The common ancestor of humans and the rhesus macaque monkey lived about 25 million years ago. But despite that vast gulf of time, our chromosomes still retain plenty of evidence of our shared heritage. Rearranging the X Chromosome, Or NotA team of scientists at the National Cancer Institute recently documented this evidence by constructing a map of the rhesus macaque's DNA, noting the location of 802 genetic markers in its genome. Then they compared the macaque map to a corresponding map of the human genome. The order of thousands of genes was the same."About half of the chromosomes are pretty much intact," said William Murphy, a member of the team, now at Texas A&M University.