Dogs Again
Great special on dogs on PBS this evening. (Nova; transcript to be available in a few weeks).
Lots of talk about how exactly dogs became domesticated, and they came to appear in so many different colours, sizes and shapes. The discussion confirmed some of my reading. It is probably not true that humans somehow domesticated wolves; rather, some wolves found it advantageous to be at least relatively tame, in order to get easy food.
A garbage dump is shown in order to visualize. All wolves would be attracted to the food. If a human appeared, the truly wild wolves would take off. A few tamer ones might stay, and discover their tame behaviour, since it is less threatening to the humans, causes them not to be treated like predators. Gradually, when the truly wild dogs try to come for a snack, they are chased off by the increasingly tame ones, who have made a home there.
There is evidence that tamer dogs have less adrenaline, and as soon as there was an advantage in being tame, dogs with less adrenaline would breed more of the same. (Lower adrenaline means less of a wild, snarly, fight-or-flight type of reaction). Remarkably, a lowering of adrenaline over generations has been shown to cause changes such as the raising of the tail, the lowering of the ears, and even the appearance of big, splotchy, black and tan type colours.
All domestic dogs are genetically the same. Yet some genes are switched on, and others are switched off, in each dog. A set of characteristics appears in a breed. The most long-standing breed types resulted from being used in a certain way, more than from careful breeding. Desert dwellers wanted dogs who could chase rabbits. They would reward/feed the fastest dogs in each generation, these would be the successful dogs who would breed, and the super-fast salukis would appear with certain colours, ears, tail, without any planning by humans. Herding, pointing, retrieving, all bring out only one or two steps in a wolf's hunting routine. It's only very recently that breeders would deliberately pick and choose a number of qualities, and deliberately breed for them. As one scientist said, this requires separation of animals in heat (these days, using a chain-link fence), and charts of family trees, etc.
Lots of great stuff, cute animation to make points, etc. Some cute, off-the-wall suggestions, such as that homo sapiens advanced over Neanderthals partly by using dogs, and indeed was first required to develop some language in order to communicate with dogs.
(Dogs may have lived closely with humans, sleeping close to them at night, for the last 10,000 years or so; yet they have been genetically distinct from wolves for 100,000 years. There must have been some pretty wild, testy dogs, only slightly domesticated, for a long time. 10,000 years ago, based on cave paintings and skeletons, there was probably very little differentiation of dogs by size or appearance; 5,000 years ago, the Egyptians show considerable differentation.)
Then the troubling part. The narrator (John Lithgow) states matter-of-factly that all the established breeds are inbred, and either have serious health problems already, or will have soon. One scientist says the whole breed standard business is madness for someone looking for a family dog, and there are too many unhealthy dogs being bred.
Then the silver lining to a cloud. When inbred dogs develop medical conditions that are rarer in dogs than in humans, such as narcolepsy, their being inbred makes it relatively easy to identify the gene that is affected. This will help with the treatment of human illness.
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