The most historic moment in mankind's history had finally arrived: the first face-to-face meeting between human and alien.
Her expression inscrutable, the President of the Global United Nations waited as the spaceship descended. All heads of nations were in attendance, crowded into the purpose-built amphitheatre. Hundreds of film crews jostled for space in media sections. Security and military personnel, strategically-placed, patted their weapons nervously.
The alien appeared at the spaceship entrance. Thousands present, and billions watching on every available interface around the world, inhaled. A quadruped, the size of a calf, with a snake-like neck and thin, long snout walked slowly down the ramp and up the red carpet to the waiting President. She smiled warmly and extended a hand. No one breathed.
The alien paused, then walked behind the President. Confused, she turned to face it. Security gripped their guns. Once more, the alien walked behind the President. She spun round again, looking anxiously towards her cultural advisers, who were huddled in a group, whispering. The alien hesitated and looked back towards its ship. Seemingly resolving to give it another try, it walked quickly behind the President a third time. Finally, the penny dropped (this woman wasn't head of the Global United Nations for nothing). The President bent forward and parted her cheeks. Relieved and pleased, the alien delicately sniffed her behind.
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Science fiction tends to assume that intelligent extra-terrestrial beings are not only likely to be humanoid, they're also likely to communicate as humans do, through speech. And also, miraculously, in English, in the same way that many English-speaking tourists believe that wherever you go, someone's bound to understand you, providing you speak slowly and loudly enough.
Our reasoning behind our assumption is weak: we're an intelligent species, and we communicate through speech, so probably another intelligent species use speech, too. While for the foreseeable future we're unlikely find out for sure, we only need look around at other species for some ideas as to the possibilities.
One reason humans evolved to use sound as a communication medium is because, with its wide frequency and volume range, sound can hold a large amount of information, so it makes sense that highly intelligent aliens with lots of information to convey might use sound, too. But there's no particular reason they should speak as humans do, by exhaling through vocal chords, then shaping the formed sound with throat, tongue and lips. Many animals produce sound using other body parts, rubbing, banging, vibrating or rattling themselves to convey meaning.
Grasshoppers, for example, rub a rasped leg against a wing, and woodpeckers drum nearby resonant objects. Cicadas signal their presence using a pair of ribbed membranes at the base of the abdomen, some species achieving volumes higher than 120 dB, loud enough to be painful to the human ear.
As sound travels four times faster in water than in air, perhaps the alien life forms we encounter will be aquatic and make noises similar to baleen whales. Unlike toothed whales, such as dolphins, baleens don't need air to make sound, and produce it in some as yet unknown way, probably using their larynxes.
Or perhaps the aliens will click as plants do. Another sound that originates in some mysterious way, plants signal to each other by clicking through water in soil, possibly to warn of threats.
If we're fortunate enough to encounter another sound-producing species, our difficulties could still just be beginning. Without technical backup, our hearing capabilities are severely limited. We can't tolerate the loudest cicada, and plants' clicks are far too quiet for us to hear. We can't hear many whale songs because they're pitched too low and bat squeaks are mostly too high. So while we could probably cope with an alien talking to us by rubbing his appendages together, any sound production out of our hearing range would kill the dream simply conversing with aliens as humans do.
Many science fiction writers seem to expect aliens to communicate through spoken language (and just one language for their entire world) but as humans we find ourselves handicapped without accompanying visual information. Although we think we communicate mostly through speech, visual cues hold lots of information. Facial expression, posture, gesture, eye contact, proximity: all of these nonverbal signals are highly significant to us. Some researchers estimate between 60 and 70% of meaning is conveyed non-verbally.
We're by no means alone in this. Body language is very important to many other species. Every dog owner knows the 'lets play' posture, and the beg stare. Every cat owner has been tripped at least once while opening a can of cat food. Maybe the first aliens we encounter will communicate important information physically, too. Maybe they will, like the cockatoo, wiggle their tongues in pleasure when they see something they like; or maybe they will, like the llama, stamp their foot in warning before striking. Assuming they have tongues or feet, that is.
Sight communication isn't limited to body language, however. Nocturnal aliens could easily have evolved light signaling. Light, like sound, has a high information-carrying capacity, and light languages are not only possible, they already exist. The dots and dashes of Morse code are easily conveyed by flashes of light, and were used extensively in shipping in the recent past.
Many Earth species have developed ways of generating their own light. Fireflies are the obvious example, and their use isn't limited to simple mating signals. Female Photuris fireflies mimic a different genus, Photinus firefly flashes in order to entice males close enough to eat. They need a certain chemical in Photinus blood to help them repel predators. As they say, fact is sometimes stranger than fiction.
If we must use sight to understand our first-encountered alien species, we are, as with hearing, at a disadvantage. As predatory animals with our eyes at the front of our heads, our field of vision is limited to roughly 200 degrees horizontally and 135 degrees vertically, decreasing with age. By contrast dragonflies have a 360 degree field of view.
In terms of visual acuity, humans are also far from an exemplary animal. That title probably goes to birds of prey, which can see much more clearly and much farther than us. The Bovea buzzard, for example, can see 6 to 8 times as far. Humble chickens and budgerigars can see light flicker up to 100hz, while we see anything faster than 50 Hz as continuous.
Our color and light intensity perception are also woefully inadequate. We have only three types of color cell receptors in our eyes. The mantis shrimp has 12, enabling it to see ultraviolet, infrared and polarized light, and compared to nocturnal animals we're effectively blind at night.
If those aliens are indeed 'flashers' of information, we will probably need more than our eyes to perceive their signals.
If humans are at a disadvantage in sight and hearing, we're virtually disabled when it comes to the other senses. We use touch to communicate to an extent, and we detect air-borne chemical signals more than most of us are aware, but to understand aliens that use touch or smell extensively we'd require supplementary equipment. If we were as talented as bears, that can detect a dead body twenty miles away and smell 2,100 times better than humans (with their noses), or like manatees, entirely covered in hairs so sensitive they gather information without actually touching anything, we might stand a better chance.
Communication through touch, taste and smell might seem unusual to us, but few things are further from our experience than electrical signaling. This may have been one of the earliest forms of communication in Earth's evolutionary history. Life on Earth began in the ideal medium for electrical signaling, water, and most species using electricity to signal are ancient lifeforms, such as amphibians, sharks and monotremes. Interestingly, the aquatic monotreme, the duckbill platypus, has far more electroreceptors than the two species of echidna that make up the rest of the order. Echidnas use their electroreceptors in moist soil but it's thought the cells are mostly a hangover from an aquatic past.
The commonest use of electricity in aquatic species is electrolocation, used to navigate and hunt in murky water. But weakly electric fish also use electrocommunication, modulating the electricity they produce, for mating, territorial displays and as a form of aggression. Several Earth species, most notoriously the electric eel, also use electricity as a weapon.
Air, however, is a terrible conductor of electricity, so any alien communicating with us as electric fish do will find their messages falling on deaf ears. For aliens to communicate with us through electric signaling they would need to touch us. This seemingly unlikely method was recently found to possibly be the case with bees and flowers. Flowers generate a weak negative charge, which changes whenever a bee lands on them. Is the flower signaling to the bee? Perhaps, as bees have been shown to be able to detect the charges, and it would help both organisms if flowers were able to give information about their nectar reserves.
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As these examples illustrate, the subject of alien communication isn't well served by writers who confine their imaginations to human-like speech, but there are good reasons for science fiction authors not to deal realistically with the question. Aliens communicating through flashes of light, exudations, or complicated posturing would get in the way of most stories. We mostly want to know what the aliens are saying, not how they're saying it. Behavior similar to that of slime molds, which give off chemical signals to find each other, then coalesce into an autonomous multi-cellular being, is a story in itself.
On the other hand, the subject is a rich vein of possible world-shaping and plot devices. Imagine an invading alien species' elation on finding out their communications are undetectable and utterly incomprehensible to humans. Or, conversely, a species that can survive but is unable to communicate in Earth's environment.
Perhaps the main reason science fiction authors don't tend to explore this thorny subject is very straightforward: we may be interested in the future and the unknown, but we also read science fiction to find out about ourselves. We identify with human characters, or aliens with human traits. When we read about aliens that are truly other-worldly, what we want to know is how we interact with them, and what the story tells us about ourselves.
Think back to the beginning of this article. Whose mind were you in as you were reading? Were you imagining how the alien felt? Did you think it was confused, worried and frightened that this new planet's primary species would attack it? Or were you identifying with the main human in the piece and her bewilderment? Were you thinking about what you might do in her place?
If ever we are contacted by extra-terrestrial beings, one thing's for sure, we'll need to start thinking outside the box.
For further reading on alien life forms, try this article aboutslime moulds.
Or about the electrical communication of flowers and bees.
Or the private conversations of plants.