The Neuroscience of Speech, Language, Music, and Movement with Dr. Erich Jarvis

This episode features Dr. Erich Jarvis, a pioneering neurobiologist, who challenges conventional distinctions between speech and language, proposing that they are not separate brain modules but rather integrated functions of specialized production and perception pathways. He argues that the speech production pathway, unique to humans, parrots, and songbirds, contains all the complex algorithms for spoken language, while the auditory perception pathway is more widespread across the animal kingdom. Dr. Jarvis highlights the profound evolutionary link between speech production and gesturing, suggesting that the brain pathways controlling speech likely evolved from those governing body movement, with adjacent brain regions supporting both functions.

Dr. Jarvis delves into the fascinating world of vocal learning, distinguishing between innate vocalizations (like crying or barking) and learned vocal communication, which is a rare and specialized ability found in humans and only a few bird species like songbirds, parrots, and hummingbirds. He explains how, in these vocal learners, forebrain circuits have taken over the brainstem to enable complex learned vocal behaviors. The discussion reveals remarkable parallels between human language acquisition and birdsong learning, including critical periods for learning, the deterioration of vocalizations upon deafness, and the involvement of homologous brain circuits and even similar underlying genes, such as FOXP2, which can cause speech deficits in both humans and vocal learning birds.

The conversation also touches on the deep connection between language, music, and movement. Dr. Jarvis shares intriguing examples, such as the sub-perceptual motor activity in the throat during reading, indicating a continuous link between internal thought and motor speech. He also describes hummingbirds' astonishing ability to coordinate wing movements with their songs, sometimes creating percussive sounds that are integral to their vocalizations. These examples underscore the integrated nature of these complex behaviors and their shared neural and genetic underpinnings.

Broader implications of Dr. Jarvis's work extend to understanding speech disorders like stuttering, facilitating multiple language learning, and appreciating the evolutionary timeline of human language, which he suggests may have emerged between 500,000 to a million years ago, potentially even present in Neanderthals. His research emphasizes that complex behaviors like language are not isolated but are deeply intertwined with motor control, social bonding, and genetic predispositions, offering a holistic view of how we communicate and interact with the world.

"I start to see there really isn't such a sharp distinction."

"Instead, there is a speech production pathway that's controlling our larynx, controlling our jaw muscles that has built within it all the complex algorithms for spoken language."

"And the brain regions I mentioned are directly adjacent to each other. And why is that? I think that the brain pathways that control speech evolved out of the brain pathways that control body movement."

"When people think of what's special about language, it's the learned vocalizations. That is what's rare."

"But in humans and in parrots and in some other species, somehow, we acquired circuits where the forebrain has taken over the brain stem and now using that brain stem, not only to produce the innate behaviors or vocal behaviors, but the learned ones as well."

"So I think Neanderthals had spoken language. I'm not going to say it's as advanced as what it is in humans. I don't know. But I think it's been there for at least between 500,000 to a million years that our ancestors had this ability."

"And now we're finding the specific mutations are also similar, not always identical, but similar, which indicates remarkable convergence for a so-called complex behavior in species separated by 300 million years from a common ancestor."

"Hummingbirds hum with their wings and sing with their syrinx."

"It has something to do with also the social bonding with your own species."

"And the lowest common denominator is going to be what they share. And so the phonemes that"