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Thanks for your thoughtful question. I think this idea comes from a misunderstanding of what a pariah/ village dog is. There is this idea that all dogs come from our pet population dogs and that all dogs are mixes of breeds. In reality a vast majority of the world’s dogs are free-living animals that were never any breed. Those dogs as you mention have a certain look to them, (we have a nice blog article on this entitled “What is a dog breed”). This look is due to natural selection as well as some random events, for example if the founder of a new population has spots or floppy ears and they are not deleterious those will occur at a high rate. If a pure bred dog strays into the village dog population, it’s traits tend to be less well adapted to this environment and will be selected against and quickly swamped out by those of the better adapted local village dogs. There is actually a village in Venezuela that the Coppinger’s write about in their recent book “What is a dog” where they let St. Bernard’s breed with their village dogs, to try to make them look more like the famous war dog Nevado. Of course, the St. Bernard is much too large to be well adapted to surviving as a village dog in this area and while a few of their village dogs have some St. Bernard traits for a time, they do not survive as well and do not produce as many pups as the regular village dogs, so without continued reintroduction of St. Bernards their village dogs look like the normal village dogs from anywhere else in that climate.