Two-step Process Filters Evolution of Genes of Human and Chimpanzee

Although the human and chimpanzee genomes are distinguished by 35 million differences in individual DNA "letters," only about 50,000 of those differences alter the sequences of proteins. Of those 50,000 differences, an estimated 5,000 may have adaptive consequences in the evolutionary divergence between these two species, according to a study published in the March 6, 2007, issue of the Proceedings of the National Academy of Sciences.