Modern speed traced to British mare from 300 years ago

Scientists in Ireland and Britain believe a genetic variation in the myostatin “speed gene” that promotes sprint ability entered the Thoroughbred breed via a single native British mare about 300 years ago, according to new research published Tuesday in the journal Nature Communications. And as precocity and sprinting ability became more prized, the gene’s presence has proliferated in the breed since the mid-1950’s, the research team has found.

A 16-person research team, led by Equinome genetic testing founder Dr. Emmeline Hill, analyzed molecular and pedigree data from 593 horses in 22 breeds in Europe, Asia, and North America; examined the bone and teeth samples from the skeletal remains of 12 famous Thoroughbred stallions foaled between 1764 and 1930, and also took speed-gene data from 330 high-performing modern Thoroughbreds on three continents, 40 donkeys, and two zebras.

The study found that the T-allele, which is linked to greater stamina, is ancestral in equids and that there was a single introduction of the C-allele, linked to sprint ability, not long before James Weatherby published Britain’s first General Stud Book – and effectively began closing the Thoroughbred registry to outbreeding – in 1791.

“The results show that the ‘speed gene’ entered the Thoroughbred from a single founder, which was most likely a British mare about 300 years ago when local British horse types were the preeminent racing horses, prior to the formal foundation of the Thoroughbred racehorse,” Hill said.

“Furthermore, we show that although the C-allele was rare among the celebrated racehorse of the 18th and 19th centuries, it has proliferated recently in the population via the stallion Nearctic (b. 1954), the sire of the most influential stallion of modern time, Northern Dancer (b. 1961),” according to the researchers’ abstract. As modern racing’s and buyers’ emphasis has moved more toward speed, sprint distances, and 2-year-old racing, breeders have continued to select for those characteristics and have kept the C-allele prominent in many jurisdictions.

“This just goes to show the power breeders have to shape the genetic makeup of their horses,” Hill said. “Decisions regarding the race pattern in each racing jurisdiction and the commercial demand for certain types will also rapidly influence the genetic make-up of the population.”

Hill, who also is a genomics professor at University College Dublin, was joined in the study by scientists from the University of Cambridge and Equinome, as well as collaborators from Trinity College Dublin, the Russian Academy of Sciences, and the Swedish University of Agricultural Sciences.