Why is my cat black when cats originated from small wild cats?
Some animals of any species are bound to have genetic mutilations which cause their coat, or part of it, to be a different colour to that which is normally used by the species, e.g albino animals. Your cat is black, because at some point during the domestication of cats, someone decided they would like a black cat. By finding the few wild cats with small amounts of black fur and breeding only these cats, each generation will have an increased amount of black fur, eventually ending up with your all-black cat. In the same way, poodles and pugs are descended from wolves, and were merely selectively bred to acheive the characteristics that they posess today.
