Aliens, Where are they? The Alien in Our Minds by Larry Niven

The only universal message in science fiction is as follows: There are minds that think as well as you do, or better, but differently.

They don’t have to be interstellar visitors. They could be the next generation of computers or computer programs. They could be apes or dogs or dolphins after we’ve fiddled with their brains. They could be human beings shaped by a strange environment, or altered by genetic experiments, or mutated, or given new tools such as computer implants. I tend to concentrate on aliens, but you should remember the other possibilities.

I intend to convince you that the human species is the destined ambassador to a respectable segment of the universe. There are reasons why the ETIs, the extraterrestrial intelligences, haven’t come visiting. We will have to go to them.

There is something out there that thinks as well as you do or better, but differently.

The question is: why do you care?

I’ll stipulate that you as readers are not a random sample of the population. Our common interest is in aliens; and that’s a remark­able thing in itself. But the entire population is interested in alien modes of thought. I’ll prove it.

1. First Martian expedition. The ship lands on its fins near a canal and finds Martians waiting (this is an old story).

They discuss philosophies, technology, biology ... sex. A married pair of astronauts demonstrate human reproduction for a Martian audience.

“That was fun to watch, but where’s the baby?”

“Not for a third of a Martian year.”

“Then why were you in such a hurry at the end?”

2. Robert Sheckley. All computers are linked to one tremendous artificial mind, all across the world. They ask it one of the harder questions: “Is there a God?”

“Now there is a God.”

From a short story in a magazine, this became a common joke in oral tradition.

3. David Brin on dolphins. No, they’re not intelligent. Audi­ences get mad when he tells them that. We want to believe that anything that likes us that much must be intelligent.

Humankind’s ancient fascination with aliens is built into our genes. There’s evolution at work here. Meeting aliens has been a normal thing for humankind. For most of human history, successful tribes have numbered about a hundred, maybe less, if something went wrong. More than a hundred, the tribe had to split. Hunter- gatherer groups need lots of territory, and they have to move fre­quently.

A hundred thousand years ago, or a million, all humans were hunter-gatherers.





There were strangers around. A wandering tribe may have stumbled across something different, with odd, ugly faces, bizarre customs, strangely colored skin.

Or they may have stumbled across us!

People who couldn’t make themselves deal with aliens had to fight when they met.

People who could had their choices. They could trade, they could make agreements including treaties, they could postpone a fight until they had the advantage, or they could set rules for war that would allow more survivors.

We might also consider that a man who can talk persuasively to aliens can also talk persuasively to his own tribe. A persuasive speaker was likely to become the chief.

But even without the external aliens, there were aliens internal to the tribe.

We are a species of two intelligent genders. Men and women don’t think alike. People choose their mates: they breed each other for certain traits.

Adults and children don’t think alike. Successful human beings talk to their children. They teach their children to become successful adults. Where the generation gap is too great, the tribe or family doesn’t survive.

We have dealt with alien intelligences for all of the time that humans have had human brains. At first blush, the same would hold for any extraterrestrial intelligence. But aliens may have been forced into other paths, paths that don’t force negotiation upon them.

Parthenogenesis, for instance. Budding instead of sex: no oppo­site gender.



Children might have no intelligence. A child’s brain might be the last thing to develop. Or the children might hatch from eggs and have to fend for themselves. An adult may never see a child until a young adult comes wandering back out of the wilderness. There would then be no intellectual contact with children.

Aliens may have radically divergent genders (as with most in­sects). If one sex is nonsapient, there is no negotiation.

There may be a mating season. That’s common enough on Earth, but look at the result. In mating season, both genders might lose all intelligence. Intelligence might be a handicap as regards breeding, even for us, from the evolutionary viewpoint.

An intelli­gent being is likely to think of reasons for not mating with an avail­able partner, or for not having children just now, or at all.

But in a genuine mating season, male and female do not negoti­ate before they mate. Males may negotiate, but two males butting heads are very much alike. You might picture the elders of one gender arranging matings for the younger ones prior to the mating season. This could be done using cages. Lock ’em up together.

Humankind has been fiddling with reproduction for a long time. Before “the pill,” there were abortifacients and French letters and the rhythm method. Technology may supplant our present modes of reproduction. War between sexes finally becomes a real possibility. One gender exterminated, cloning for reproduction from then on, and a depressing similarity among individuals.

Do you see the point? We assume that an alien intelligence will want to talk to us.

Or to someone! But it ain’t necessarily so.

Where are they?

It’s the most interesting question now being asked. The universe is far older than the oldest known intelligent species. Why haven’t they come visiting?

I tend to ignore the evidence for flying saucers. None of the testimony is very plausible; and even if you believe it, or some of it, you still don’t get interstellar cultures. Close Encounters of the Third Kind was faithful to what we hear of them. The movie showed its aliens behaving in just the whimsical, senseless, irresponsible way that the flying saucers always have. There’s no intelligence here. It’s easier to believe in some unknown kind of mirage, or in a space-going animal that occasionally dives too deep into an atmosphere and gets itself killed.

We can postulate an interstellar commonwealth that has been ignoring Earth or has made Sol system into a zoo or national park; but it won’t wash. The kind of power it takes to cross interstellar space is difficult to ignore. Any decent interstellar reaction drive must convert more mass to energy than the mass of the payload; you have to get up to at least a tenth of light speed and back down! There would be side effects on a cosmic scale. For laser-augmented light- sails, the same applies.

We would have seen something... something as powerful as the pulsars, which could have been interstellar beacons until we learned better.

How long does it take to make an intelligent space-going spe­cies? Our sample case is Sol, Earth, and the human species. We’ll stick with our only sample and generalize from there.



Our sample is a world big enough to hold a thin atmosphere, orbiting within the liquid water domain of a yellow dwarf star. If we want an oxygen atmosphere, we must wait for the life forms to develop photosynthesis. Therefore, our first approximation is that it takes four and a half billion years for a planet of this specific type to produce thinking beings.

The human species seems to be within a thousand years of reaching across to the nearest stars. Could be a hundred, could be ten thousand, it’s still a comparatively short time.

Keep in mind that other chemistries may form other kinds of life. Nothing in our temperature domain works as well as water and oxygen and carbon. In hot environments, chemistries are probably too unstable. Within the atmospheres of gas giant planets, there are conditions that might give rise to organic life. But escape velocity is very high, and what would they have for tools? In very cold condi­tions, on Pluto or Titan, or in the oceans beneath the icy crusts of some of the moons of Jupiter and Saturn, there may be exotic chemistries that can support life. Then again, chemical reactions happen slowly at such temperatures. We might have to wait longer than the present age of the universe.

We can stick with our sample and not be too far off.

Four and a half billion years. Look again and the number goes up. We need materials to form a solar system. We need gas clouds, gravitational fields, heavy elements, and shock waves from stellar explosions. We need a galaxy. Before that, a universe.

The solar system condensed from a relatively dense interstellar cloud. That cloud contained supernova remnants, the materials that became the cores of planets and the elements of our bodies. The event that caused the condensation may have been a shock wave from a supernova explosion. We need to allow time for previous supernovas and time to make a triggering supernova; but a super­nova doesn’t take that long. Small stars don’t go supernova. Large stars burn fast. If we start with a star much larger than Sol and wait a billion years, it will explode. The shock wave comes through and flattens the near side of the cloud. There’s gravity and there’s turbu­lence. Vortices analogous to whirlpools or dust devils form in the cloud. Some of them collapse into bodies massive enough and hot enough to support fusion.



The galaxies formed near the beginning of the universe.

Supernovas have been occurring since a billion years afterward, and they still happen. It’s fair to assume that it takes seven billion years to make an intelligent species.

The universe is generally estimated as fifteen to eighteen billion years old. Atoms formed after the first half-million years. The first stars were big and unstable. Call it two billion years to spread supernova remnants through the environment. The first intelligent species must have evolved seven to ten billion years ago. Based on our own sample, they began exploring space almost at once: say, two or three million years after the taming of fire. Somebody should have been expanding through the universe for up to ten billion years. There should be at least hundreds of thousands of them. Any success­ful industrial species may have gone past the Dyson sphere stage into really ambitious engineering projects.

We’re alert enough to recognize Dyson spheres now!

Where are they?

Something’s wrong with our assumptions.

Maybe our number is wrong. Maybe it takes eighteen billion years for a monobloc explosion to produce intelligent beings. We can be pretty sure it isn’t nineteen.

We can postulate events that regularly destroy an intelligent species before it can reach out to Earth. What follows is likely to be depressing. Hang on. There are answers you’ll like better.

Intelligences may tend to destroy the ecological niche that pro­duced them. We do tend to fiddle. The Zyder Zee is still the world’s biggest successful planetary engineering project, but the Sahara Des­ert seems to have been caused by goat herding. Rabbits in Australia, garden snails in Tarzana, were imported for food. Mongooses were introduced to Maui to deal with snakes and rats. Unfortunately, rats are nocturnal and mongooses aren’t, and there’s easier prey than snakes. The fine for feeding them is $500, because they’re wiping out species that will never again appear on Earth.



I was on Maui recently. Mongooses are cute. They like potato chips.

We fiddle with life forms too. Broccoli is a recent invention, but there are hundreds of breeds of dogs shaped over tens of thousands of years of fooling around. It’s a simple technique: what you don’t like doesn’t get to breed. But now we know how to fiddle with genetic coding. What are the odds of our making one irrecoverable mistake in the next thousand years?

Destroying one environment in this fashion wouldn’t extermi­nate us if enough of us had left the planet. But the energy considera­tions are worth looking at. Dogs were shaped by primitives who used the wheel if they were wealthy enough. Modern biological experi­ments can be run for millions of dollars, or less. A decent orbiting habitat might be built for hundreds of billions. The odds are that your random ETI had genetic engineering long before he ever left his planet. Where are they? They made one mistake.

Nuclear war could certainly destroy an environment if it’s done right. A war fought with asteroid strikes would be even more terrible, but we need not consider these. Such a war would imply that our ETI already has the means to build a habitable environment somewhere else.

A local supernova could do the job. The world need not be wiped clean of life. A good many species would die or change, including the most complex.

The aliens’ primary star may turn unstable.

There’s evidence for cycles of destruction on Earth, spaced around twenty-six millions years apart. Catastrophic events may occur more or less regularly in the cores of galaxies. Or there could be something dangerous, some very active star or star system, orbiting the galactic axis a little out or a little in from our own orbit, so that Sol system passes it every twenty-six million years.

Then there’s Nemesis, a hypothetical massive body in a twenty- six-million-year orbit around Sol. At its nearest approach, it disrupts the orbits of a great many comets. Some are flung to interstellar space. Some drop into the inner solar system. For the next million years, comets divebomb the planets, and a few of them hit. The nucleus of a comet is nothing you want to stand in front of. Read Lucifer’s Hammer, then multiply the numbers by a thousand.

We know that the Earth gets hit somewhat regularly by a giant meteoroid impact. Every twenty-six million years, life on Earth signals that something horrible has happened, by dying. The event that killed the dinosaurs also wiped out most of the life on Earth, and half the species.

What are the odds that a comet or asteroid will intersect some random inhabited world during that brief period after fire and before the ETIs can get off the planet? In a three-million-year period, our own odds are not terrible; but our own situation may be relatively benign.



So much for natural causes.

If you like paranoia, you’ll love the Berserkers. Fred Saberhagen and Greg Benford have different versions, but both involve self-replicating artificial intelligences. Saberhagen’s version is space-going forts left over from some old war, and they’re pro­grammed to destroy all life. Benford’s version was built by old artificial intelligences, and they fear or hate organic intelligences. If the Berserkers are out there, we’re on the verge of attracting their attention.

These are the most pessimistic assumptions. But let me give you the David Brin theory before you have to go looking for aspirin.

We know of two ways that otherwise earth like worlds can go wrong. Venus was too close to the sun. Too much atmosphere was boiled out, and the greenhouse effect kept the surface as hot as a brick kiln. Mars was too small to hold enough atmosphere, and too cold. There’s evidence of liquid water on Mars at some time in the past, but there was never enough of it for long enough. Earth could have gone in either direction.

What about a third choice? Let’s look at an Earth that’s just a little larger. There’s just a little more water. Astrophysicists are generally happy if they can get within a factor of ten. How much land area would we have if Earth was covered with ten times as much water?

Even twice as much would be too much. Life would develop, we’d get our oxygen atmosphere, but nothing would ever crawl out onto the land because it wouldn’t be worth the effort.

We don’t actually need more water than we have. Let’s give Earth’s core a little less in the way of radioactives. The crust grows thicker, circulation of magma slows down, mountain building be­comes much rarer. We get shallow oceans covering a smooth planet.



Something might still develop lungs. A big-brained whale or air-breathing octopus might well develop an interest in optics. There’s water and air to show him how light behaves. He might even find tools for telescopes; but what would he do about the stars? He’s got no use for the wheel and no access to fire.

There are less restrictive assumptions that could still keep visi­tors at home.

Our still-hypothetical alien may have evolved for too specific an ecological niche. One lousy pond, or one lousy island, or the growing area for one specific plant.

Our ETI may not have the means to conquer large parts of a planet, let alone venture outward. This is certainly true of thousands of earthly species. Even where some rare species has spread throughout the world, it is usually done by differentiation of species.

And it was done slowly. Our ETI may be subject to biorhythm upset. Even where a planet has been conquered, there may be no contact between parts of it. No airlines, no ships, nothing that moves faster than the speed of a walking alien, because jet lag kills.

A set of ETIs who have conquered their planet and are already suffering from population pressure may not even be able to breed with each other, let alone gather for a summit meeting. On the other hand, they won’t have extensive wars of conquest either. An invad­ing army would be dead on arrival.

Where are they? Why haven’t they come? By now, we can see a number of possibilities.

Something’s killing them off. It may be natural or artificial. Or they may inevitably kill themselves off.

These are the pessimistic assumptions, and they imply that we too are doomed.

The sky may be dense with water worlds, a thousand of those for every earthlike world where land pokes through. But water worlds don’t allow a technology that would lead to spaceflight. They might allow telescopes and guesswork about other kinds of life. Intelligent whales and octopi may be waiting for us all across the sky.

The ETIs may have no interest in talking to aliens. Even where the interest can be generated, there is not the skill for dealing with other minds. The evolutionary basis for that skill may be unique to humankind.

As indicated, the aliens may have adapted too specifically to their ecological niches, or they may suffer from extreme biorhythm upset. It is, in fact, most unlikely that a species evolved in earth like conditions would be suited for space.

We’re beginning to find those limits in ourselves.

We lose something if these guesses are right. We lose the Draco Tavern and the Mos Eisley spaceport. We lose all of Star Wars. We lose Ensign Flandry and Nicholas Van Rijn and the Kree-Lar Galac­tic Conference. The only interstellar empires left to us are all human: Dune, and Foundation and Empire, and Jerry Pournelle’s Codomin­ium and Empire of Man before the Moties were found.

But we lose all conflict, too, until interstellar war can be waged between human and human.

What’s left? The picture is peculiar precisely because it was so common in science fiction forty years ago. Human explorers cross interstellar space to find and communicate with native wogs. Mis­understandings with the natives may threaten ship and crew, but never Earth.

Water worlds are not a problem. Floating bases could be estab­lished. The water dwellers would not perceive us as competitors. Species restricted to one ecological niche would also pose no threat to us. On the contrary, they might have things to tell us or show us—art forms or philosophical insights if nothing else—and they would likely be glad of our company.

There is hope in the fact that dolphins like us.





As for aliens with no impulse to talk to us, we can give them reasons. We’re good at that. A space-going species has things to teach, to individuals who can make themselves listen. We’ve been talking to aliens for millions of years. If Ronald Reagan can talk to Russians, some among the four billion of us are capable of talking to Martians.












In: Aliens in the Anthropology of Science Fiction. Edited by George E. Slusser and Eric S. Rabkin. Illinois, 1986, pp. 3-12.