The ability to speak has allowed our species to pass knowledge between generations, articulate complex ideas, and build societies. Jarvis uses song-learning birds and other species as models to study the molecular and genetic mechanisms that underlie vocal learning, including how humans learn spoken language. He is interested in how their brains, and ours, have evolved to produce this complex behavior.
Unlike songbirds, the vast majority of animals—including common model organisms like mice and fruit flies—cannot imitate novel sounds and have limited vocal flexibility, reducing their usefulness in the study of spoken language. To advance research in this field, the Jarvis lab has developed a suite of experimental tools for songbirds designed to probe the underlying genetics of vocal learning. By using an integrative approach combining behavioral, anatomical, electrophysiological, and molecular biological techniques, Jarvis hopes to advance knowledge of the neural mechanisms of vocal learning, and more broadly, gain a deeper understanding of how the brain generates, perceives, and learns complex behaviors.
Beyond his work with songbirds, Jarvis is interested in using genomics to develop a comprehensive understanding of how vocal-learning and vocal non-learning species are related, providing insight into how vocal learning and other complex behaviors have evolved. As the co-leader of a consortium of over 200 scientists, from 101 institutions in 20 countries, Jarvis helped oversee the sequencing of genomes of species representing nearly all avian orders. These findings led to an overhaul of the bird family tree, and suggest that vocal learning evolved at least twice among birds: once in hummingbirds and once in a common ancestor of songbirds and parrots. Jarvis’s aspiration is to sequence the genomes of each bird species, a total of 10,500, and eventually the genomes of all 66,000 vertebrates, in order to understand how species are genetically related and how their unique characteristics evolved.
Working with results from the avian genomics project, Jarvis and his colleagues have discovered that hundreds of genes have similarly evolved in both the song-learning circuits of songbirds and the speech circuits of humans, and that many of the changes to these genes are not found in the brains of their close living bird and primate relatives. Some of these genes, when mutated, are associated with speech disorders in humans, and are predicted by Jarvis’s studies to control the development of speech brain circuits. These findings have significant implications, suggesting that an entire body of work in songbirds has direct relevance to humans.
Most recently the Jarvis lab has begun to study the molecules that guide neuronal connections, called axon guidance molecules. Jarvis hypothesizes that these molecules make the difference between a vocal learner and non-learner by directing the formation of a crucial neural circuit. This motor circuit, which has been linked to vocal organs, is believed to make fine motor control in the larynx possible, allowing the production of imitated speech. The Jarvis lab and others predict that the presence or absence of this neural circuit is one of the key transformations in the brain that enables vocal learning, and that axon guidance molecules are responsible for its creation. One of the Jarvis lab’s long-term goals is to use these molecules to induce a vocal-learning circuit in a species that can’t normally imitate speech, such as a mouse.