What kind of sound does a dog make? That depends on which language you speak. Dogs are said to go ouah ouah in French, but ruff or woof in English.
Crucially, however, the sounds that the dogs themselves make do not vary in this way. Dogs growl, whine, bark, howl and pant in the same way all over the world. This is because such sounds are part of the innate behavioral repertoire that every dog is born with. This basic vocal repertoire will be present even in a deaf and blind dog. This is not, of course, to say that dog sounds do not vary: they do. You may be able to recognize the bark of your own dog, as an individual, and different dog breed produce recognizably different vocalizations. But such differences are not learned; they are the inevitable byproducts of the fact that individuals vary, and differences at the morphological, neural or “personality” level will have an influence on the sounds an individual makes. Dogs do not learn how to bark or growl, cats do not learn how to meow, and cows do not learn their individual “moos”. Such calls constitute an innate call system. By “innate” in this context, I simply mean “reliably developing without acoustic input from others” or canalized. For example, in experiments where young squirrel monkeys were raised by muted mothers, and never heard conspecific vocalizations, they nevertheless produced the full range of calls.
The same regularity applies to important aspects of human communication. A smile is a smile all over the world, and a frown or grimace of disgust indicates displeasure everywhere. Not only are many facial expressions equivalent in all humans, but their interpretation is as well. Many vocal expressions are equally universal. Such vocalizations as laughter, sobbing, screaming, and groans of pain or pleasure are just as innately determined as the facial expressions that normally accompany them. Babies born both deaf and blind, unable to perceive either facial or vocal signals in their environment, nonetheless smile, laugh , frown, and cry normally. Again, just as for dog barking, individuals vary, and you may well recognize the laugh of a particular friend echoing above the noise in a crowded room. And we have some volitional control over our laughter: we can (usually) inhibit socially inappropriate laughter. These vocalizations form an innate human call system. Just like other animals, we have a species-specific, innate set of vocalizations, biologically associated with particular emotional and referential states. In contrast, we must learn the words or signs of language.
This difference between human innate calls, like laughter and crying, and learned vocalizations, like speech and song, is fundamental (even down to the level of neural circuitry). An anencephalic human baby (entirely lacking a forebrain) still produces normal crying behavior but will never learn to speak or sing. In aphasia, speech is often lost while laughter and crying remain normal. Innate human calls provide an intuitive framework for understanding a core distinction between language and most animal signals, which are more like the laughs and cries of our own species than like speech. Laughs and cries are unlearned signals with meanings tied to important biological functions. To accept this fact is not to deny their communicative power. Innate calls can be very expressive and rich – indeed their affective power may be directly correlated with their unlearned nature. The “meaning” of a laugh can range from good-natural conviviality to scornful, derisive exclusion, just as a cat’s meow might “mean” she wants to go out, she wants food, or she wants to be petted. Insightful observers of animals and man have recognized these fundamental facts for many years.
Obviously, signals of emotion and signals of linguistic meaning are not always neatly separable. In vocal prosodic cues, facial expressions, and gestures, our linguistic utterances are typically accompanied by “non-verbal” cues to how we feel about what we are saying. One signal typically carries both semantic information intelligible only to those who know the language, and a more basic set of information that can be understood by any human being or even other animals. Non-verbal expressive cues are invaluable to the child learning language, helping to coordinate joint attention and disambiguate the message and context. They also make spoken utterances more expressive than a written transcription alone. Other than the exclamation mark or emoticons, our tools to transcribe the expressive component are limited, but the ease and eagerness with which humans read illustrates that we can nonetheless understand language without this expressive component. This too, reinforces the value of a distinction between two parallel, complementary systems.
As we discuss other animals’ communication systems, I invite the reader to compare these systems not only to language exchanges, but also to the last time you had a good laugh with a group of friends, and the warm feeling that goes along with it, or the sympathetic emotions summoned by seeing someone else cry, scream, or groan in pain. The question we must ask – “is this call type more like human laughter and crying, or more like speech or song?”. I will shortly argue that all non-human communication systems fall in the former category.