“To breathe air with a lung … you need neural circuitry that is sensitive to carbon dioxide,” Michael Harris, UAF neuroscientist, said. 

That neural circuitry is called a rhythm generator, and it is what allows air-breathing organisms to take in oxygen and expel carbon dioxide as waste.

So scientists went looking for a rhythm generator in non-air breathing vertebrates. They found one in the lamprey, an ancient fish with characteristics similar to the first vertebrates.

As larvae, Lampreys live in tubes dug in soft mud and breathe by pumping water through their bodies. When its tube gets clogged, a lamprey clears it with a cough-like mechanism. A rhythm generator is what controls the cough.

“We thought the lamprey ‘cough’ closely resembled air breathing in amphibians,” said Harris.