This happened before neutering and spaying became prevalent. While the turnspit breed might no longer have been curated, the dogs themselves likely mingled with other breeds and have various mutty descendents today (or perhaps they have become part of certain pure breeds!).
What's interesting to see here is how ephemeral the results of centuries of selective breeding can really be. A very specific and specialized form of dog disappeared almost overnight once the artificial selection maintaining it was removed. It's a testament to the ability of genes to repair themselves given the least bit of diversity to work with. The incredible variation in dog breeds is really due to relatively small amounts of mutation, and here we see how rapidly those mutations can be repaired. It's humbling to realize that humans have altered the genes of dogs far less than their forms indicate.
> What's interesting to see here is how ephemeral the results of centuries of selective breeding can really be. A very specific and specialized form of dog disappeared almost overnight once the artificial selection maintaining it was removed. It's a testament to the ability of genes to repair themselves given the least bit of diversity to work with.
That's a pretty weird way to look at it. 'Repair'? No one is shining x-rays at turnspit dogs. What happened is that the selection pressures changed, and as quickly as they adapted to the turnspit niche, they adapted to the alternative niches like being mutts or lapdogs. Selection is fast, artificial or 'natural'.
Which incidentally suggests that we're wasting a lot of potential. (Like dogs which can sniff cancer; why aren't we trying to breed dogs to do that better?)
One of the cornerstones of selective breeding is systematic inbreeding. This brings out recessive traits and encourages the accumulation of what we would normally consider mutations and errors. By selecting individuals that have desired traits, this engine of change is harnessed to produce the desired end results.
Consider how we would view humans who had been selectively bred long enough to change their form as drastically as some dog breeds have been changed! We would be horrified by them. However, the deformities accumulated by this population, when reunited with a larger population, would soon disappear. No doubt we would would view this as repairing the damage done to their genomes.
As for breeding dogs with the ability to sniff cancer... First, you have to get your hands on the raw materials. i.e. Find dogs who already can smell the stuff. Then you have to hope at least some of their offspring will have that trait. Next, you need to figure out how to reliably train dogs with the ability to smell cancer to actually do so and communicate the results, and you're probably going to have to do this with dogs you don't necessarily know actually have the ability. Also, you will need to be around people with cancer on a routine basis so you can test/teach your dogs. I'd be willing to bet few oncologists will say things to their patients like, "Gee, you're absolutely riddled with cancer! How would you like to help out with our cancer-sniffing-dog breeding program before you snuff it?". Finally, you have decades or even centuries of work ahead of you before you'll have a breed on your hands with greater ability than random gifted individuals in the greater dog population.
The fact that some dogs can smell at least some forms of cancer suggests that there is a mechanism for detecting cancer to be discovered. It would be much faster and far more useful to determine how dogs detect cancer and develop instruments directly based on that method. The state of modern science is such that breeding animals just takes too long.
> One of the cornerstones of selective breeding is systematic inbreeding. This brings out recessive traits and encourages the accumulation of what we would normally consider mutations and errors.
It may bring out recessive traits, but why would it increase the mutational load? Those are no more useful in a turnspit dog than in a sheepherding dog. If your dog is growing 3 eyes because of a particularly nasty de novo error, that's going to be selected against both by the breeder and by other pressures.
> Consider how we would view humans who had been selectively bred long enough to change their form as drastically as some dog breeds have been changed! We would be horrified by them. However, the deformities accumulated by this population, when reunited with a larger population, would soon disappear.
There's plenty of physiological variation among humans; are we really horrified by Pygmies?
> First, you have to get your hands on the raw materials. i.e. Find dogs who already can smell the stuff.
Not that hard, since they've already been reported, implying that they're not so rare as to not exist.
> Next, you need to figure out how to reliably train dogs with the ability to smell cancer to actually do so and communicate the results, and you're probably going to have to do this with dogs you don't necessarily know actually have the ability.
Solved by animal trainers eons ago: rewards for correct selection. How do you think drug dogs are trained?
> I'd be willing to bet few oncologists will say things to their patients like, "Gee, you're absolutely riddled with cancer! How would you like to help out with our cancer-sniffing-dog breeding program before you snuff it?".
Culture cancer in dishes or something. Somehow, getting cancer samples doesn't seem to be a huge existential problem for cancer researchers.
> Finally, you have decades or even centuries of work ahead of you before you'll have a breed on your hands with greater ability than random gifted individuals in the greater dog population.
Decades is completely ordinary a timeline in medical research, so not a problem. And I suspect it'll be on the former rather than latter timescale: you only want one thing, and selection can act very fast. Consider how long the Russian fox experiment took, for a much more trivial goal.
> It would be much faster and far more useful to determine how dogs detect cancer and develop instruments directly based on that method.
Oh, and how well has that worked so far...? Perfect, meet better... Really, you're making this all out to be much harder than it'd actually be.
What's interesting to see here is how ephemeral the results of centuries of selective breeding can really be. A very specific and specialized form of dog disappeared almost overnight once the artificial selection maintaining it was removed. It's a testament to the ability of genes to repair themselves given the least bit of diversity to work with. The incredible variation in dog breeds is really due to relatively small amounts of mutation, and here we see how rapidly those mutations can be repaired. It's humbling to realize that humans have altered the genes of dogs far less than their forms indicate.