by proldic » Sun Sep 04, 2005 8:01 pm
Science News 9/3/05<br><br>by Bruce Bower<br><br>Despite sharing much of their genetic identity with people, chimpanzees exhibit previously unappreciated DNA distinctions, according to the first rigorous comparisons of the two species' complete genetic sequences. <br><br>The new research "dramatically narrows the search for the key biological differences between the species,"...<br> <br>...an international consortium...analyzed the genetic sequence of a male common chimp and compared it with DNA data from people... <br> <br>...roughly 3 billion base pairs in the genomes of the two species have the same sequence 96 percent of the time. Even so, as many as <!--EZCODE BOLD START--><strong>3 million</strong><!--EZCODE BOLD END--> base pairs, or DNA building blocks, residing within protein-encoding and other functional areas of the genome differ between chimps and humans. <br><br>The new cross-species comparison identified six DNA segments in people that appear to have been strongly shaped by natural selection over just the past 250,000 years. <br><br>Gene functions in these regions are largely unknown... <br><br>...Chromosome ends served as "hot spots" for generating DNA disparities among primate species, the scientists propose. <br><br>Intriguingly, mutations on the chimp Y chromosome have led to the inactivation of several genes, but no comparable mutations exist on the human Y chromosome, report[s]...Massachusetts Institute of Technology... <br><br>In yet another finding...genes active in the brain have accumulated more changes in people than in chimps. Alterations of regulatory genes and protein-making genes have shaped human-brain evolution in equal measure, the scientists also conclude. <br><br>In related news, anthropologists have found in Kenya the first fossil of a chimp ancestor. The scientists unearthed three 500,000-year-old teeth that resemble those of common chimps today...<br><br>Fossils of a human ancestor, perhaps Homo erectus, come from the same ancient soil layer that the teeth did. Human and chimp ancestors apparently lived side by side, the [archeologists] concluded... <br><br><!--EZCODE AUTOLINK START--><a href="http://www.sciencenews.org/articles/20050903/fob1.asp">www.sciencenews.org/artic...3/fob1.asp</a><!--EZCODE AUTOLINK END--> <p></p><i></i>
