Dogs and DNA

I saw two fascinating programs about dogs on Nature this week. If you have a chance to see them, I highly recommend them.

Dogs were domesticated in a very short time. The transition from wolf to dog happened possibly within one human lifetime about 15,000 years ago. And when I say 'from wolf to dog', I'm actually talking about physical changes to the animals' skeleton and teeth, as well as behavioral changes. This seems impossible according to classic Darwinian theory, although there is a lot of recent evidence that species can evolve very fast to adapt to changing enviornments.

For example, in the 1950's some Russians were trying to breed foxes for their fur. The problem was they were too wild to breed in captivity and had to be kept in separate cages. So a geneticist was brought in to try to create foxes that would breed in captivity. He decided to breed just the least aggressive foxes. He chose the foxes by putting a heavily gloved hand into the cage. The ones that just sniffed at it curiously were chosen to breed, the ones that responded aggressively were not.

In just 10 years, there was a completely different breed of animal. Their facial structure changed so they didn't have huge crushing jaws, their teeth shortened, even the coloration of their coats changed and they began to act like affectionate dogs. In fact, their skeletal changes were the same as those found in what's called the 'proto-dog', and kind of post-wolf, pre-dog breed as we know them, found in archaeological sites. The program showed films of the changed foxes, and of them wild and aggressive, then different looking and playing happily with children a few years later -- just a few dog generations later.

So now, there is a theory that what happened to domesticate dogs is this: About 15,000 years ago people began to live in permanent settlemens, the problem of garbage was created. When they moved around in a nomadic lifestyle, they just left the garbage behind and it disappeared before they returned, but once they were settled in one place, they had to have some kind of rubbish dump where they took bits of waste, the skeletons of animals they were done with etc.

These dumps would have attracted animals, including wolves. The wolves that stayed closest to the dumps had a better chance of survival, because they were simply closest to the food. It's called 'flight distance' - how far a creature flees when he feels endangered. Short flight distance = increased survival (in this case). Imagine the humans bringing out the remaining bits of carcasses and dumping them, and the wolves that stayed very near by were the most likely to get the food.

They didn't say this in the program, but I'm speculating that this would have been the marginal wolves, the young males who were without a pack, the lowest on the totem pole. The most desperate ones. The hungriest ones. Maybe even the loneliest ones, as they definitely like company. The strongest, the alphas, would have had other, better, resources for food and could afford to retreat farther.

Anyway, as demonstrated in the Russian experiments, when you select for curiosity and lack of aggression (which is pretty much the same thing as flight distance), you also select other genes inadvertently and thus, you can change very quickly the actual species itself.

Isn't that amazing?

The DNA part is that a Swedish geneticist is looking at the matrilineal DNA of dogs. He started out doing forensic work with dog hairs and that led to a huge international experiment of over 3000 dogs from all over the world. Basically, it looks like they all came from East Asia somewhere, maybe China. But that's still in progress.

And based on Bryan Sykes studies of patrilineal DNA in people, the story is incomplete without looking at that, too. So there will be more to come on that.

One more note is that dogs may actually have had a great impact on human civilization. There was some speculation about whether it would have been possible to domesticate other animals without dogs (dogs were the first domesticated animal). It showed border collies in a very hilly part of Cumbria herding sheep (2,000 sheep in 2,000 mostly vertical acres) in ways and in places that humans simply couldn't do. One of the scientists interviewed pointed out that herding is exactly like hunting, except that the dogs stop before killing. Since this is the kind of terrain that is the natural terrain of sheep and goats, man couldn't have herded them without dogs ever. He actually said that without dogs, it's possible we'd still be hunter gatherers. Though I think that overstated the case.

Whatever the case is, it's pretty remarkable to see working herding dogs at work -- the kinds of signals that they have to understand are very complex. things like -- hey you left one behind, and no, get that other group over there.

Also, the served an important protective function just as watch and guard dogs in early times, making villages more secure and secluded farms more secure. Changing the kinds of settlements people were safe in.

Finally they interviewes an interesting Inuit man, who said that without the dog his people would not have survived in the Arctic circle. They depend on them to find seal holes, protect them from Polar Bears (yes, they can get rid of bears), get them home in whiteout conditions when humans can't tell where they are. And to keep humans from falling through the ice. Dogs will stop short because they can sense in their feet the changes below the snow.

I watched the second show after I wrote this, and it was also fascinating. I'll just note one thing. Dogs are the most varied species in the world -- 500 different breeds recognized. And in the mid-19th century, there were only 40. The proliferation since then of pet dogs -- lap dogs -- has caused the variety.

So much I'm not saying from these fascinating programs, but this is already too long.