You would expect that how fast a racehorse could run would eventually plateau as the physiological limits of the animal are reached. Despite the fact that thoroughbred horses have been selected on their race times and performance, it was noted in the '70s that this was in fact the case, and this apparent lack of reaction to selection came to be known as the “Cunningham Paradox.”
But a new study has shown that this might not actually be correct. By analyzing the race times of every “elite” race occurring between 1850 and 2012, a Ph.D. student from Exeter University has shown that far from leveling off, racehorses have in fact been getting faster. Whether this is down to successful genetic selection, or other improvements such as training or jockey tactics, is still unknown.
“There has been a general consensus over the last 30 years that horse speeds appeared to be stagnating. Our study shows that this is not the case and, by using a much larger dataset than previously analysed [sic], we have revealed that horses have been getting faster,” explained Patrick Sharman, who led the study published in the Royal Society journal Biology Letters. “Interestingly, both the historical and current rate of improvement is greatest over sprint distances. The challenge now is to find out whether this pattern of improvement has a genetic basis.”
So why in the past has it been thought the opposite? One possibility is that by selectively breeding horses for one trait, it has a detrimental effect on others. For example, by breeding North American thoroughbreds for an increase in musculature and leg length – in the hope that it will increase their stride and thus their speed – breeders might actually have inadvertently selected for an increase in fast-twitch muscle, which reduces a horse’s overall stamina.
Horse racing garners big bucks. In the U.K. alone, it’s estimated to contribute around $5.44 billion (£3.45 bn) to the economy. Thus, there is a lot of investment riding on the industry to breed the best and the fastest horses. It’s thought that Frankel, the highest rating racehorse ever, could be worth an eye-watering $157.76 million (£100m) in stud mating rights. But in light of the Cunningham Paradox, hasn’t spending all this money been in vain?
Well, apparently they might now be vindicated. After looking at over 600,000 race times run by over 70,000 horses, the researchers have shown that there have been significant increases in speed. Whilst there was not much difference between 1850 and 1997, the years between 1997 and 2012 saw an increase in speed by about one second. Now that might not sound like much, but in the world of horse racing, it’s massive. It would mean that a horse from today would outrun a horse from 1990 by about seven body lengths.
What the study cannot tell us, however, is the cause of this dramatic difference. It might be down to improved training regimes, or other environmental factors such as riding technique. But equally, the researchers note that during this period there was also an increase in the commercialization of horse breeding, so the effect could genuinely be down due to improving their genetics. The scientists plan to look deeper into the data to try and figure this out.