The Gentle Humming of Fish: Evolution of Vocalization
I had no idea that fish could hum, Disney movies notwithstanding. Not only do some fish hum, though, but their humming is controlled by a similar brain circuit to ours. These musical fish can teach us about our own ability to speak, and how that means of communication evolved.
The finding is based on a study of toadfish and their close relatives midshipman fish, which both use their air-filled swim bladders to grunt, growl, and hum to attract mates and defend territories.
Andrew Bass of Cornell University and colleagues mapped this neuronal network in larval toadfish and midshipman fish. The team found that the circuit for vocalizing develops across a specific brain region that includes the base of the hindbrain and the upper spinal cord.
This is precisely the same pattern of brain development seen in other vocalizing vertebrates, including birds, amphibians, and primates such as humans.
The last time all of these creatures shared a common ancestor was more than 400 million years ago, when the evolutionary line that led to toadfish split from the line that eventually led to land vertebrates.