In our past and our present, humans have enjoyed the company of both cats and dogs as household companions, in roughly equivalent numbers: according to one recent survey, there are now more cats than dogs in our houses, but more of our houses have dogs (since cat owners are more likely to have more than one cat). Yet, in examining science fiction visions of tomorrow, we encounter a strange dichotomy. Cats are virtually ubiquitous: they are central figures in Robert A. Heinlein stories like "Ordeal in Space" (1948) and The Door into Summer (1957); travel in spaceships in Arthur C. Clarke's "The Haunted Spacesuit" (1958), Gordon R. Dickson's Mission to Universe (1965), the film Alien (1979), and the series Star Trek: The Next Generation (1987-1994); are intelligent aliens in the Star Trek episode "Assignment Earth" (1968) and the film The Cat from Outer Space (1978); and employ enhanced powers to function as heroes in Cordwainer Smith's "The Game of Rat and Dragon" (1956) and Andre Norton's The Zero Stone (1968). There are also numerous stories about humanoid cats or catlike aliens, including the infamous film Cat Women of the Moon (1953), Smith's "The Ballad of Lost C'Mell" (1962), and Fritz Leiber's The Wanderer (1964). And it is not only in literature and film that one frequently finds cats: as anyone who has walked through the art show at a science fiction convention can testify, science-fictional or fantastic cats are a regular theme in the paintings, sketches, and sculptures on display. Indeed, cats are so common in the genre that there was actually a panel at the 2008 Los Angeles Science Fiction Convention on the topic of "Are There Too Many Cats in Science Fiction?"

Dogs, in contrast, appear to be relatively rare in the science fiction futures of all media, with few examples coming to mind. As one piece of evidence, I found that a Google search for the exact phrase "cats in science fiction" yielded 368 hits, while a similar search for "dogs in science fiction" yielded only seven. Could the reason be simply that most members of the science fiction community, like myself, tend to like cats better than dogs? Or is there some logical reason for this curious imbalance in the genre's predictions?

One must begin by acknowledging that there is one type of science fiction future in which dogs remain prominent: prophecies of either a forced or voluntary return to a pre-technological existence. After all, before the development of modern civilization, dogs were unquestionably valuable companions: in a world of constant danger, it was useful for vulnerable humans to have animal companions with superior hearing who could alert their masters to the approach of predators or enemies and, when people were attacked, a loyal dog could be an effective ally in fighting off assailants. Thus, in pessimistic science fiction stories depicting futures in which our advanced civilization has been destroyed or abandoned—like George R. Stewart's Earth Abides (1949), Harlan Ellison's "A Boy and His Dog" (1969), or the film I Am Legend (2006)—it is not surprising to find that dogs remain important friends to humanity; in one such story, Clifford D. Simak's City (1952), intelligent dogs have even replaced humans as the rulers of a pastoral future world where cats are curiously absent. Similarly, one would naturally expect to find dogs on Earthlike planets or space habitats where human settlers are leading a rustic lifestyle; for example, an adorable dog named Nixie plays a central role in Heinlein's "Tenderfoot in Space" (1958), as he accompanies his young master and his family when they emigrate to Earth's newest frontier, the jungles of Venus.

However, a majority of science fiction stories envision futures distinguished by ongoing scientific advances, on Earth and on other worlds, and in such environments, as is already the case today, dogs might be regarded as nothing more than obsolete technology: we now have burglar alarms to detect intruders, and we now have mace and pepper spray to ward off assailants. Nobody in a futuristic society is going to need a dog around the house as much as their ancestors did.

Of course, one can argue with equal force that cats represent obsolete technology as well, since today, we also have other ways to rid our households of rodents and other small pests, the traditional function of cats. Yet, cats can readily justify their continuing presence in our homes, not only because they, like dogs, can still be lovable friends, but also because they have proven to be remarkably adaptable to our modern, cramped, urban styles of living. Cats are happy to stay indoors all of the time, to spend most of their time sleeping in some comfortable location, and to use litter boxes when they have to relieve themselves. For such reasons, it made perfect sense for Data of Star Trek: The Next Generation to have a pet cat on board the Enterprise—such an animal would be no trouble at all on a starship.

In contrast, dogs regularly wish to go outdoors and, if kept indoors too long, they can become rambunctious and destructive, running around rooms, knocking over furniture, chewing on shoes, and so on. For dog-owners on Earth, now and in the future, this problem can be solved by the daily chore of walking the dog. Yet, dogs accompanying humans who venture into space would instantly die if they went outside of their spaceships or their outposts on airless planets. Moreover, even if one could keep a dog happy in a spaceship or on the Moon by giving it a special spacesuit to wear for outdoor excursions, there remains the indelicate reason why dogs always have to go outdoors, a sort of business that cannot be taken care of while wearing a spacesuit in a vacuum. True, systems for eliminating waste could be built into doggy spacesuits, as they are now built into human spacesuits, but what about those times when dogs are indoors and their needs are urgent? It seems that dog-owners in space would be obliged either to force their dogs to wear spacesuits all of the time, or to routinely deal with unpleasant messes on board.

Thus, when you are cataloging all of the innumerable mistakes that doomed the television series Star Trek: Enterprise (2001-2005), do not forget to include the bizarre decision to have Captain Archer bring a dog along on board his starship Enterprise. Indeed, if it seems that the crew of this series never quite bonded the ways that other Star Trek crews bonded, if these characters never seem quite as comfortable carrying out their duties as the characters from the other series, consider the fact that these crew members are living and working in a starship that must have been permeated with the faint-but-constant odor of dog poop.

All right, you say, we can certainly posit that scientists of the future will come up with some convenient, unobtrusive method to solve this particular problem, but the excretory habits of dogs represent only one aspect of a broader issue. Whatever other characteristics we wish to observe in our future worlds, there is an almost-universal desire for a future that will be clean—indeed, almost antiseptically clean. As I have noted elsewhere, the buildings of today that most resemble the buildings of science fiction futures are hospitals, where everything is always spic-and-span; in the towering skyscrapers and starships of tomorrow, we never observe spider webs, smudges, or piles of clutter. This is another reason why cats can so easily fit into the future, for they are obsessed with being clean, and indeed, may devote hours every day to meticulously licking and grooming themselves.

However, whatever else one might say in defense of dogs, it must be conceded that they are not by nature clean. In addition to the random manner in which they dispose of their waste products, dogs are never disinclined to get dirty, and never do anything to keep themselves clean. One of the ordeals of dog ownership is the need to regularly give the dog a bath, a task that, given the dog's persistent refusal to cooperate, may not get any easier with advanced technology. Thus, in visions of an immaculate future ranging from Things to Come (1936) to Gattaca (1997), it is almost impossible to imagine dogs running freely down their corridors; they would be fiercely incongruous in such pristine settings. However, a cat lying on a shelf somewhere and observing passers-by would not seem out of place.

Writers and filmmakers have other motives for excluding dogs from their future worlds. In years to come, we like to imagine, humans will be more mature, more sedate, more like our parents, and conspicuous displays of emotion will be frowned upon. And cats represent the epitome of cool, always determined to observe strange events with no sign of a reaction save for widened eyes. When their masters come home after a long absence, cats typically will first ignore them, then casually stride over near them and present themselves for a little petting. Given their constant air of calm and worldly wisdom, it is hardly surprising that the ancient Egyptians chose to worship cats, for they truly comport themselves like superior beings.

While cats are always under control, however, dogs are always out of control, reacting in a wildly-physical manner to any provocations; when their owners come home, they run madly toward them, panting with joy, and may even knock them over with the exuberance of their welcome. While cats always act like adults, in other words, dogs always act like children, and no sane person could ever contemplate worshiping a dog. Such creatures that perpetually display immature behavior, then, would inevitably seem inappropriate in the setting of an advanced future world. Consider another example, the briefly-glimpsed future world of Bill and Ted's Excellent Adventure (1989), wherein our descendants sit calmly on thrones, listening to the world-transforming music of the Wyld Stallyns; one can readily envision a cat sleeping in one of their laps, but a dog that runs up and yaps at the heels of Bill and Ted would utterly spoil the mood.

In sum, I would argue, when writers are crafting their future worlds, they find it easy to include cats, since these animals would appear to epitomize the predicted future of the human race—indoors, clean, and sedate. Conversely, since they see dogs as epitomizing humanity's outdoor, dirty, and rambunctious past, they think of them only when developing futures that resemble early, pre-industrial societies. To answer the question that those panelists at Loscon wrestled with: no, there are not too many cats in science fiction, because it is reasonable to assume that cats will become our principal companions in the future, accompanying humans as they construct and inhabit the soaring metropolises of the future, and as they travel in spaceships to explore and colonize other worlds.

Interestingly, there are clear signs that scientists on the frontiers of technology share this attitude and are working hard to better prepare cats for their future role as humanity's best friends. To address the main reason why people today do not have cats—because they are terribly allergic to them—a company has developed and is now selling allergen-free cats; they are rather pricey at present, but are sure to become more affordable in the years to come. To increase their value as the perfect home decorations, some South Korean scientists announced a few years ago that they had bioengineered a fluorescent cat that attractively glows in the dark. And to maintain continuity in their relationships with animals that unfortunately rarely live more than fifteen or twenty years, people now can also pay large sums of money to have their cats cloned, so that they can effectively enjoy the company of the same cat throughout their lives.

In contrast, I am not aware of any parallel efforts to develop scientifically-improved dogs—say, dogs that would use a litter box or dogs with an added instinctive desire to keep themselves clean—probably because practical-minded scientists, in light of all of the issues I have raised, suspect that there would be in the future little profit to be made from such projects. Indeed, the major focus of the current research I have heard about is not to improve dogs, but rather to replace dogs—with robot dogs, which can provide needed companionship without the liabilities of biological dogs, since they do not have to go to the bathroom, and since they can be turned off whenever their activities would be problematic. Common enough in science fiction as to be satirized in Woody ALLEN's Sleeper (1975), robot dogs of several varieties can now be purchased and are becoming better and better at emulating the real things. (I believe they are especially popular in Japan.) Yet, I know of no efforts to build robot cats—probably because, I would argue, scientists recognize that cats will fit right in to our futures, so that no artificial substitutes will be required. Thus, the evidence could not be clearer that the scientific community, by and large, has reached the same conclusion as science fiction—that cats are better suited than dogs to be integral members of the human households of the future.

I trust it is clear that I am not calling upon people to abandon their dogs, and I am not predicting that dogs will become less common in the future. People have long demonstrated a willingness to cling to customs and beliefs that most would regard as relics of the past, such as tattoos and astrology, and many people will probably still want to have dogs even while inhabiting the sorts of futuristic environments where, I have maintained, dogs would be incongruous. All I am asserting is that, when science fiction writers build future worlds with advanced technology, they characteristically sense that dogs would not really belong there, for the reasons outlined above, and hence tend to omit them from their stories. Whether people will ever respond to their deductions in the real-life decisions they make about household pets is another question altogether, and one I am not qualified to answer.

As a final thought: if science fiction writers have indeed taken sides in the ancient debate between cats and dogs, one might fault them for a failure of imagination since they so rarely consider another alternative: the emergence of a new sort of pet that might, in some situations, be even more appealing than a cat or dog. These could include an existing animal newly popularized as a pet—like the bush baby requested by Heywood R. Floyd's daughter in the film 2001: A Space Odyssey (1968); a bioengineered modification of a terrestrial species—like the mutated cockroaches that serve as space pets in Bruce Sterling's "Spider Rose" (1982); or an alien creature introduced into human company—like the Martian "flat cats" in Heinlein's The Rolling Stones (1952) and their cousins, the tribbles, in David Gerrold's Star Trek episode, "The Trouble with Tribbles" (1967). The relative paucity of such examples, and the ubiquity of cats, indicates that science fiction writers, even while creating bizarre new future worlds, can also be stubbornly traditional in their ways of thinking, forever devoted to old friends and unwilling to transfer their affections to new friends. And in this respect, they ironically resemble dogs more than cats.