The discovery suggests that all amphibians, reptiles, birds, and mammals currently have—or had in their past—the brain machinery necessary for vocalizing.
Sharks and their close relatives, for example, are thought to be silent, but they might still have the brain wiring that controls vocal noises.
What's more, Bass speculates, many more animals might vocalize for communication than we realize.
"How carefully have all animals been looked at for people to know that in fact they don't make sounds?" he said.
"If you don't study animals at the right time of year, you might not pick up that they're making any sounds."
The research is detailed in this week's issue of the journal Science.
"Beautiful Diversity"
Melina Hale, a biologist at the University of Chicago, expressed astonishment at the deep evolutionary history of the brain circuit for vocalizing, and she suspects many other scientists will be surprised as well.
"When we think about vocalization and our own ability to talk or birds' ability to sing, we think of it as very specialized for terrestrial vertebrates," Hale said. "But this isn't a key innovation of ours."
Hale added that even though the different vertebrate groups share the same brain mechanism, each lineage exploits it differently to produce sounds.
Toadfish vocalize using their swim bladders, birds use an organ called the syrinx, and mammals use their larynxes. (Related: "Fastest Known Muscles Found in Songbirds' Throats" [July 10, 2008].)
"There's this fundamental similarity in brain circuits," Hale said, "but then there's this beautiful diversity on top of it."
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