By comparing the human genome with that of the chimpanzee, man’s closest living relative, researchers have discovered that chunks of similar DNA that have been flipped in orientation and reinserted into chromosomes are hundreds of times more common in primates than previously thought. These large structural changes in the genome, called inversions, may account for much of the evolutionary difference between the two species. They may also shed light on genetic changes that lead to human diseases.Although humans and chimpanzees diverged from one another genetically about six million years ago, the DNA sequences of the two species are approximately 98 percent identical. Given the 2005 publication of the draft chimpanzee genome sequence, researchers can now readily identify the differences between the human and chimp genomes. These differences lend insight into how primates evolved, including traits specific to humans. The researchers published their findings in the October 28, 2005, issue of the journal Public Library of Science Genetics (PLoS Genetics). The paper was published early online. Senior author Stephen W. Scherer is a HHMI international research scholar, a senior scientist in the Genetics and Genomic Biology Program at the Hospital for Sick Children in Toronto, Canada, and an associate professor of molecular and medical genetics at the University of Toronto.
