What is it about cats that makes them such good house pets?
Dear Straight Dope:
As I write this, my pet cat is purring beside my desk, and after extending an arm to scratch him under the chin (increasing the purring), I'm inclined to ask: Why cats are so cuddly? (It's not smartness--I know dumb when I see it, and it's right besides me now). Why cats rather than another animal such as rabbits, apes, aardvarks, 'coons, 'possums, badgers or skunks? (OK, I can see why not skunks. But they can be cuddly and cute, too.) What in the cat predisposed it to be the engaging furry companion we know? I understand the ancient Egyptians were the first to mass-tame them for pest-control purposes, but still, why not the abovementioned animals (or their ancient Egypt equivalents)?
I don't think you're going to ever get a precise answer to a question like that, but you hint at the most likely factor: the Egyptians weren't necessarily out to produce something cuddly, they were out to produce something useful. Though animals have been domesticated for at least 12,000 years, breeding for pleasure or cosmetic purposes--i.e., the "house pet" mentality--is a relatively recent development.. A society has to reach a pretty high level of organization before significant numbers of people can afford to waste food on animals that contribute nothing practical. The Egyptians were not such a society--at any rate they don't seem to have been into house pets as such. Since there was no practical use for a tame aardvark or hare, they saw no point in trying to domesticate them. For most of the time they've been associated with people, cats and dogs--even breeds like poodles and dachshunds--have had practical uses that were perceived as a fair tradeoff for the cost of keeping them around.
The second factor, also crucial, is whether an animal can be domesticated. Some animals can't be--which is not to say they can't be tamed. (You can tame a zebra or falcon, but they've never been successfully domesticated.) If you know enough about an animal's life history, behavior, and, most importantly, how it interacts with its kind in groups, you can predict with some certainty whether it will respond well to attempts at domestication. If the topic interests you, there are many discussions of it in the literature. Jared Diamond provides an excellent historical analysis in his Pulitzer-winning Guns, Germs, and Steel, in which he discusses how the non-random global distribution of large, domesticable animals was a key factor in determining how cultures and civilizations developed.
The final aspect, cuddliness, is partly a result of breeding. A mutant pet that is more cuddly and endearing than its predecessors is more likely to be used by its owner to breed more pets like it, if it's the sort of pet for which cuddliness is a relevant consideration. Pigs, for example, aren't particularly cuddly, despite centuries of breeding, because they haven't been bred as housepets. Dogs and cats, on the other hand, have been intensely bred, resulting in things like tiny little lap dogs (or fluffy cats) with big eyes and flat faces. Animals of this sort are perceived as cuddly due to their resemblance to human infants--they trigger our parental instincts. Few animals are capable of having that psychological effect, so it's no surprise that few have worked their way into our homes as completely (and parasitically, given how little practical purpose most of them serve) as cats and dogs.