The other evening, as I watched our cat throw up on the living room carpet for the fifth time in a week, glare at me smugly and then saunter off to shed hair on the new sofa, I thought to myself: Who invented pets? What motivated that first primitive man who took the time to capture an animal and, rather than eating it immediately, took it inside the cave, tied a bow around its neck on Christmas Day and called it "Fido"?

To me, this is an unexplainable phenomenon. According to a 2005 study by the National Pet Owners Association, the following menagerie is wandering about aimlessly and destroying the insides of American’s homes as we speak: 73 million dogs, 90 million cats, 11 million reptiles, and 28 million assorted "small animals," by which I think they probably mean 2-year-old boys.

I’m as guilty of this madness as the rest. I’ve had numerous creatures in my homes over the years, although not all of them technically qualified as "pets" under my strict three-prong test, the first part of which is that the thing must be able to eat from a bowl rather than live in it. This rules out tropical fish, which I had in an aquarium at one of my college apartments. Ultimately, we had to throw the whole mess in the woods when the algae developed to such a degree that it started climbing out of the water and stealing our beer at night.

The second requirement to officially qualify as a pet is that the creature must have a legitimate life expectancy of more than, say, a week. This allows me to scratch my little sister’s gerbil off the list. During his second day in captivity, "Harry" managed to escape from his plastic cage, scurry across the kitchen counter, down the wall and squeeze himself through a tiny crack beneath the floorboard. This caused my sister, who was about 7 at the time, to lie on the floor and scream until my father was called home from the office to kick a gaping hole in the dining room wall, retrieve the shivering vermin with an oven mitt and drop it back into the cage, whereupon it instantly puffed up to the size of bean-bag chair and died.

Third, and most important, a pet can only be a dog or cat. Let’s face it - snakes, pot-bellied pigs and talking birds are not pets. They’re simply beasts living among the deranged. Accordingly, my first pet was Boris, a beagle that my parents acquired a year before I was born. Boris was a fairly typical dog until he made the mistake of sleeping in the driveway of our neighbor Mr. Bunch, who backed his car out of the garage one morning and ran over Boris’ head. This resulted in Boris losing his left eye, after which he walked only in circles for the remaining seven years of his life, which if you think about it is not such a bad thing because pets rarely have any important errands to run. Boris eventually died in 1979 at age 16, which, when computed into the human years of a person whose head was crushed by a Chrysler, comes to something like 643.

After Boris, we owned a series of cats, the most notable of whom was Winston, a big yellow brute who lived with my parents from 1981 until 1998. At about age 10, Winston began doubling his weight every six months until he was roughly the size of a pastry chef. Concerned, my mother took Winston to the veterinarian, who performed ultrasound, magnetic resonance and very expensive tests in which he looked at samples of Winston’s saliva under the microscope and then exclaimed, "I think you’ve been feeding him too much!" My parents, perhaps wisely, retired from the pet business after Winston was laid to rest in a piano case.

That brings us to Pandora, the cat who’s lived with me and Amy the last 17 years. Or should I say we’ve lived with her. She’s a full story to herself, but that will have to wait for another day. Right now, I have to go tell Amy to clean the carpet again.