There have been a few badly optimized horse breeding trends. There was a fad in the 1980s for decorative Arabian horses with thin legs. They were not even rideable, but were used as a tax shelter. That, fortunately, is over. The much tougher lines of endurance Arabians now dominate again. They're still beautiful, but good ones can do the Tevis Cup, 100 miles through the Sierras. (Several friends of mine have ridden that.)
Dog breeding is much worse. There are many dog breeds that are barely functional.
Genetic diversity is a very interesting topic that’s well worth exploring, but it seems to me that Occam’s razor requires us to consider the possibility they just had a really good, well timed dosage of performance enhancing drugs for Secretariat back in the day.
> After he died, Secretariat’s heart was reportedly measured at almost 10 kilograms – twice as much as normal. This appears to have been a physiological fluke, however, as it isn’t a trait reliably passed down to offspring.
In humans, enlargement of internal organs (including heart) is know to be a side effect of using growth hormone as a PED. Wiki says [0] that "Extracted growth hormone was used since the late 1950s", so in 1973 it was already a well known technology.
> Occam’s razor requires us to consider the possibility they just had a really good, well timed dosage of performance enhancing drugs for Secretariat back in the day.
No, Occam's Razor suggests the simplest possible explanation. To suggest that they figured out how to dope horses in 1973 and then promptly forgot how for the next fifty years is a complicated explanation. The simplest explanation, the Occam's Razor explanation, would just be that it was a fluke of nature.
I think it's surprising that the article predicts the impacts of gene editing to be relatively small.
> Even so, the prospects for exceeding current records through gene editing are slim. Today’s racehorses are already tightly optimized for speed, balancing strength against the cost of carrying additional muscle mass. Adding more muscle is relatively low-hanging fruit, and if this were the key to unlocking greater speed, selective breeding would likely already have brought it about.
It's a whole new tool in the toolbox, and can introduce mutations that didn't first arise by chance in order to be then spread with selective breeding.
I agree with this specific claim from the article... though maybe not for the reasons it puts forward.
The reason being that breeding is akin to black-box optimization -- it doesn't concern itself with genomic details at all, the phenotype being the optimization target. If we want to do gene editing directly on the other hand, we need to have some way of mapping a genotype-level edit to a phenotype-level effect.
The first CRISPR racehorses edited MSTN, which is the single best-understood speed locus because centuries of breeding already sorted it. Thus: we had a population that was varying at the MSTN gene site -> regressing by performance on the sequenced genomes of those horses flagged this site -> CRISPR was able to make a targeted edit there. Ideally we need naturally occurring, phenotyped variation to find sites worth editing.
Notice how this confines gene editing to spaces where we have confirmation that a genetic site affects the wanted phenotype. Entering a new trait-space is hard. So to your point that gene editing can introduce mutations that didn't first arise by chance: I think it's true, but novel mutations are precisely where we don't have any data (and any one experiment takes years and is very expensive).
Gene editing today is successful in specific research areas: polled cattle, PRRS-resistant pigs, disease knockouts, etc... These are places where the mechanisms that the gene-editing is supposed to target are well understood (theoretical machinery is more built out here).
Cloned horses are becoming really common in polo — the best polo player in the world won the Argentine Open back in 2016 with six clones of his favorite horse [0][1]!
There have been a few badly optimized horse breeding trends. There was a fad in the 1980s for decorative Arabian horses with thin legs. They were not even rideable, but were used as a tax shelter. That, fortunately, is over. The much tougher lines of endurance Arabians now dominate again. They're still beautiful, but good ones can do the Tevis Cup, 100 miles through the Sierras. (Several friends of mine have ridden that.)
Dog breeding is much worse. There are many dog breeds that are barely functional.
Genetic diversity is a very interesting topic that’s well worth exploring, but it seems to me that Occam’s razor requires us to consider the possibility they just had a really good, well timed dosage of performance enhancing drugs for Secretariat back in the day.
> After he died, Secretariat’s heart was reportedly measured at almost 10 kilograms – twice as much as normal. This appears to have been a physiological fluke, however, as it isn’t a trait reliably passed down to offspring.
In humans, enlargement of internal organs (including heart) is know to be a side effect of using growth hormone as a PED. Wiki says [0] that "Extracted growth hormone was used since the late 1950s", so in 1973 it was already a well known technology.
[0] https://en.wikipedia.org/wiki/Growth_hormone_therapy#Extract...
> Occam’s razor requires us to consider the possibility they just had a really good, well timed dosage of performance enhancing drugs for Secretariat back in the day.
No, Occam's Razor suggests the simplest possible explanation. To suggest that they figured out how to dope horses in 1973 and then promptly forgot how for the next fifty years is a complicated explanation. The simplest explanation, the Occam's Razor explanation, would just be that it was a fluke of nature.
I think it's surprising that the article predicts the impacts of gene editing to be relatively small.
> Even so, the prospects for exceeding current records through gene editing are slim. Today’s racehorses are already tightly optimized for speed, balancing strength against the cost of carrying additional muscle mass. Adding more muscle is relatively low-hanging fruit, and if this were the key to unlocking greater speed, selective breeding would likely already have brought it about.
It's a whole new tool in the toolbox, and can introduce mutations that didn't first arise by chance in order to be then spread with selective breeding.
I agree with this specific claim from the article... though maybe not for the reasons it puts forward.
The reason being that breeding is akin to black-box optimization -- it doesn't concern itself with genomic details at all, the phenotype being the optimization target. If we want to do gene editing directly on the other hand, we need to have some way of mapping a genotype-level edit to a phenotype-level effect.
The first CRISPR racehorses edited MSTN, which is the single best-understood speed locus because centuries of breeding already sorted it. Thus: we had a population that was varying at the MSTN gene site -> regressing by performance on the sequenced genomes of those horses flagged this site -> CRISPR was able to make a targeted edit there. Ideally we need naturally occurring, phenotyped variation to find sites worth editing.
Notice how this confines gene editing to spaces where we have confirmation that a genetic site affects the wanted phenotype. Entering a new trait-space is hard. So to your point that gene editing can introduce mutations that didn't first arise by chance: I think it's true, but novel mutations are precisely where we don't have any data (and any one experiment takes years and is very expensive).
Gene editing today is successful in specific research areas: polled cattle, PRRS-resistant pigs, disease knockouts, etc... These are places where the mechanisms that the gene-editing is supposed to target are well understood (theoretical machinery is more built out here).
I don't know why the article goes on so much about Secretariat. Flat races are horse races on easy mode. Steeplechases are proper horse racing
Someone should really get around to cloning secretariat.
Cloned horses are becoming really common in polo — the best polo player in the world won the Argentine Open back in 2016 with six clones of his favorite horse [0][1]!
[0] https://knowablemagazine.org/content/article/technology/2026...
[1] https://www.wired.com/story/cloning-came-to-polo-things-got-...
> today, only the genus Equus survives, which includes horses, zebras, asses, and donkeys.
What about hippogriffs?
Asking for a friend...
Good article. Doesn't seem to cover when they turned into anthropomorphized girls however.