Earth is home to more than 7,000 languages, and we use those languages to express ideas as straightforward as the desire for a cup of coffee and as intricate as the details of quantum physics. But how did language start and when did humans first evolve this ability to use language?
The development of human language has long fascinated scholars and linguists. These experts have various perspectives and theories for when humans started speaking and the reasons language evolved in the way that it did. There is much to learn from the laryngeal descent theory, to the arguments made for neurological and intelligence-based speech development.
The laryngeal descent theory (LDT) posits that language became possible only after anatomically modern Homo sapiens evolved around 200,000 years to 300,000 years ago. In H. sapiens, the larynx is lower in the throat than in our pre-H. sapiens ancestors or in modern non-human primates.
This position of the larynx makes the vocal tract longer, making it possible to produce a variety of speech sounds, particularly the subtle distinctions among vowel sounds that our ancestors could not and other primates cannot make. Scientists call this the LDT and for many years, it was the most widely accepted view.
However, in 2019, a study in Science Advances called that dogma into question. The researchers looked at decades of research on primate vocalizations and anatomy, for example, research that found that the macaque, an Old-World monkey, has the necessary anatomy to support spoken language and is quite capable of distinctly producing the vowel sounds, “bit,” “bet,” “bat,” “but,” and “bought.”
Based on this research and other data, the authors argue that the ability to make speech sounds goes back to the time when humans and Old-World monkeys last shared a common ancestor, as long as 27 million years ago.
As might be expected with such a dramatic shift in dogma, not everyone agrees with that timeline. In an article for The Conversation, George Poulos, a linguist at the University of South Africa, says that the first speech sounds came along a mere 70,000 years ago, and the ability to produce vowel and consonant sounds didn’t evolve until around 50,000 years ago.
The first signs of human language were clicks followed by more elaborate language as the tongue, mouth, pharynx, nasal passages, and larynx gradually evolved.
Another theory is that neurological changes may have been the driver of the ability to produce speech. That’s the conclusion of the authors of the 2019 paper. The reason Old-World monkeys can’t talk, the researchers say, is not because of the anatomy of their vocal tracts but because they don’t have the necessary neural structures. The neurological language theory seems to be holding up better than LDT.
Richard Futrell, assistant professor at the University of California Irvine, who studies language processing in humans and machines, explains why a certain level of neurological development is necessary for spoken language. “Speaking requires fine-grained motor control, and it has to be fast,” he says.
That high-speed control was provided by more direct connections between the motor cortex and the vocal tract. Futrell says that neurons are like telephone poles sending signals from your brain to other parts of your body.
If the signal has to make too many hops before it can control your mouth, it will be too slow for much precision. “There seems to be a special fast path for control of the vocal apparatus in humans that enables humans to produce more different sounds reliably,” Futrell says.
Another possible explanation is that language is simply a consequence of increasing general intelligence. The more information processing capacity you have, the more complex patterns you can understand and produce.
Futrell describes a line of research that correlates intelligence and language based on computer simulations. The basic finding, he says, is that if you simulate agents communicating with each other using signals, they have to coordinate with each other to come up with a set of signals that enable them to communicate well. This naturally produces a kind of linguistic structure, but the languages have to be simple so that they’re easy to learn.
It may come as a surprise if you’ve ever tried to master Spanish imperfect tenses or figure out why German verbs keep leaping to the ends of sentences, but language systems are actually pretty simple. Futrell explains: “Imagine if you had to memorize 20 million different words, each of which expresses a very precise meaning. That would be really hard. Instead, we have languages with 10,000 to 50,000 words and a simple set of rules that allows us to combine words to form sentences.”
As we got smarter and found more things we wanted to communicate, we ran into what Futrell calls a “simplicity bottleneck.” We couldn’t just keep adding more words. We didn’t need a lot of linguistic structure when all we needed to communicate was a few distinct calls to warn of predators or to attract a mate or threaten a rival,
“Our brains aren’t big enough; our lives aren’t long enough to learn them all,” he says.
At that point, if the computer models are correct, linguistic structure was inevitable. This may also, Futrell says, have led to a runaway evolutionary dynamic where an increase in the complexity of culture meant that people who had better communication had more evolutionary success; meanwhile, better communication led to even greater cultural complexity. Before you know it, you have 7,000 languages and mind-twisting conversations about quantum physics.
Read More: How Learning a Language Changes Your Brain