What Birds Have to Say: Unlocking the Secrets of Human Language

Every day, beautiful chirps of millions of different bird species can be heard all around the world. However, this beautiful singing is far more than a background melody to your outdoor walk: it may be the key to understanding one of humanity’s biggest mysteries.

Through studying birdsong, researchers hope to gain a deeper understanding of how human speech has evolved and the mechanisms behind it. Vocal learning is a unique trait found in a few species of birds, cetaceans (marine mammals), bats, elephants, and some primates. The rarity of this trait makes song acquisition a field of interest to scientists from both an evolutionary and a neuroscience perspective, according to Dr. Wan-chun Liu, an associate professor of neuroscience and an ornithology researcher at Colgate University. Scientists hypothesize that vocal pathways may have evolved out of pre-existing motor pathways, long before birds and mammals split from a common ancestor. Over time, motor brain circuits evolved to connect with vocal control neurons. This theory may also apply to human speech pathways, which are located near motor areas in the brain.

Liu and many other researchers have primarily used songbirds as models because studying other animals that exhibit these traits, like whales, is not practical due to their size and habitat requirements. In terms of vocal organization and learning mechanisms, birds and humans exhibit many similarities. Hence, convenience isn’t the only reason behind an entire field of study concerning birdsong. Although whales and birds both produce complex learned songs, songbirds are more similar to humans in how vocalizations are learned and represented in the brain. The developmental stages of learning song or speech are remarkably similar in humans and birds. Like a baby’s first goo-goo-gah-gah, “birds also start with this babbling subsong, and then they gradually modify it to achieve vocal imitation of their tutors,” Liu explains. Another similarity lies in the social aspects of birdsong, which parallels human speech. Birds rely on song — just as humans rely on speech — to make friends, find partners, and communicate territory.

Of course, not everything about bird and human voices is the same. There are some key structural differences to produce sound, most notably between the avian vocal organ (syrinx) and human vocal organ (larynx). The syrinx is a two-sided vocal organ capable of producing sounds from each side of a bird’s throat. On the other hand, the larynx is a unilateral structure. Both still share the same major functions, regulating airflow from and to the lungs and modulating airflow during sound production.

An additional difference is that for birds, the left vocal muscles are controlled by the left side of the brain and the right vocal muscles are controlled by the right side of the brain. In contrast, for humans, the control usually comes from the opposite side. Yet, despite these structural differences, birds have proven to be valuable species to study because they use the same types of brain circuits to learn and produce song that humans use for speech. In both, the brain pathways that control vocalization are organized in a hierarchy, meaning they have layers, from basic to more complex.

The study of birdsong also has powerful medical implications, especially for understanding links between the brain and behavior, offering insights into both normal function and neurological disease.

“Both speech and song pass through the basal ganglia, a [brain] region also implicated in neurodegenerative disorders like Huntington’s, Parkinson’s, and Alzheimer’s,” says Liu. For instance, researchers have lowered dopamine levels in zebra finches, mimicking a key feature of Parkinson disease, to observe how dopamine shortages disrupt specific brain regions involved in vocal control.

Using songbirds as models, researchers can discover and understand the importance of certain genes, too. For example, both birds and humans have the FOXP2 gene, which is critical for vocalization. Mutations in the gene are linked to severe speech disorders in humans and difficulty in learning songs in birds.

While Liu acknowledges that the field has made remarkable strides in recent decades, he emphasizes that much remains unknown about the exact neural circuitry and mechanisms underlying birdsong. “In the future, perhaps we can manipulate genes in the brain to learn more about the functions of birdsong,” he says.

Birdsong research is not just for birds — it’s about humans too. Whether viewed through evolutionary, neurological, medical, or behavioral lenses, birdsong continues to offer rich opportunities for discovery.