The evolution of the domestic cat or housecat is unique within the natural histories of the various animals that humans have domesticated over the past ten thousand years. Evolutionary biologists today generally agree that the evolution of cats actually involved a sort of bargain struck between humans and cats: humans tolerated wild cats around their food supplies because they had remarkable skills killing vermin (rats and mice), and cats gradually adapted to an environment in which they were surrounded by humans.
This process stands in contrast to the usual process of domestication of wild animals, which involved humans deliberately assuming a dominant position in a relationship with social pack animals, like dogs, or herd animals, like cattle. Pet owners today will probably identify with these different origins: while dogs tend to be highly devoted to their masters, cats tend to be much more independent, more or less going where they like and doing as they like.
The house cat is a member of the family Felidae, a group of small feline predators which are generically referred to as cats. The most remarkable members of the family are far larger than domestic cats: lions, panthers, cheetahs, jaguars, leopards, and tigers. Even these are smaller than some relatively recent but extinct relatives, such as the sabre-toothed tiger. The earliest known member of the family, based on the fossil record, lived about ten million years ago. Since then, cats have adapted into a wide variety of species as they successfully spread into many different environments.
In most cases, domestication represents a very important point of divergence in the evolutionary history of an animal species, as it begins to respond to purely artificial selection pressures (i.e. deliberate breeding for certain traits) rather than natural selection in an unmanipulated environment. This is only partially the case with house cats, however. Today’s house cat often tends to be a solitary animal. Even if its ancestors were not, today anthropologists and biologists generally agree that it was not domesticated the same way that most species are: finding a pack or herd animal and then substituting a human for the alpha male, effectively taking charge of an existing social group. This strategy proved effective in domesticating livestock for food (see sheep and cattle, for instance), as well as hunting companions (dogs). It also meant that breeding became a deliberate process manipulated by humans. Long before they actually understood the genetic mechanisms underlying reproduction and change, humans were deliberately breeding species to draw out preferred traits and suppress others.
In contrast, house cats did not undergo such a deliberate process of artificial selection. The two species simply grew to tolerate one another: humans accepted cats for their remarkable ability to control the rodent population, and cats accepted humans because their food storage tended to attract large numbers of tasty vermin. The main change over time for the house cat, therefore, was simply that it shrunk, from the African wildcat into today’s much smaller cats. More recently, deliberate breeding of cats has been used to create a considerable variety of different appearances in cats. However, even this pales in comparison to the much broader range of traits present in different dog breeds. And cats still, for the most part, simply refuse to obey commands the way dogs do.