Ah, the cat lady. Frequent subject of jokes, guest on Oprah, and cruel update of the old maid scenario. We know you well. But what we didn't know was that the strange predilection for cats among older females may actually be caused by a parasite. Toxoplasma Gondii, which infects some 60 million Americans, is dependent on the digestive systems of cats to complete its lifecycle. New research has suggested that the parasite, when in a non-feline body, may induce behaviour changes to increase their unwitting host that will greatly increase their chances of being eaten by cats. So, in rats, this manifests as a fondness for cat urine. In humans, it may involve living alone and owning many cats. When the infected owner finally shuffles off her mortal coil, then the starving cats will, naturally, take matters into their own hands. Paws. Mouths. Whatever. The Toxoplamsa is ingested, and the mighty circle of life continues.
All of this is highly speculative, but once again proves what I've long believed: science can explain anything, and truth really is stranger than fiction.