Alien languages may not be entirely alien to us

The 2016 movie “Arrival" portrayed scientists frantically scrambling to decode an alien language. Although the on-screen aliens communicated—and even thought—in a completely different way from humans, the hero played by Amy Adams of course eventually succeeded. But off-screen, alien language may be so, well, alien that we could never understand anything about it. How do we approach dealing with something so completely unknown that it may also be completely different from anything we might expect?

In fact, questions about the nature of possible alien languages are tractable. Language remains the lone thing that appears to separate humans from other animals on Earth. The comparison of human language with animal communication can help, should we ever frantically need to decode an alien signal. After all, aliens will have evolved their language on a planet that is, like Earth, also full of non-linguistic species. But what really is the difference between language and non-language?

As a first step, let us consider why we think that this essay is language but birdsong isn’t. Some birds sing incredibly complex and varied songs. The mockingbird, for instance, combines up to 100 different song types into long sequences that rarely repeat themselves. Can we really be sure that the birds aren’t speaking to each other? Or think of orcas (killer whales), which have a repertoire of more than 100 different calls. Might they be using their complex communication to talk?

These unanswered questions point us in the direction of how to decode alien language. Perhaps we could identify a telltale fingerprint of language—some kind of statistical test that would give an unequivocal sign that a particular signal from outer space was indeed an alien message and not just noise. Such a language test would also indicate whether pigeons are in fact talking about you behind your back: If their cooing passes the language test, that would indicate that they were truly saying something.

Yet despite the complexity of birdsong and whale song, animals don’t seem to have that much to say to each other. “Stay away from my territory," “Beware of the leopard" and “Come mate with me" sum up most of the messages we expect from animals. They could combine their sounds in almost infinitely varied ways, but they use just the tiniest fraction of these possibilities.

All communication—and, eventually, all language—has evolved slowly through natural selection. The honey dance of the bees; the twittering song of the starling; the ballet dance of the male manikin bird—all achieved their impressive complexity slowly. Natural selection has no foresight and no goal in mind, so the solutions that will be favored are those that best suit the problem at hand. Making many different kinds of sounds is useful—not because they lay the basis for a language but because messages can be clear and unequivocal. Animals have large repertoires as a side effect of their communication needs, not because they actually need large repertoires.

Perhaps grammar really distinguishes language from non-language. But many animals also have a grammar of sorts. For example, monkeys, with a fairly limited repertoire of sounds, combine those sounds in different ways to create new meanings. But as with the large repertoires of birds, this is just an evolutionarily efficient way of arranging sounds. Grammar seems to evolve as a byproduct and may not be necessary in animal or alien languages.

Consider the Caribbean reef squid, which creates swirling patterns of color on its skin using specially adapted skin cells. We know that squid communicate to each other using these visual patterns, but rather than having a complex structure in time (like a spoken sentence), these patterns are structured in a complex way in space, like a painting. No one can deny that a painting can convey a very complex message, but does it have grammar? Not really. What if aliens want to communicate with us by paintings? Would we recognize that as language?

It is difficult to find a truly general criterion—a fingerprint—for language, which considers possibilities as different as the song of the mockingbird and the flashing colors of the squid. But no matter how advanced an alien civilization is, it must have evolved from simpler life-forms that communicated in simpler ways. There are universal traits that evolution should favor in the emergence of any language on any planet.

The most important of these seems to be this: Language should be as complex as it needs to be to convey the necessary information, but no more. An infinitely complex language would mean that aliens would need infinitely large brains to process it. Evolution values efficiency, and absurdly complex language is inefficient. This principle applies equally well to humpback whale song and to Michelangelo’s paintings: We can understand the meaning in a painting’s beauty because it is balanced, not because it is complex.

Such a principle should apply to an alien’s language too, and hence to their messages to the people of Earth. Even if an advanced civilization decides to restructure its language to be more regular, as humans have done with Esperanto, it is already too late. Our brains have been shaped by our language as much as the other way round, and Esperanto still carries with it the traits of its earlier, less well-structured predecessors.

Quantifying this evolutionary balance between complexity and simplicity turns out to be relatively easy, since there is a mathematical continuum that runs between randomness and regularity. Human language seems to be perched precisely between complexity and simplicity, but most animals are way off to the sides. Birdsong—beautiful though it is—is far too repetitive and stereotyped to be language. Listen to a bird, and you will hear the same phrases being sung over and over; humans rarely speak that way, unless they are hawking wares on street corners.

Must alien language obey that same balance? We can’t be sure. But if we know anything about aliens, it is that they will have evolved on their planet through evolution by natural selection, just like we humans did. The aliens’ distant ancestors surely howled and hooted, tweeted and snorted (or did the alien equivalents) almost meaninglessly, just like our own ancestors. So their languages may well have inherited that fundamental fingerprint, just like our own. This offers us an excellent starting place to begin the frantic scramble to decode alien messages—should we ever receive any.

—Dr. Kershenbaum is a zoologist at the University of Cambridge. This essay is adapted from his new book “The Zoologist’s Guide to the Galaxy: What Animals on Earth Reveal About Aliens—and Ourselves," recently published by Penguin Press.

This story has been published from a wire agency feed without modifications to the text.