To the famous names from horseracing, synonymous with thrilling victories—Seabiscuit, Northern Dancer, Secratariat—add this one: C-allele 66493737. That’s the scientific designation for the specific gene researchers find in thoroughbreds that tend to be very fast. And the speed gene, researchers have discovered, has been spread mainly by the efforts of two of Canada’s greatest horses—Nearctic and the aforementioned Northern Dancer. A study published in the journal Nature Communications, based on the work of 16 scientists from Britain, Ireland, Sweden and Russia, tracked the gene by analyzing hundreds of horses, living and dead. Remains of a dozen great champions from 1764 to 1930 were among them. That key gene was traced to a single British mare from about 300 years ago, but its main modern sources were Northern Dancer, the Ontario-born winner of, in the U.S., the 1964 Kentucky Derby and Preakness Stakes, and, in Canada, the Queen’s Plate. Nearctic, owned by the late Toronto business mogul and horse breeder E.P. Taylor, was Canada’s top racehorse in 1958. Both Dancer and Nearctic retired from the track to legendary careers in stud, siring many champions.