“In this work, the distinguished psychologist Herbert S. Terrace illustrates a unique comparative perspective on the nature and evolution of language.”
~ Charles Yang, author of The Infinite Gift: How Children Learn and Unlearn the Languages of the World
To continue his series on language in humans and animals, author of Why Chimpanzees Can’t Learn Language and Only Humans Can, Herbert S. Terrace discusses different forms of animal communication and why that does not constitute language. A bird’s song and a monkey’s animated gestures may seem to be a form of language, but Terrace explains the shortcomings.
Originally published in PsychologyToday.com.
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There are many forms of animal communication. In the lyrics of Let’s Do It, Cole Porter celebrated the diversity of signals that birds, bees, oysters, clams, sponges, and electric eels produce to attract mates. Those signals can be visual, auditory, tactile, chemical or electrical. If Porter were to add another verse to Let’s Do It, he might also include silk worms, ants and other species who signal their interest in mating with pheromones.
But it’s not just about mating that animals signal. They also communicate about the appearance of a predator, dominance, territoriality, fear, aggression and the discovery of food. Because of the variety and richness of animal signals, some psychologists regard them as a form of language.
In some instances, animals actually seem to name objects. For example, Cheney and Seyfarth showed that vervet monkeys emit one sound when they see an eagle, another when they see a leopard and a third when they see a snake.
Even bees can vary their signals. Karl von Frisch, a Noble laureate, showed that bees communicate the distance and the direction they flew to find food. When food is close to the hive, a foraging bee performs a circle dance, the diameter of which is proportional to the distance between food and the hive. If food is far away, the foraging bee performs a dance composed of two intersecting circles. Where the circles touch, they produce a straight line. The angle of that line with the sun defines the direction that other bees would have to fly to find food.
“As diverse and rich as these and other animal signal are, they are not language. The main reason is the signals are emotional. Their only function is to manipulate another animal’s behavior, not to share and exchange information.”
As diverse and rich as these and other animal signal are, they are not language. The main reason is the signals are emotional. Their only function is to manipulate another animal’s behavior, not to share and exchange information. Without those functions, animal signals don’t qualify as language.
As compared to words, animal signals are innate, immutable and involuntary. A vervet monkey can’t arbitrarily substitute a new sound for the sound it makes when it sees an eagle or the sounds it makes when it encounters other predators. Similarly, bees can’t arbitrarily change the dances they perform to signal the availability of food and which way to fly to find it.
By contrast, words are conversational and arbitrary. Upon seeing a flower, an infant learns to say flower to share her perception of that flower with a parent. She will often point to the flower and smile after naming it. She expects a reply like, what a pretty flower, that’s a red one, or a smile from her parent that says good job.
Animal signals, which are typically uni-directional, are never part of a conversation. A vervet monkey who sounds an alarm for a leopard doesn’t expect another monkey to say, thanks, I’ve already seen it, glad you told me, and so on. In those rare instances in which one animal answers another animal’s signal, as for example in bird duets, the answer is innate and immutable. It never adds new information.
“Animal signals, which are typically uni-directional, are never part of a conversation. A vervet monkey who sounds an alarm for a leopard doesn’t expect another monkey to say, thanks, I’ve already seen it, glad you told me, and so on.”
Because words are arbitrary, they can be translated into any language. The infant who learned to say flower in English could just as well have said fleur, in French, blume, in German, flor in Spanish, fiore, in Italian, цветок in Russian, and so on for the more than 6000 languages spoken throughout the world.
As I will elaborate in a future blog about ape language projects, a chimpanzee can be trained to make a gesture in response to a particular object, say a flower, but it will only do so to obtain a reward. Such uni-directional “imperatives” form a minuscule part of language. An infant would never acquire language if she could only learn imperatives.
On the other hand, there is no limit to the number of words a person can learn. It has been estimated that college students no more than 40,000 words. So long as there are new objects or actions to name, people can increase their vocabulary, for example, with the names of new elements, stars, diseases, countries, and so on. Because animal communication is entirely emotional, the number of signals an animal can make is limited, rarely more than a dozen in a particular species.
“It has been estimated that college students no more than 40,000 words. So long as there are new objects or actions to name, people can increase their vocabulary, for example, with the names of new elements, stars, diseases, countries, and so on.”
We have seen that animal communication consists of a variety of signals that are both rigid and inflexible. The gap between animal communication and language, which is arbitrary and infinitely flexible, makes it seem impossible for language to have evolved from animal communication.
Unfortunately, many linguists agree with Noam Chomsky that it’s “…safe to attribute the development [of language] to “natural selection”, so long as we realize that there is no substance to this assertion…it amounts to nothing more than a belief that there is a naturalistic explanation for these phenomena”.
Chomsky wasn’t the first person to question the evolution of language by natural selection. Ironically, Alfred Wallace, a co-founder of the theory of evolution changed his mind about language and natural selection twenty years after the publication of The Origin of Species. Wallace asked how man’s “superior intelligence” could result from natural selection, a process that would expand a creature’s powers only to the point at which it increased survival value. Specifically, Wallace wondered why humans have “a large and well-developed brain quite disproportionate to his actual requirement.”
“Admittedly, it’s difficult enough to explain how natural selection could explain the origin of words, but that problem is easier than the origin of grammar, a problem that has preoccupied Chomsky for most of his career.”
Why Chomsky, Wallace, and others were unable to see how natural selection could account for language is probably best explained by their failure to recognize that words and grammar evolved separately; words before grammar. Admittedly, it’s difficult enough to explain how natural selection could explain the origin of words, but that problem is easier than the origin of grammar, a problem that has preoccupied Chomsky for most of his career. Recent attempts to explain the origin of words, in Homo sapiens and in a recent ancestor, Homo erectus, supports the case that words evolved before grammar. I will describe those attempts in future blogs.
References: Cheney, D. L., & Seyfarth, R. M. (1992). How monkeys see the world: Inside the mind of another species. University of Chicago Press.
Chomsky, N. (1972). Language and Mind. New York: Harcourt Brace Jovanovich.
von Frisch, K. (1967). The dance language and orientations of bees. Cambridge, MA: Belknap Press, Harvard University Press.
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