Though dogs are so close genetically to wolves that many taxonomists consider them to be a subspecies, most people wouldn't let a wolf lick their hand as readily as a Shih Tzu. When animals are domesticated, as the dog was, their traits change; an artificial selection occurs over many generations, which, in the case of the dog, probably happened through unconscious selection bias among ancient humans and their canid hangers-on.
Other animals, too, saw similar phenotype changes through the process of domestication. When wild boars were first domesticated in areas of both modern Turkey and China, the farmers who bred them preferred animals with less fur, more meat and a tamer disposition. Similarly, a famous 2020 study on wild foxes in urban areas found that the city-dwelling creatures had distinctly different physical traits, such as "a noticeably shortened wider snout with a reduced maxillary [jaw] region" and with "a braincase appeared to be smaller in the urban habitat" — which suggested they were becoming semi-domesticated.
