily (Jan. 8, 2010) — Fossils may provide tantalizing clues to human history but they also lack some vital information, such as revealing which pieces of human DNA have been favored by evolution because they confer beneficial traits -- resistance to infection or the ability to digest milk, for example. These signs can only be revealed through genetic studies of modern humans and other related species, though the task has proven difficult.
Researchers have developed a new method for pinpointing pieces of human DNA have been favored by evolution within the human genome. The technique offers greater precision and resolution than ever before. (Credit: iStockphoto)
Now, in a paper appearing in the January 7 edition of Science Express, researchers describe a method for pinpointing these preferred regions within the human genome that offers greater precision and resolution than ever before, and the possibility of deeply understanding both our genetic past and present.
"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," said senior author Pardis Sabeti, an associate member of the Broad Institute of Harvard and MIT and an assistant professor of organismic and evolutionary biology at Harvard University. "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."
Positive natural selection is a process in which advantageous traits become more common in a population. That is because these traits boost an individual's chances of survival and reproduction, so they are readily passed on to future generations. Identifying such traits -- and the genes underlying them -- is a cornerstone of current efforts to dissect the biological history of the human species as well as the diseases that threaten human health today.
"In the human genome, positive natural selection leaves behind very distinctive signals," said co-first author Sharon Grossman, a research assistant at Harvard University and the Broad Institute. Yet earlier methods for detecting these signals are limited, highlighting relatively large chunks of the genome that are hundreds of thousands to millions of genetic letters or "bases" in length, and that can contain many genes.
Of the hundreds of these large genomic regions thought to be under positive natural selection in humans, only a handful have so far been winnowed to a precise genetic change. "Finding the specific genetic changes that are under selection can be like looking for a needle in a haystack," said Grossman.
...
Read more here/Leia mais aqui.
+++++
Journal Reference:
Grossman et al. A composite of multiple signals distinguishes causal variants in regions of positive selection. Science, 2010 DOI: 10.1126/science.1183863
+++++
Professores, pesquisadores e alunos de universidades públicas e privadas com acesso ao site CAPES/Periódicos podem ler gratuitamente este artigo da Science e de mais 15.000 publicações científicas.
