Canine transmissible venereal tumor, or CTVT, is an unusual contagious cancer that affects dogs around the world. Live cancer cells are transmitted from dog to dog during mating. Dr. Elizabeth Murchison, a cancer geneticist at Cambridge University, has sequenced the genome of this cancer. The results suggest that it has survived continuously for 11,000 years. The genome also reveals a lot about the cancer's original host, which turns out to be an ancient dog with a dark coat and pointy ears that was similar to an Alaskan malamute.