Washington, July 18 : A male midshipman - a close relative of the toadfish - doesn't require macho looks to attract females, for his humming is more than enough to do the trick. Now, a group of researchers has suggested that this sound is not only useful for the fish but also for science - as it can help in tracing the earliest developments of vocalization in other animals, including people.
In the study, which is published in Science, three Marine Biological Laboratory (MBL) visiting investigators show that the sophisticated neural circuitry that midshipman use to vocalize develops in a similar region of the central nervous system as the circuitry that allows a human to laugh or a frog to croak, evidence that the ability to make and respond to sound is an ancient part of the vertebrate success story.
The research is presented by Andrew Bass of Cornell University, Edwin Gilland of Howard University College of Medicine, and Robert Baker of New York University Medical Center.
"Fish have all the same parts of the brain that you do," says Bass, the paper's lead author.
The way our brains work is also similar. Just as we have neurons that coordinate when our larynx and tongue change shape to produce words, toadfish and midshipman orchestrate the movement of muscles attached to their swim bladder to produce grunts and hums.
Using larval toadfish and midshipman, the group traced the development of the connection from the animal's vocal muscles to a cluster of neurons located in a compartment between the back of its brain and the front of its spinal cord.
The same part of the brain in more complex vertebrates, such as humans, has a similar function, indicating that it was highly selected for during the course of evolution.
Scientists have known for decades that these fish make sounds, but they are not the only species whose hums, growls, and grunts have meaning.
"There's reason to suggest that the use of sound in social communication is widespread among fishes," Bass says.
This research is an example of the growing field of evolutionary neurobiology, which aims to understand the evolution of behavior through neurobiology.
According to Bass, fish are an incredibly successful group, making up nearly half of the living species of vertebrates, and vocal communication may be partly responsible.