Bryan Caplan  

The Wonder That Is Dog

Where Numbers Come From... Who Wants More Kids?, Part II...

Richard Dawkins and I have something else in common: We're amazed by dogs:

If mutation, rather than selection, really limited evolutionary change, this should be true for artificial no less than natural selection. Domestic breeding relies upon exactly the same pool of mutational variation as natural selection. Now, if you sought an experimental test of Behe’s theory, what would you do? You’d take a wild species, say a wolf that hunts caribou by long pursuit, and apply selection experimentally to see if you could breed, say, a dogged little wolf that chivies rabbits underground: let’s call it a Jack Russell terrier. Or how about an adorable, fluffy pet wolf called, for the sake of argument, a Pekingese? Or a heavyset, thick-coated wolf, strong enough to carry a cask of brandy, that thrives in Alpine passes and might be named after one of them, the St. Bernard? Behe has to predict that you’d wait till hell freezes over, but the necessary mutations would not be forthcoming. Your wolves would stubbornly remain unchanged. Dogs are a mathematical impossibility.

Don’t evade the point by protesting that dog breeding is a form of intelligent design. It is (kind of), but Behe, having lost the argument over irreducible complexity, is now in his desperation making a completely different claim: that mutations are too rare to permit significant evolutionary change anyway. From Newfies to Yorkies, from Weimaraners to water spaniels, from Dalmatians to dachshunds, as I incredulously close this book I seem to hear mocking barks and deep, baying howls of derision from 500 breeds of dogs — every one descended from a timber wolf within a time frame so short as to seem, by geological standards, instantaneous.

Whenever someone tells me that humans are too genetically similar and/or haven't been around long enough for genes to explain human differences, I always bring up the dog. It's an uncomfortable parallel. Do you think Dawkins is willing to run with it?

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COMMENTS (5 to date)
Neel Krishnaswami writes:

Humans went through a severe population bottleneck in the recent evolutionary past -- it seems that modern humans are descended from between one and ten thousand people. We have a lot less genetic diversity than dogs. We do have more than cheetahs, which may all descend from a single pair -- they have so little genetic diversity that skin grafts from one cheetah to another are not rejected.

Loweeel writes:


He is. Look at "The Grasshopper's Tale" in the Ancestors Tale.

Dawkins doesn't deny the genetic difference inherent in race (IIRC, I think he may even analogize to dog breeds), but he does caution against finding a distinction from that difference.

Brad Hutchings writes:

But .. Behe ... appealed directly to a public that — as he and his publisher know — is not qualified to rumble him.

Behe exists because Dawkins exists. The above statement is why even people who would generally/thoroughly agree with him on the science find Dawkins so incredibly shrill and condescending as to be an embarrassment. When Trey Parker and Matt Stone pretty much agree with you and still savage you viciously in their animated TV show, you oughta take note. The same public that he complains about (what I call the 110 IQ crowd) are the same public that buys all his books, read his op-eds, and become insufferably bigoted against religious people. And I'm a happy atheist saying that.

You also have to love the evolution (or lack of it) of the evolution debate. On one side, we have various gradations and subtleties of non-scientists. On the other side, we have the same thing. Suggest to the evolution side that they discuss evolution as a theory, that is a best explanation of all the data we have and an explanation that has changed substantially in the past and will likely change a bunch in the future, and get accused of blasphemy. For them, science must be presented to the public as truth rather than the pursuit of truth. It's not only condescending, it's downright dangerous.

John Thacker writes:

Of course, not all traits emphasized via breeding are the results of mutations, or rather to say not mutations that occurred after breeding started. The breeds mentioned all are considered only a few hundred years old at most, and many remarkably diverged in that time. (Instantaneous time frame indeed.) The mutations built up over time before being emphasized in breeding, certainly, but as usual it's a little more complicated than Dawkins likes to pretend, though he does note that it's a two-step argument-- that the mutation rate of surviving mutations is high enough and that selection is fast enough to bring them out.

(Behe would presumably also point out that all the breeds of dogs still interbreed, of course, and emphasize the triviality of dog breed differences. I suspect that Dawkins would have issues comparing it to human genetic differences, as he wants to emphasize dog differences here but generally prefers, for understandable reasons, to minimize human genetic differences.)

Jacob T. Levy writes:

Well, humans have generations that last something like seven times as long as dog generations. Dogs have been domesticated for at least 15,000 years, maybe 20,000 or more. They evolved incest taboos that prevent the fast route toward selective-reinforcement-and-culling which really speeds change along. And dogs have many more offspring over a lifetime from which one can select reinforcing breeding pairs.

The geographic dispersion of humanity happened, say 10,000-40,000 years ago (depending on where). After 10,000 years ago, humans were subject to varying environmental conditions-- and did indeed evolve in different directions based on skin pigment and diet, and muscle mass and body size. (And no one denies this.) But the different environmental conditions didn't exert anything like the precise force of selection of humans selecting breeding pairs of dogs-- survival needs in one place just weren't that different from survival needs in another.

And it's only been 6000 years or so since the really great divide brought on by agriculture and permanent settlement-- the first event that meant that humans in different places might have needs for radically different traits in order to survive and reproduce. For a species that's not being deliberately interbred, has a small number of offspring, and reproduces starting at c. age 15 instead of c. age 2, 6000 years is trivial time.

In short: we haven't been around long enough for genes to explain very much-- sorry. We've been around for an order of magnitude less time than dogs in reproductive terms, and that understates the gap by a lot because of litter size, deliberate reinforcement, incest taboos, and so on.

And dogs seem to be unusually plastic anyway-- in no other domesticated species have we attained anything like the same range. (A cat is a lot closer to its primordial ancestor, and to another cat, than a Lhasa Apso is to a wolf or a St. Bernard.) Plasticity may itself be a trait, and one of the selection mechanisms at work-- plasticity has served dogs very well in evolutionary terms, and not all other animals have it.

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