A comparison of the mouse genome to the human genome by researchers at Celera Genomics suggests that the genome of mice is nearly identical to that of human beings.
Comparing mouse chromosome 16 with human DNA, the researchers found that 97.5 percent of the mouse genes were also present in human beings. This contradicts longstanding estimates that the mouse genome may vary from humans by as much as 15 percent.
The major lesson here is that genes are important, obviously, but it is how those genes are expressed and regulated that appears to be what is most important in differentiating between relatively closely related species (mice and human beings are believed to share a common ancestor as little as 100 million years ago).
Arguments that rely on the apparent similarity of genomes between two different species (such as, say, chimpanzees and human beings) are far less compelling than they appear.
Source:
Just 2.5% of DNA turns mice into men. NewScientist.Com, May 30, 2002.