An Economist Walks into a Brothel by Allison Schrager

An Economist Walks into a Brothel by Allison Schrager

Author:Allison Schrager
Language: eng
Format: epub
Publisher: Penguin Publishing Group
Published: 2019-04-01T16:00:00+00:00


Horse breeders have a short-term economic incentive to inbreed their horses. Decades ago, a desirable stallion bred with sixty or seventy mares a year, but now the hottest ones will breed with nearly two hundred. So Thoroughbreds have become increasingly inbred, even though this inbreeding is inefficient: breeders spend a small fortune on stud fees and face long odds of producing a horse that can race, let alone win.

Thoroughbred horses are inbred by definition: 95 percent of modern Thoroughbreds are thought to trace their ancestry to a single horse, the Darley Arabian, born in 1700. Dr. Mathew Binns, an equine geneticist and a partner at Equine Analysis Systems, a consulting service that assesses horses for investment and breeding using science, estimates that inbreeding has increased among Thoroughbred horses in the last forty years. The increase started to become noticeable in the 1990s, a few years after 1986 tax reform increased incentives to breed commercially (selling a horse before it races), a practice that eventually became the industry norm.* Despite the increase in inbreeding,* Binns says it’s important to have some perspective: “The average Thoroughbred is still less inbred than a pure-bred dog.”

Possibly the most prolific modern racehorse was Northern Dancer, who was a Kentucky Derby and Preakness winner. Northern Dancer’s stud career lasted more than twenty years and spanned multiple continents, producing many progeny who also had exceptional racing careers. At its peak in 1984, his stud fee was $500,000, more than $1.2 million in 2018 dollars, six years before his death in 1990.

But he lives on. Today, almost every single Thoroughbred is related to Northern Dancer, often on both their mother’s and father’s sides, multiple times. According to David Dink, a Kentucky-based writer who has spent his career studying Thoroughbred bloodlines, Northern Dancer was present in the bloodlines of 96.5 percent of the 38,821 foals sold between 2012 and 2015. Dink says Northern Dancer was present two to three times in the lineage of 64 percent of the horses. He was present four times or more in 20 percent of the foals.

The economics of breeding has created incentives to sire more Hapsburgs* (albeit beautiful ones) for two reasons. First, a yearling’s father largely determines its value, and there is a fairly small pool of desirable stallions that will bring in big money at yearling auctions. There are only so many champions new to stud and even fewer racehorses with successful offspring.

Second, inbreeding increases the odds of getting a sprinter, a horse that also sells well. Sprinters are homozygotes: if you breed two sprinters, you get a sprinter. Northern Dancer’s gene type is unknown, but Emmeline Hill suspects he was a heterozygote (with sprinter and distance genes, as he won longer races). She says there’s a “high likelihood” he had at least one sprinting gene, which, when mixed with a hybrid mare, will produce a sprinter 25 percent of the time. If the mare is a sprinter (she has two sprint genes), there’s a 50 percent chance the foal will be a sprinter too.


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