Cat owners have many reasons why keeping a cat or two is a pleasurable experience. And usually somewhere near the top of the list is the fact that cats use a litter box and take the time to cover up their business. We generally chalk this up to fastidiousness, but the reasons are more complex than that.
In cats, like many other land mammals, urine and feces have been adopted as a marking behavior that transmits social and reproductive signals to other members of the same species. Cats are territorial by nature and their society is structured in a dominance-controlled hierarchy governed by strict rules of conduct. They mark their territory by depositing pheromones, chemicals that convey information about an individual to other cats. They use a variety of methods to mark their territory in this manner, including scratching, rubbing against things… and leaving their feces uncovered.
In colonies of feral cats, subordinate individuals cover up their feces, while dominant stray cats leave waste uncovered in conspicuous spots. Most indoor cats bury their waste, probably because they feel subordinate to their human family. However, in multicat households, the dominant cat will sometimes leave feces uncovered to announce his presence and status. Uncovered feces means the territory is taken.
In the wild, cats cover their feces to prevent attracting attention of predators. Burying feces reduces odors and this might be an important factor for the survival of the weaker individual that does not want to advertise his or her presence to others.
Covering their "business" is an instinct that kittens are born with, and begin this ritual just as soon as they are able. They do not learn it from watching their mothers, as mother cats never eliminate near the nest. Kittens just start burying their waste of their own accord and will even do it when they are orphaned. Just show a young kitten a litter box and, chances are, he will eliminate in it without any fuss and then will be nice enough to cover up the mess.
Cats make great companions. They are warm and fuzzy, loveable, interesting, and fun. And the fact that they maintain such convenient bathroom habits helps us like them even more.