The domestic cat has been a part of human civilization for at least 4000 years, and possibly as long as 9500 years. Their top-notch hunting skills and adaptability to human cohabitation made African wild cats invaluable to ancient societies for the purpose of controlling vermin. These small, fierce, and agile hunters were willing to devour agricultural pests including mice, birds, and insects. They can adapt to and thrive in a variety of climates, including deserts, chilly northern lands, cities, and even on board sailing vessels.
Cats are a fairly efficient companion animal, requiring less food than dogs, being readily litter-trained, and having a great deal of social independence. While I am not going to say that they are better or worse than dogs, I will say that they are different, and they do not require as high a level of social conditioning and interaction as a dog. A pet cat, if treated kindly and well-habituated to human contact, will become well-socialized without a great deal of training and effort on the human's part.
The cat body makes them a particularly pleasurable companion animal. They are large enough to not be terribly fragile, while they are still small enough to be relatively easy to handle, carry, and have on one's lap. They have an attractive appearance, with large, inquisitive, forward-facing eyes, a beautiful form with interesting curves and shapes, large, endearing pointed ears, and, usually, a lovely tail. Most have a soft, thick fur coat that is pleasurable to stroke and nuzzle; those that do not have fur have very warm, soft, suede-like skin that also feels good to our human fingers.
Cats typically are pleasant-smelling in and of themselves; their litter habits can generally be trained so that they are not too intrusive to our noses. They make pleasant sounds, rewarding kind treatment with a rumbling purr that soothes humans, even though we do not make that sound ourselves. They sometimes make other vocalizations, which vary from one cat to another, but it is quite rare for them to be as loud and unpleasant-sounding as a barking dog. Some of them walk around our homes, singing to themselves with bright miaowing; my Dom does this, apparently just to hear the sound of his own voice, and I enjoy his musical talents during these sessions.
Cat behavior is the very best part of their companionship. Even a homely feline can bring joy to his humans with his sensitive, loving presence. They seem capable of sensing our feelings, and come to us in our times of sadness to comfort us. They can be loyal, and they often attach themselves to a single person as their One and Only. They are playful, amusing us with their ability to switch from gentle friend to instinctive wild hunter with the flick of a favorite toy. They show us the very best of sensuality, dignity, and patience, serving as role-models for those of us who sometimes set those qualities aside.
Cats are brightly intelligent, highly emotional, and amazingly communicative. With tail, ear, and whisker movements, they are able to express themselves more clearly than most of us manage to with words. They roll their eyes at us, sigh in resignation, frown when confused, and smile when contented. A lashing tail will tell you when they're through playing, and an ear turned to the side is a cat's equivalent to a raised eyebrow--you can practically hear them thinking, "Oh, REALLY now." Their sheer range of emotion rivals our own, and their ability to express it perhaps even surpasses ours.
Most amazing of all is how we can generally turn these little creatures loose in our homes, trusting them to wander about as they please, and, in most cases, not giving a second thought to leaving them to their own devices while we are away. There is an incredible bond of trust, and it is simply inexplicable how both our species and theirs are able to comfortably cohabitate as if it is the most natural thing in the world. Cats and humans somehow learn to interpret one another's languages so naturally and artlessly that it is easy to imagine that we are somehow designed to fit together as two parts in a symbiotic whole. While other creatures have become domesticated, cats are unique in the way they are harmoniously accepted into families as essential members.
Their adaptation to life with our species--and our dependence on them, not just as workers, but as companions--is a testament to their success in evolution. We are quite lucky that they decided we were worth bothering with in the first place. A life without them is hardly worth living!