Stop horsing around

‘Stop horsing around’…that was definitely it; that was what we were going to call this instalment of Science Lite. But we were beaten to it. By a horseshoe crab. 

This rather nifty (…if, we openly admit, a little ‘hacky’) headline has already been used here - in an article about a rather useful aspect of said sea-creatures blood. So, not for the first time we have been pipped at the post by a marine arthropod (...don't ask). But from one beast to another – the horse. Specifically a rather surprising gap in our knowledge regarding the humble bovine: We don’t know how fast they can run; that is to say how fast they could run.

Now, given the sheer amount of money tied up in horseracing – the British Horse Industry Confederation suggest the ‘economic impact’ of horseracing is at least £3.7bn, with a staggering £10bn at least bet on races every year – we had assumed that speed would be the one thing we definitely did know about our equine friends.

And, up until recently we thought we did. Studies had suggested that thoroughbred race horses really aren’t getting any faster – despite the best efforts of tweeded horsey types foisting the progeny of their ‘prize’ studs on the world of horseracing.

Indeed one study reported no increase in the speed of winning racehorses in the US since the early-1970s. So was that it? Had we bred the horse to go as fast as it could go? It certainly looked as if we reached the performance limit of their evolution.

Naturally this began to raise the hackles of the moneyed horse owners as they questioned paying large amounts of money to stud farms aiming to breed future winners.

Understandable perhaps. Who among us can honestly say their money at the stud farm was well spent…? So, OK, you may be forgiven for thinking this isn’t the kind of problem that would ordinarily engage the scientifically curious – the gambling curious perhaps…

But actually it is scientifically interesting. Very much so. The thoroughbred business is a focussed hot bed of selective breeding, which is of course a kind of evolutionary shortcut – a shunt to a new physiological destination – the insights of which should hint at some of the wider mysteries of inheritance. As such there has been interest in a new study, published in Royal Society Biology Letters, which suggests that elite race winning speeds have, in fact, improved greatly since 1850.

Specifically, Patrick Sharman, a PhD student at Exeter University, seems to have found that racehorses can sprint faster. Over a short distance a modern day horse, he says, would beat a horse from the early 1990s by seven horse lengths.

Now, they are keen to point out that their study is not proof that selective breeding is responsible for this – for that they’d need to subtly pick apart the genetics of inheritance more closely. But certainly the hints are there that by selective breeding – by the very channelling of evolution as if it were water being directed along a canal – man has made the horse faster.

That is at once amazing and, somehow, slightly worrying. Of course it has happened in animal domestication of many sorts; but to have such power over the genome – and indeed phenome – of another species…

Some may argue that it has always been thus. That species rarely exist in isolation – the relationship between them after all is at the very nub of what natural selection is. And that selective breeding is just an extension of this. But to see mankind ‘produce’ such an efficient running machine from an organism which would certainly not have taken this evolutionary course via natural selection, well, it certainly gave us pause for thought.

In our introduction we mentioned the horseshoe crab – an animal which hasn’t altered significantly for 450 million years – a living fossil no less. What a different story for the racehorse. Our rather strange impulse to make them run faster has created an entirely new branch on the great tree of life.