Some dogs are tall. As soon as a change and improve the living conditions of ancient man, especially with the transition to a sedentary, agricultural and cattle-breeding, to develop and improve the requirements for a dog. This prompted Rights to develop new specialized breeds. Performed artificial selection of dogs with useful qualities for him. Used other methods to improve the dogs. With the active human influence, purposeful breeding activity in different parts of the globe have been withdrawn and a proliferation of dog breeds suited for hunting, protection of homes and pets, transporting heavy loads, military purposes and so the transition to the Neolithic era to the development of agriculture and animal husbandry people actively involved in terms of their economic interests and the dog, which immediately reflected in its appearance and marked the beginning of rock formation. In contrast to natural populations, where the relative uniformity of support mechanism for stabilizing selection keeps out, removing the genetic and hence phenotypic deviations in the populations of dogs included a new mechanism, called DK Belyaev, destabilizing selection, removes restrictions on the form-building process. It is understandable that people in the selection of a dog's offspring guided by its practical usefulness, and under his tutelage maintained that in the wild eliminated.
Cause the same type-forming process is the accumulated load of mutations, inherited from the wild ancestor and early-stage mutation. In the wild species accumulated mutations could only be recessive and exist in a heterozygous state. Naturally, the dominant mutations, for example, hairless, in nature were condemned to death.