Image: Flickr/Tsutomu TakasuYou might think that after centuries of breeding, racehorses have reached their peak speeds. And previous studies supported that. But not this one! According to this study, which used "a much larger dataset covering the full range of race distances and accounting for variation in factors such as ground softness," racehorses have gotten faster over the past 150 years or so, an improvement evident even in the past 15 years. Holy Secretariat!Racehorses are getting faster. "Previous studies have concluded that thoroughbred racehorse speed is improving very slowly, if at all, despite heritable variation for performance and putatively intensive selective breeding. This has led to the suggestion that racehorses have reached a selection limit. However, previous studies have been limited, focusing only on the winning times of a few elite races run over middle and long distances, and failing to account for potentially confounding factors. Using a much larger dataset covering the full range of race distances and accounting for variation in factors such as ground softness, we show that improvement is, in fact, ongoing for the population as a whole, but driven largely by increasing speed in sprint races. In contrast, speed over middle and long distances, at least at the elite level, appears to be reaching an asymptote. Whether this reflects a selection limit to speed over middle and long distances or a shift in breeding practices to target sprint performances remains to be determined." Related content: NCBI ROFL: The hidden menace of non-equine horses. NCBI ROFL: How baseball outfielders determine where to run to catch fly balls.Hawkmoths jam bat radar with ultrasonic blasts from their genitals.