Why we speak and chimpanzees don’t

Author: Beatriz Gómez-Vidal is a predoctoral researcher at the University of the Basque Country, Dep. Of Linguistics and Basque Studies (UPV/EHU) and member of The Bilingual Mind Research Group (Gogo Elebiduna)

Imagine this: you’re visiting the chimpanzee enclosure at a zoo. Some sit on the grass, chewing on leaves and scratching their heads, while others hang from the wooden beams. In a corner, a female is holding her baby. You can’t help but picture a human mom doing it in the exact same way. For a brief moment, you lock eyes with her, and you notice something special. Something eerily human. So much so that you could almost imagine her talking. But instead, all you hear is hooting, and grunting, and screaming. No words.

And so you wonder: how come we speak, and they don’t?

If you’ve ever asked yourself this question, you are not alone. In fact, scientists from a wide variety of fields have spent almost a century wondering about the same thing. We now know that we share about 96% of our genetic makeup with chimpanzees [1], making them our closest living relatives among the great apes. And underneath all that fur, we truly are very much alike. Like us, chimpanzees engage in social play, create life-long bonds, and have close friends; they also prefer cooked food, are conscious of their own thoughts, and even smile socially [2–7].

And yet, when it comes to communication, it seems that we couldn’t be more different. Chimps use hoots, barks and grunts to communicate about a limited number of topics (i.e., food, interactions and danger) [8,9]. But not humans: instead, we have developed the rarest communication system on Earth. To the unsuspecting language user, this may seem like an overstatement, but it so isn’t. In language, we combine meaningless phonemes (or cheremes in sign language) into meaningful words, and then combine those words into sentences to produce a complex, structured meaning. And it is all-purpose too: we can talk about the dead, make up stories, hypothesize about the future or retell the events that transpired on a Wednesday.

Powerful, isn’t it? Yes, and very annoying. Because if our closest living relatives don’t have it, then where does language come from? How did it evolve? In essence, how come we speak and they don’t?

Well, the short answer is that we still don’t know exactly. The long answer is that it’s complicated and that the index finger is kind of the protagonist. Allow me to elaborate…

The humble act of pointing

The first mind-blowing fact you should know about this linguistic puzzle is that chimpanzees are not as languageless as they may seem. As it turns out, chimps raised by humans in linguistically-rich environments do develop some remarkable linguistic abilities [10,11]. Due to differences in vocal tract anatomy between us and them, captive apes were often instructed in sign language, a modality which allowed them to become skilled in both comprehension and production. Washoe, a female chimp raised by humans, was known to understand and use linguistic signs consistently to refer to objects or other animals, both in the presence of people and by herself. She also invented at least one new sign on her own, and she could make up new “words” by putting already known signs together to refer to a new object. For instance, she once called a Brazilian nut a “rock berry”, which is kind of brilliant—and descriptive!

Evidently, these studies have been nothing short of controversial. They were plagued by methodological and ethical concerns, and the fact that there were great differences between individual apes begs the question of how representative they were of their species’ abilities as a whole. However, you have to give it to them: it’s a fascinating discovery either way. The fact that great apes can learn some linguistic abilities suggests that they must possess some of the cognitive requirements necessary for language development, like understanding referentiality, meanings and compositional structure. Interestingly, new evidence has just been uncovered that shows wild chimpanzees combine individual calls into larger structures; this resembles the way syntax operates in human language [9]. So what is actually missing? What’s the secret ingredient that we so mysteriously possess? Well, some researchers believe that it could be boiled down to one very simple, and yet uniquely human gesture: the humble act of pointing.

No point in pointing for a chimpanzee

When you extend your index finger and demand another human’s attention to an object, you may think that you’re doing something quite simple. After all, even preverbal babies can do it [12,13]! And yet, as straightforward as it seems to us, pointing does not come as easily for our furry cousins. In fact, no other great ape has been documented to engage in pointing with other apes, neither in captivity nor in the wild [14,15], and experiments show that pointing is one of the human gestures that they just do not understand [14,15]. This is because chimps are not aware of another’s intention to communicate in pointing [12]. They can keep track of the goals and intentions of others rather nicely, like understanding that an outstretched arm means an intention to grab the object in front of it [12,14,15]. But it seems that they just can’t wrap their heads around the fact that another individual is intentionally trying to grab their attention to focus on the same thing together, even if there is nothing to gain for the individual who is doing the pointing.

Weird, isn’t it?

As it turns out, not so much, since there are many similarities between pointing and human language [12]. In both cases, a human is trying to communicate with another on the basis that the sign can be understood because of their common knowledge. Both in language and in pointing, we’re aware of the other’s intention to communicate, and because of this we place our attention on whatever the producer is drawing attention to. And so we both end up thinking about the same thing. It’s as if humans routinely engage in something like mind-reading with other humans. If you think about it, this is what you have been doing this whole time. You see, I know that you know that I typed these sentences to share some ideas with you, and that’s why, as you read, you keep synching up your thoughts with mine by retrieving the words I gave you in order to form those ideas in your own head. This is the way in which you have been mind-reading me—admittedly, with some delay—during the process of understanding this article. And you couldn’t have done if our ancestors hadn’t invented pointing first, which is hypothesized to have laid the groundwork for language in our species [12].

So now you know why your index finger seems to be the secret ingredient in the human recipe for communication. Behind it, there lay the most amazing artifacts of human cognition: our instinct to communicate intentionally, and our ability for mind-reading, which may well explain the century-long mystery of why we speak and chimpanzees don’t. So, the next time you catch yourself pointing at something, give it some credit and remember that it is this simple gesture what likely preceded the emergence of language in our species. One could even go as far as saying that, without our instinct for pointing, humanity as we know it might have never existed.

References

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