In reading this dog breeding thread, and some of the links, breeders and dog fanciers appear to speak with near absolute authority about the ability to determine not only proper physical conformation, but temperament through proper breeding.
IIRC in reading SDMB threads over the years on topics related to human genetics or the history of eugenics, a common theme is you really can’t select out specific traits like homosexuality or intelligence and breed for or against them because (recessive dominant mumble mumble).
Why are dog breeders so convinced they can accomplish something that human geneticists tell us is impossible?
A dog goes from newborn to sexually mature in a year or so. So you can produce one generation per year, and you can also create a dozen pups a year. So in 3 years, 1 becomes 12 becomes 144 becomes 1728 (plus 2nd litters for the 1 + 12 and a 3rd litter for the original 1) . That gives you a lot of ability to sharpen whatever you’re looking for.
When well-fed (with plenty of BGH) humans become sexually mature at about age 12 & produce a litter of ~1 per year. BIG difference.
Humans have a lot more free will. Even if you did breed them aggressively for certain behavioral traits, you’d still get more outliers. For non-behavioral traits they’d probably be about as malleable as dogs.
I think most pundits don’t assert that you can’t breed people, but rather that you shouldn’t. If we had five thousand years to work the project and were willing to cull the vast majority of the offspring of each generation, I have no doubt we could achieve the equivalent of Pekinese or Great Danes.
Dog breeds are the result of very intensive selective breeding (often including very close inbreeding, including parent/offspring and between siblings) over many generations. Individuals that don’t conform to the desired type are culled (or were at least formerly) or at the very least eliminated from the breeding stock from that line. Nothing remotely similar has ever been done with humans; ethical considerations and a generation time about ten times longer make it essentially impossible. Maybe a 1000-year Reich could get somewhere, but that’s what it would take.
Even so, dog breeds often don’t breed true to “type.” As remarked above, there is continued pretty strong selection on the breeding stock. If that selection were relaxed, and all individuals were allowed to breed, you would begin to see even less uniformity.
>I think most pundits don’t assert that you can’t breed people, but rather that you shouldn’t.
I think this is the important point. Many of us would not like to have been given our characteristics to suit somebody else - a parent who likes blonde hair, say, or a government that likes brave soldiers. There are fish breeders who help fish evolve into having enormous bulging eyes that point up. I don’t know why the breeders do that, and find it disturbing, but since the creatures are only little fish it’s easy enough just not to think about. If people were breeding humans in ways I found similarly disturbing and inexplicable, not thinking about it would be impossible and trying to prevent it would be inevitable.
I think, though, that technically it would work to some degree. It’s amazing how many characteristics tend to be similar between twins raised apart, for example. I think it is obvious that intentional breeding could manipulate all these characteristics.
In fact some people say they have tried in their own personal lives. In G. Gordon Liddy’s autopiography, “Will”, he describes choosing his wife in part for her genetic breeding potential. On the other hand, a friend of mine with very bad allergies says he’s chosen not to have children because he doesn’t want to pass them on. These are both breeding programs on a small and subjective scale.
But of course the role of environment is important too. We manipulate this all the time to favor certain traits in people of the next generation. We send them to school and to music lessons. We teach them manners. We seek constructive play opportunities for them. We are deliberately messing with the nurture side of the nature vs nurture dichotomy of influences - as well we should. There’s nothing creepy about doing so, in the typical well intentioned ways that parents have been doing it for thousands of years.
This is the old upper class (British) sterotype: “Have your flings with the pretty young things, son, but when you want to settle down you’ll need a handsome [horse-faced] woman with child-bearing hips”. I suppose that’s been true at least sometimes.
What does bovine growth hormone have to do with anything? Age of menarche has been dropping since at least WWII, long before bovine growth hormone became a concern. Which it isn’t, when it comes to menarche and fertility in humans.
Unless you’re talking about big game hunters, and that seems unlikely.
This is one of my most well worn soapboxes. What we consider “good breeding” in dogs is called, when translated to humans, racism and eugenics, and is considered a very bad thing.
There’s a branch of evolutionary psychology (a branch I consider racialist, FWIW) which holds that Ashkenazi Jews have been breeding for high IQ in much the same way that greyhounds have been bred for speed.
I’ve always thought of Kevin McDonald a Nazi sympathizing loon, but he’s also a tenured professor in psychology,
What about people who know or strongly suspect that they carry recessive genes for (say) sickle-cell anemia or hemophilia? I’m sure at least some of them keep an eye out whether a potential spouse might carry the same recessive gene. Can anyone confirm whether this is the case?
It’s often a bad thing in dogs, too. Many of the purebred lines carry “standard” defects (hip displasia’s, bone defects, early-onset senility, eye problems, etc., depending on the breed) that are becoming more and more common, and some breeds usually can’t even give birth without human assistance. In other words, we’ve unnaturally selected them for traits which in our absence would cause their extinction.
Nevertheless, the pace of dog breeding is an astouding example of just how powerful a force selection is in evolution – eight or ten thousand years ago (a mere blink of an eye for evolutionary change), these breeds were all basically wolves. Now they’re so varied that if an alien biologist showed up, he/she/squee would almost certainly assign the breeds to different species based on their morphological characteristics.
Thing is, dogs aren’t humans. Putting a human in a small crate that s/he can’t get out of without your help and going off to work would be considered a very bad thing, even if you came home often enough to give them potty breaks. But it’s an acceptable thing to do to a dog.
If you’re going to say selective breeding is bad, you have to decide where to draw the line. Is it OK to selectively breed people? Animals? Plants? Bacteria?
We’ve done the same thing for many of our food plants. Wild peas are assisted in reproduction by having their pods explode, domesticated peas aren’t. Domesticated peas might have trouble reproducing without humans- is that bad?
Various Jewish groups offer screening for the recessive gene for Tay-Sachs disease (there’s a blood test for it). What a person might do if they find that they and their SO are carriers varies. Some might break off the relationship, some might do prenatal screening if they were expecting a child and would abort if the fetus were going to develop Tay-Sachs disease (most rabbis that don’t say decisions like this should be left to the couple would say that Tay-Sachs disease is an acceptable reason for abortion).
Some carriers for hemophilia might use various methods to try to make sure their children are girls rather than boys, since hemophilia is sex-linked. These days, they might use artificial insemination- sex selection for avoiding disease is generally considered more acceptable than sex selection for other reasons.
I think the difference is that many of the dog’s traits are undesirable even to us – they’re an unwanted side effect of rapid genetic engineering, universally recognized as a defect in the animal. We’re living with them because the obvious solution (breed them outside the “breed” to bring back genetic diversity) is currently out of fashion–antithical to the idea of a “pure” breed. Yes, I’d say that’s bad; for both the dogs themselves and for fans of the breeds. Especially if several breeds will cease to be viable over the next few decades because of the accumulation of these defects, as has been suggested.
Fascinating thread-in Rober Heinlein’s classic SCI-FI story (“METHUSALEH’s CHILDREN”), a rich man left a bequest, which paid long-lived people to associtae and marry. This started around 1860-by the 1990’a, the children of these unions were living well past 100 years.
Is such a thing possible? And, WHY do dometic dogs have such short life spans?
You seem to be implying that dog breeders can select out the specific trait of homosexuality. Despite the domestic dog being one of the many animals that display homosexual behavior, no dog breeder has ever done so. So there’s no reason to think that something that has never been done for dogs could be applied to humans – no mumbling required, there.
Also a bit of a leap to conflate what we call “intelligence” in dogs with intelligence in humans.
What do you mean short life spans? Compared to humans or to wild dogs? I doubt wild dogs live as much as the domestic dogs (from around 10 for large breed dogs to 15 or up in smaller breeds).
How were they determining that a person was long-lived? Long-lived usually means outliving your ability to reproduce. Were they just encouraging breeding between people with long-lived relatives?
As to the dog life span, I don’t think it’s been determined why any animal has any particular life span.
>the children of these unions were living well past 100 years. Is such a thing possible?
Sort of. Humans apparently are pretty healthy and robust until the age at which their children are becoming pretty independent because propagating their genes forward works better when they are. But we’re not so healthy and robust at older ages than this because propagating genes forward doesn’t work much better. Last I heard, in addition to the genetic diseases we are more familiar with, the very fact of growing old and dying is nothing more than the cumulative effect of a big number of undocumented genetic illnesses that have crept into our genetic makeup because there is little to drive them out. In other words, people don’t die of old age per se, they accumulate so many unnamed genetic illnesses that they can’t survive them all.
Although, I think getting long-lived people to produce young doesn’t really work, because people have to be doing well in their 80’s, bare minimum, to be relatively long lived, and they’re not reproducing by that time. If you want to engineer a superrace of long living people, you have to find people whose parents or grandparents lived a long time, or you’d have to bring lots of people into your program and then start dropping them from the program when their parents die young. In other words, you need to create a new artificial means of making long live an advantage in breeding.
Dogs live about as long as wolves do in captivity. Which should be no surprise.
For mammals, lifespan is roughly correlated with size-- larger animals tend to live longer. Not a hard and fast rule, but generally true. Also, there is a correlation with heart rate-- a fast heart rate means a shorter lifespan. Of course, size and heart rate are also correlated, so those aren’t really two independent variables.
As best I can recall, the Methuselah’s Children plan was to encourage people to marry whose grandparents/great grandparents were known to have lived to old age.