For the first 8,000 years of their relationship with humans, cats pretty much took care of their own breeding. People kept them for one purpose - hunting rodent - and they are already perfectly designed for that. More than 100 years ago, however, we began systematically breeding cats to appeal to our aesthetic tastes. Hair length, color, coat pattern, as well as head and leg proportions contribute to the "look" of specific breeds.
Look at enough cat bodies and faces, and you'll see two distinctl.