by Quentin Long ©2008 Quentin Long

   Communication: It’s something that pretty much any sentient species is going to have to do. Of course, that doesn’t mean any two sentient species are obligated to communicate in the same manner!
But however a given critter goes about it, communication involves copying concepts/ideas from one mind to another. And since direct mind-to-mind thought-transference (i.e., telepathy) isn’t a viable option, that means encoding said concepts/ideas into a set of symbols in a physical medium of some kind, bringing those symbols to the attention of another sentient, and letting that sentient decode the symbols.
   In the case of the species homo sapiens, one could argue that the primary mode of communication is complex patterns of acoustic vibrations generated by a specialized set of bodily organs—that is to say, spoken language. From an engineering point of view, sound has a lot going for it as a medium for communication; for one thing, making noise is cheap (in terms of energy-cost) and easy. Sound being omnidirectional, sonic-based communication doesn’t require precise targeting on the part of either the sender or the receiver. It’s versatile, being equally suited to communicating with one sentient privately or a whole mass of sentients collectively. The bandwidth of sound—its information-carrying capacity—ain’t so bad, either! And note that us humans are far from the only species that exploit sound for this purpose; think of bird song, wolf howls, whalesong, etc.
   All in all, it’s a good bet that lots of sentient species will use sound as a ‘substrate’ for communication. Which isn’t to say that it will necessarily be easy for two sound-using species to comprehend each other’s sonic communications! If Species A can’t even hear the noises with which Species B communicates (to cite only the most obvious possibility), that’s going to be a nontrivial obstacle to understanding. As well, keep in mind that communicating must necessarily involve some sort of scheme for associating concepts with symbols; all such schemes are fundamentally arbitrary, which means none of them can be deduced from first principles. Which, in turn, means it’s quite possible that even if Species A can hear the noises Species B makes, they may not recognize those sounds as a form of communication!
   Naturally, sound isn’t the only possible communication-substrate. Light can also serve. For sentients that live on a planetary surface, there’s plenty of electromagnetic radiation to exploit; for critters whose environment has little-to-no ambient illumination (i.e., caves, deep sea, etc), light-emitting organs can be a viable option. Mind you, light may not be as good a choice as sound. To generate sound, all a critter really needs is a physical body; to generate light, a life-form needs some sort of biochemical system that’s specialized to do exactly this thing. And while light-based signals may have a near-infinite maximum range, sound-based signals aren’t blocked by smoke, haze, fog, or solid matter…
   In homo sapiens, visual communications includes American Sign Language, gestures, and the written word. Since these options work for us, they’re obviously live possibilities for other species, too. However, they aren’t the only forms of vision-based communication that might be used! Many creatures can alter their general appearance, for instance by making their fur (or feathers) stand on end so they look bigger than they actually are. If you’re a non-sentient critter, you might do this as a ‘threat display’, to discourage other animals from attacking you. But if you’re intelligent, sophisticated control of fur-raising might well become the basis of a form of communication.
   In this context, it’s interesting that fur isn’t necessarily a one-level thing; there can be longer ‘guard hairs’ and shorter ‘underfur’. Depending on how fine-grained a creature’s control over its fur is, this means fur-raising could conceivably let that creature display three different colors! With all hairs down, you see only the guard hairs; with only the guard hairs raised, you can see the underfur; with all hairs raised, the creature’s actual skin-color becomes visible.
   And then there are critters like the chameleon and octopus, which take color-changes to the logical extreme. If one of these species had intelligence, is it really so implausible to think that its members might use organized color-patterns to express their ideas, just as we humans use organized sound-patterns for exactly that purpose?
   The senses of smell, taste, and touch are not well-suited for use as bases for communication. Touch and taste, in particular, are very short-range; communication based on either of these senses would pretty well require being in close physical contact all throughout the entire ‘conversation’. Nevertheless, if you’ve got a ‘perfect storm’ of exactly the right combination of environmental factors and evolutionary history, it’s at least conceivable that an intelligent species might use a smell-, taste-, or touch-based mode of communication. If you’re thinking about creating such a species, keep in mind that the aforementioned ‘perfect storm’ has to explain how come your species managed to avoid developing sound- or vision-based communications.