One of the biggest questions facing humankind today—at least among those of us who were raised on science fiction and still concern ourselves with its propositions—is whether we humans are alone in the universe. And from that come a number of subsidiary questions: What will beings from another world look like? Will they be friendly explorers and traders or raiders and plunderers? How will we deal with them?
Science fiction has been divided on this issue. Everyone assumes that any self-aware entity able to cross the voids between the stars will have certain characteristics. They will be at least as intelligent—able to think and plan, use technology, identify and solve problems—as we are and probably more so. They will have power sources greater than ours and a technology likely more robust than ours. They will have a reason for coming here. And if they have any reason to bother with visiting humans on Earth, then they will have physical requirements based on conditions of gravity, atmosphere, and temperature—at the very least—which are similar to Earth’s. This tends to rule out giant space slugs that are born inside nebulae and travel between the stars naked to the vacuum of space under their own kinetic thrust. It also rules out vaporous membrane creatures who might be more at home in the swirling atmospheres of Jupiter and Saturn, or ice-crystal beings that would feel at home on Europa or Titan or out among the Oort Cloud.
But that still opens a lot of territory. H.G. Wells’s War of the Worlds proposed “vast, cool intelligences” in octopus-like bodies. Robert A. Heinlein’s Starship Troopers proposed arachnoid “bugs” with hive-like organization. Note that most of these representations are still drawing on elements of terrestrial anatomy: octopi that live in air rather than water, and spiders with human-scale intelligence or greater in bodies larger than ours.
Much science fiction, and especially that appearing in movies and on television, presents alien life forms born on other planets as basically humanoid. The invaders—because most of the encounters are hostile—are about our size and weight, move upon independently functioning limbs, have sensors clustered on one side of their brain cavities, and manipulate their technology with something approaching hands or paws or claws. And, of course, there’s the Star Trek universe, where everyone’s a humanoid of some description, usually identified by minor anatomical anomalies and skin coloring—things that can easily be applied in a makeup chair.1
Positing aliens as near-human is a useful plot device. It means that human readers and viewers can identify them as “the other” without guilt: close enough to human to be intelligible as evil-doers, but not so close that they deserve our respect and pity. In an age when we’ve finally realized that characters like Geronimo and his red Apache tribesmen, Shaka Zulu and his implacable black warriors, or Fu Manchu and his devilish yellow henchmen are genetically first cousins to the white Europeans who oppose them, and so should not be dismissed and demonized, we still need enemies that our fictional heroes can mow down with distain. Klingons, Romulans, and Cardassians will do for now. And when those humanoids have all been civilized and read into the Federation, there will always be zombies.
We’ve come a long way in the last two hundred years or so. Not only have we finally, officially recognized humans who have different habits of dress and hygiene, not to mention unusual religious and family lives, as basically the same as ourselves. We have also come to understand that we are not so different from this planet’s animals as well. Once we thought that any creature not capable of human speech, thought, and writing—that is, any animal—was inherently different from humans. We domesticated dogs, horses, and elephants but felt free to beat and kick them. We hunted whales for their blubber because it made good lamp oil. Yes, certain religions made icons of cats and jackals, monkeys and elephants, and granted to certain of their characteristics a human-like godhead. But we knew they were essentially different. We believed that humans, with our capability of self-recognition and self-awareness, with our ability to divide time into past, present and future—whereas most animals are presumed to live in an eternal now—and with our sophistications of language, writing, trade, and technology, were not just more advanced than the animals but intrinsically different. And better. We have immortal souls.
It was only in the last hundred years or so that we began to recognize intelligence as a spectrum. At one end are the single-celled creatures that can sense and react to a light source and avoid areas of damagingly high or low pH. Along about the middle of the spectrum are creatures like cats and dogs that can hunt for themselves, care for their young, groom themselves, sense danger, seek advantage, and perform other rudimentary survival tasks. Finally, out towards our end are creatures like the great apes that communicate in complex ways, use available tools to dig out food, set traps, and pass rudimentary discoveries from one individual to the next. And then, still on this scale but on the near end at the highest level of development, are the wondrous human beings, who speak in complete sentences with complex verb forms, wonder about the stars, build radio sets and rocket ships, and stand halfway to being angels and gods ourselves.
We still don’t know exactly what the family dog is thinking, but we assume that when it wags its tail and licks our hand, it’s certainly showing respect, possibly gratitude, and perhaps even the bonding of love. Many of us can read the shape of our dog’s mouth and just know that it’s smiling. We still can’t understand the language of dolphins and whales, but we sense a complexity in those repeated whoops and clicks that must be meaningful at some level. We can read the dances of bees and marvel that those tiny, hard-wired brains can send and receive such complex and pertinent messages.
But we are still limited in our appreciation of the senses. Most of us haven’t quite grasped that for many animals, sound and vocalization are not the mainstay of communication. Dogs read more complex messages about their world in scents than in barks. Bats see better with their ears, by echolocation, than with their eyes. Octopi and creatures living deep in the ocean communicate with colorful light shows that rival the marquees of Las Vegas casinos.
And yet these are all creatures with whom we share a basic chemical nature. I once suggested,2 that because every living creature on Earth shares the same DNA/RNA/protein coding mechanism, with no apparent evolution—that is, no competing systems left lying around that might use different chemicals or a different arrangement of the codons, suggesting evolved alternatives or experiments that once were tried and failed—then perhaps this complex DNA-based system actually developed somewhere else in the cosmos and either drifted into our solar system at the bacterial level, or was seeded here on purpose, or was left by accident—the “astronaut’s glove” hypothesis.
If life here on Earth is the product of some kind of bacterial seeding program, then we might meet our first aliens as some kind of distant cousin. They might be chemically similar to us. But their forms—the evolutionary branchings which on their native planet, with its own unique conditions, had chanced to arrive at superior intelligence and technical capability—might be no more similar to us than a tube worm or a turtle. All we can know by applying logic is that any cell-based life form would need to attain a certain size, a certain level of differentiation among its component cells, a level of complexity in their cohesion,3 and an expressed energy level that enables it to develop interpersonal communication and cooperation, technological sophistication, and the will and desire to travel which would enable them to cross the voids between the stars.
But if the DNA/RNA/protein system is unique to Earth, if any competing chemical systems have simply disappeared because the DNA system that won is so superior and the chemistries that lost simply dissolved in the rain, then all bets are off. Space-faring aliens would still need a level of complexity in cohesiveness and a level of energy expression to make complex decisions. But their organizing codons might be based on silicon chemistry rather than carbon chemistry. Their energy might come from breaking arsenate bonds rather than phosphate bonds. Or they might use some completely unique form of chemical organization. They might exhibit bizarre physical and mental characteristics and capabilities—or deficiencies—undreamed of in terrestrial life forms.
We might not be able to communicate with such aliens, given that we cannot yet communicate at any detailed level with our nearest carbon-based relatives, the great apes, dolphins, and whales. We might not even be able to recognize their motivations, let alone assign them any kind of morality, where discovery and trade equate with “good” and “benign” activities, while extermination and plunder equate with “bad” and “hostile,” just as we have a hard time assigning motivation to viruses, algae blooms, termites, and army ants. We might not even recognize these bizarre aliens as being alive.
The universe is a vast and varied place. We can expect to see signs and wonders. But we have to keep our eyes and ears, not to mention our imaginations, open and questioning. And after all that, wouldn’t it be disappointing if the first alien race we encountered were Vulcans with pointy ears, sugar-bowl haircuts, and a tinge of green makeup about their eyes?
1. I believe the producers once floated the idea—although I don’t have a reference for it—that all of these humanoids derived from a single strand of DNA that had scattered throughout the near quadrants of the galaxy and only later evolved these minor physical alterations on each world. This ignores the vast chemical similarity of human beings to all other life forms on Earth and our anatomical similarity to most land-based animals of the phylum Chordata.
2. See DNA is Everywhere from September 5, 2010.
3. Think of all the chemical signaling back and forth that allows various kinds of cells to function as a whole. For example, to initiate a simple process like blood clotting at a wound site requires a twelve-step cascade and interplay of various molecules so that the amount of clotting is proportional to the amount of damage.