<html><body style="font-family: 'Helvetica Neue',Helvetica,Arial,sans-serif; font-size: 12px;"><h1 class="css-1bo5zl0 e164j1a30">A new study asks whether racehorses have hit their genetic peak</h1><h2 class="css-13b9ga2 e1fr8l080">But the breeders trying to improve them may be missing a trick</h2><div class="css-kpd7oo e1mrg8dy0"><br /></div><div class="css-1r2sn2n e1mrg8dy0"><div class="css-1a032gy e1mmklaa0"><div class="css-6y4s51 e15inkaq0"><div class="css-1t4jlmt e1w2n8zt0"><div class="css-w0h03k egtgihk0"><div> Jun 7th 2023</div><div><div class="css-1902i5q egtgihk0"></div></div></div></div></div></div></div><div class="css-qswdso e1sipfu40"></div><div class="article-gifting css-1c8dfkn eplrptc0"><div class="css-vu6x35 e5tfikp0"></div></div><p class="article__body-text article__body-text--dropcap"><span>F</span><small>or decades</small>
there was an apparent paradox in horse-racing. The sport is lucrative
(Mage, the winner of this year’s Kentucky Derby, earned his owner $1.9m)
and simple—the fastest horse wins. Horses with good results and a good
pedigree are used as breeding stock for the next generation.
Horse-breeders were armed with plenty of data, a single trait to
optimise, and strong incentives to do so. Yet several studies suggested
that, despite their efforts, race times were not improving.</p><div class="css-1lm38nn e1lug06p0"><div>Listen to this story.<span class="css-1fs0t47 emsvzne0">Enjoy more audio and podcasts on <a href="https://economist-app.onelink.me/d2eC/bed1b25">iOS</a> or <a href="https://economist-app.onelink.me/d2eC/7f3c199">Android</a>.</span></div><div class="css-1h1me4y e1lug06p1"><div class="css-vu6x35 e5tfikp0"></div></div></div><p class="article__body-text">The
most common explanation was that, physiologically speaking, it was
increasingly difficult to breed a horse that ran faster than existing
horses already do. The modern thoroughbred racing horse dates back at
least three centuries. Perhaps the years of selective breeding had
already discovered and exploited almost all of the breed’s genetic
potential. </p><p class="article__body-text">That did not make sense to
Patrick Sharman, a racing enthusiast and geneticist at the University of
Exeter, in England. After all, cattle breeding has been going on for
hundreds of years, yet continues to create cows that produce more milk.
Artificial selection applied to chickens is still raising plumper birds.
It would be odd, he thought, if racehorses were the one domesticated
animal that humans could no longer improve. So, along with Alastair
Wilson, who had once been his <small>P</small>h<small>D</small> supervisor, he started digging.</p><div class="adComponent_advert__V79Pp adComponent_incontent__Bxd2J advert--inline"><div><div class="adComponent_adcontainer__dO1Zm"></div></div></div><p class="article__body-text">Their
first paper was published in 2015, and examined a dataset of British
races going back to the 1800s, much larger than in other papers. It
found that, contrary to accepted wisdom, horses have indeed been getting
faster. In sprint races—those run over five to seven furlongs
(1-1.4km)—the average speed needed to win has increased by about 0.1%
each year since 1997. Their latest paper, published on May 27th in <i>Heredity</i>,
tries to assess how much of that improvement is attributable to
genetics. In other words, is the time-, energy-, and money-intensive
profession of horse breeding worth the faff? </p><p class="article__body-text">The
answer appears to be yes—though less so than breeders might like. By
linking a large performance database, containing nearly 700,000 race
times recorded in Britain between 1995 and 2014, to a family tree of
more than 76,000 horses, they found that speed is heritable, albeit
weakly, and that breeding is improving it, but slowly. </p><p class="article__body-text">The
boost is most pronounced for sprints and middle-distance races (8–12
furlongs). Drs Sharman and Wilson conclude that around 12% of the
variation in the speed of horses at these distances comes down to
genetics. (This is about the same heritability as neuroticism or
lifespan is in humans.) And they found that improvements to those
genetics accounted for more than half of the increase in speed seen over
that time period. The rest, says Dr Sharman, is probably down to hard
to measure, non-genetic factors such as better nutrition and veterinary
care or improved jockeying technique.</p><p class="article__body-text">When
it comes to longer-distance races, it is not clear that times are
improving. One reason, says Dr Sharman, may be that the genes that are
good for sprinting do not necessarily make for good endurance athletes.
Breeders seem to be selecting for sprint performance because it offers
quicker commercial returns. Sprinters tend to start running at around
two years old, long-distance horses at three.</p><div class="adComponent_advert__V79Pp adComponent_incontent__Bxd2J advert--inline"><div><div class="adComponent_adcontainer__dO1Zm"></div></div></div><p class="article__body-text">Horse-breeders
may face other trade-offs, too. Selecting solely for speed may increase
the risk of injury. (Churchill Downs racecourse, where the Kentucky
Derby is run, suspended racing for a month from June 7th, after more
than a dozen horses had died following injuries over the past six
weeks.) Temperament matters, too—a fast horse is of little use if it is
unrideable. </p><p class="article__body-text">Despite the difficulties,
there is also evidence that breeders might be leaving some horsepower in
the genetic tank. At least in Britain, says Dr Sharman, breeders still
rely, to some degree, on their professional judgment when assessing
horses. Less intuitive, more objective statistical techniques have
transformed other sports, most famously baseball, over the past couple
of decades. Horse-racing too may be ripe for its “Moneyball” moment.<span>■</span></p><p> </p><br /></body></html>