To add my 2 cents - It seems, that breeding practices show that dog has niether more nor less "genetic elasticity" than other domesticated animals - e.q., cows and horses In 1700, the average British cow weighed about 170 kilograms; by 1800 their average weight reached 360 kg. Impressing? As to the horses - Google for "Tennessee Walking Horse"... Dogs are simply easier to "pick and choose" - average 6 puppies per bitch twice a year, one human life is enough to establish a "breed"... keeping it together is another question. That's why the biggest puzzle is how those aboriginal breeds manage to survive through milleniums, and still remain recognizable? Perhaps the answer will be the high level of genetic divercity inside the breed itself, which form very differnt breed types in aboriginal populations... CAO, CO, etc...