Who hasn’t long to talk to the animals like Dr. Dolittle. There’s no doubt that all animals have ways of communicating with each other, whether it’s a barking dog, a color-changing squid, or even a signing gorilla. But these animal calls are far from the in-depth conversation we’re used to having over a cup of tea. That’s because almost all animals like the ability to talk using subtle changes in their vocalizations to convey complex meanings about themselves, their actions, and their innermost thoughts.
Animal researchers have tried to teach nonhuman primates to talk. They even raised baby chimpanzees in human homes to expose them to speaking like human babies. But all these attempts have failed. Because of some influential studies a couple of decades ago, most scientists thought that nonhuman primates’ vocal anatomy was to blame. But, according to a paper published in Science Advances this month, their brains might be the limiting factor.
The reasons why animals can not talk
In the 1960s and 1970s, scientists studying rhesus macaques and chimpanzees used computer programs to figure out the range of sounds they should be able to make. They concluded that these primates’ throats and mouths couldn’t produce all the sounds needed for a language like ours. It supported the idea that modern humans evolved some special vocal anatomy that paved the way for language rather than developing special brain mechanisms to coordinate advanced vocal tracts.
But these critical 1969 computer models were based on plaster casts of the vocal tracts of dead rhesus macaques. Those scientists tried to shape the monkeys’ tongues and lips to approximate what a bark would look like. Then estimated the whole range of movement. It may or may not have captured the full flexibility of a live monkey.
Vocal evolution
Our linguistic skills depend partly on the intricate machinery in our chests, throats, and mouths. The muscles contracting of the ribcage and the diaphragm compresses the chest cavity. They force puffs of air out of the lungs and up throughout the trachea. The rushing air passes through the voice box’s larynx, where it vibrates thin stretched membranes or vocal cords to produce a sound.
Using the muscles in the throat, we can change how tightly the vocal cord membranes are pulled, which changes the pitch of the sound. But that’s not talking yet because the sound then passes through mouths where it needs to run the gauntlet of tongue and lips. Then, try talking while keeping your jaw, tongue, and lips still.
So while the larynx is responsible for turning a puff of air in the lungs into a sound in the throat, the flexible part of the mouth shapes the words we say. But why’d animals fallen short? Even gorillas and chimpanzees are our closest evolutionary relatives and don’t have anything like the complex language we humans do. Scientists think that it’s down to the shape of their mouths and throats. Our impish cousins have short sloping necks and large protruding jaws, giving them big mouths, which could be eating but are less good for making words.
On the other hand, humans have longer necks and smaller mouths, which gives more versatility in the noises we can make. It doesn’t take much movement of jaws, tongue, and lips to form a whole range of words. So Homo sapiens is uniquely gifted with the right-shaped throat to make the noises that call words. But we could learn something from the humble bird regarding vocal acrobatics.
Vocal learners
Birds have what’s known as a syrinx in place of the larynx. They can produce some of the most beautiful and complex songs with it. Searing Cesare even versatile enough that some birds like parrots. Lyrebirds can form human words and imitate the sounds of machinery and vehicles. What sets these extraordinarily gifted birds apart is their vocal and learners? They can hear a sound learn how to make it, and then repeat it. It’s like us mimicking the wolf of a dog or the cow.
Humans are vocal learners, and so apparent, but not many other animals are. They’re only able to make the sounds. The secret lies not in the shape of the voice box but in its connections with the brain. Vocal learners have a direct link between their forebrain and vocal muscles. It gives them precise control and understanding of the sounds they can make. But while they might be able to understand how to make the sounds.
No other animal has yet shown that it understands what those sounds represent. With one exception African Grey parrot called Alex, who, during a day of learning to repeat color words, looked at himself in the mirror and asked what color am I. To ask an existential question like that, Alex must have cracked the fundamental skill of speaking and organizing words into meaningful, novel sentences.
Aside from Alex, only humans have ever been known to do this. It’s probably a direct result of how big complex brains are. Humans have specific brain areas dedicated to understanding, planning, and producing speech. They’re called Broca’s area and the Verne occurs area.
Monkeys and apes have similar structures involved in making and face gestures. But that’s where the similarities end. Monkeys’ noises come not from Broca’s area but from the more primitive limbic system and brain stem. It’s a particular quirk of neurology that means we can perform mental acrobatics to grapple with language.
Gene mutation
Have you ever wondered why humans are the only species capable of talking? If chimps are so smart, why can’t they speak? Scientists have discovered the reason behind humans’ unique ability to produce and understand speech, and it turns out.
It may have arisen from a gene mutation over half a million years ago. That gene is called FoxP2 and exists in humans and chimps. Its connection to language was first discovered in family members who had severe speaking and understanding speech difficulties. That family was found to be carrying a mutated version of the gene.
A study published in Nature about FoxP2 showed that the human and chimp versions of the gene look different and function differently. Somewhere around that time, humans began developing the capacity for speech. Our FoxP2 gene became mutated. That mutation resulted in different gene targets being switched on or off in human and chimp brains.
In that study, scientists genetically engineered mice to express the human form of FoxP2. Mice were given that mutation learned to run a maze much more quickly than normal mice. It means their learning capacity was effectively enhanced. Specifically, they developed the ability to turn mindful actions into behavioral routines. It is a necessary learning process for developing language.
- It hinges on two key types of memories: declarative memory, the memory of events and places, and procedural memory needed for routine tasks.
In humans, those two types of memories work in conjunction. So when somebody shows us a hand, for example, and says the word “hand,” – we’re transforming the experience of hearing that word into an automatic association. Human brains now associate the word hand with objects that look and function like hands. Once we learn that association, it’s with us forever.
That’s why, when we’re performing routine actions, like driving to work, we don’t need to think about it as we’re doing it consciously. But that’s not the case for other species. Our unique ability to do that is an essential part of how we’ve come to develop and understand speech.
It’s crazy to think that a single gene mutation could be responsible for our entire language development. It doesn’t completely rule out the possibility that other animals could someday develop speech. Of course, even if they did develop that mutation naturally, it would still take thousands.
Animal Vocal Experiment
A team of international researchers wanted to create an updated model. These researchers took X-ray videos of three living rhesus macaques while making many different facial expressions: noises, chewing and swallowing. They digitally traced the monkeys’ vocal tracts’ outlines and used those tracings rather than estimated movements.
To create a computer model of how they could contort their mouths and throats. Some fancy math let them calculate the range of sounds the monkeys could theoretically make, using an English-speaking adult human female for comparison.
The scientists concluded that the macaques should almost make most vowel sounds in American English. They even used their results to simulate what it would sound like if a macaque said, “Will you marry me?” mixed with some noise. It’s terrifying. But the creepiness is beside the point. Why did they choose that particular phrase?
But these researchers made this model fly in the face of decades of belief that nonhuman primates can’t talk. It’s because their throats can’t make the right sounds. Instead, their brains might be the limiting factor. After all, even though the physical pieces are mostly in place. Their neural circuitry doesn’t give them a fine level of control. They need to mimic human language.
So it seems that when we’re chattering away over a cup of tea, we’re making use of a startlingly complex combination of physical and mental apparatus. Other animals might have that talking toolkit, but we have the complete package alone.
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Sources:
Jordania, Joseph. Who Asked the First Question? The Origins of Human Choral Singing, Intelligence, Language and Speech. Tbilisi: Logos. ISBN 978-99940-31-81-8.
Kirby, Alex. “Parrot’s oratory stuns scientists.” BBC News.
F.X. Plooij. “Some basic traits of language in wild chimpanzees?”. In A. Lock (ed.). Action, Gesture, and Symbol. New York: Academic Press.
