Amy Harmon explains some dog genetics in the NY Times today, in an article focused on whippets. The problem is that undesirable characteristics of some breeds are homozygote recessives for alleles that the breeders have been strongly selecting:
FORT MOTT STATE PARK, N.J. — When mutant, muscle-bound puppies started showing up in litters of champion racing whippets, the breeders of the normally sleek dogs invited scientists to take DNA samples at race meets here and across the country. They hoped to find a genetic cause for the condition and a way to purge it from the breed.
It worked. "Bully whippets," as the heavyset dogs are known, turn out to have a genetic mutation that enhances muscle development. And breeders may not want to eliminate the "bully" gene after all. The scientists found that the same mutation that pumps up some whippets makes others among the fastest dogs on the track.
They're going to apply genetic screening to eliminate the "bully" whippets, although the article doesn't explain just how. I suppose, they will use DNA screening results to decide to breed only heterozygotes with homozygote dominants, yielding a 50-50 chance of fast-running heterozygote offspring. But it seems to me, the breeders are just as likely to mate a bully with a slow homozygote dominant, getting 100 percent heterozygotes as a result.
It's like hybrid corn, except with dogs!
In fact, if they could make purebred lines for three or four alleles at a time, they would really vastly improve their ability to breed for fast dogs by hybridizing.
It's interesting how people find it much more disturbing to have a categorical difference between to individuals (like an allele) instead of a continuous difference. I mean, speed is a continuous variable, and we all know that different people vary in how fast they can run. This has been an unremarkable fact since the beginning of time. But somehow when genes get involved, people get all funny about it:
"It would be extremely interesting to do tests on the track finalists at the Olympics," said Elaine Ostrander, the scientist at the National Institutes of Health who discovered that the fastest whippets had a single defective copy of the myostatin gene, while "bullies" had two.
"But we wouldn't know what to do with the information," Ms. Ostrander said. "Are we going to segregate the athletes who have the mutation to run separately?" For the moment, it is whippet owners who find themselves on the edge of that particular bioethical frontier.
It was not exactly news to breeders that speed is an inherited trait: whippets were developed in the late 1800s specifically for racing. But knowing that one of her dogs was sired by a carrier of the gene, said Jen Jensen, a whippet owner in Fair Oaks, Calif., makes its championships seem "less earned." Ms. Jensen's suggestion that a DNA test be required for all dogs and that the fastest ones without the mutation be judged and raced separately, however, has not gone over well.
I suppose the disquieting part is that genetics somehow reduces everything to simple mathematics. Keeping two strains of loser dogs for crossbreeding really fast ones will take away from the stuff about "spirit" and "magic":
Even those who want to exert more direct control over dog DNA, however, agree that no genetic test can predict the intangible qualities that make a dog great.
If a dog does not have the spirit to run a race, it is not going to win, said Betsy Browder, a whippet owner in College Station, Tex.
"'Keenness' is what we call it," she said. "Just like you can have a human athlete who's really lazy, and all the genes in the world aren't going to help."
Yeah, until they find the gene for that, too.
This stuff about separating out the human athletes by genotype is nonsense. There will always be this problem -- is it an athlete's training or gene X? Or as-yet-unknown-effect gene Y? Or gene Z in combination with her genetic background? Is it fair? I suppose that depends on the other consequences of genes X, Y and Z, and the entire genetic background. Which is the same question as, "Is life fair?"
At the moment, training discrepancies are quite a bit greater than most (though not all) genetic differences between athletes. But that won't remain true forever -- eventually, all credible competitors will have the same training -- or at least training that they believe to be the same. The training may even be specialized for their genotype. All they're doing is substituting one kind of variance (environmental) for another (genetic).
The only thing fairer is flipping a coin at the start of each race. Maybe some of them will want to trade, but I doubt it.