One-way airflow, thought to exist only in birds, may keep several reptiles going
chas53/iStockphoto (bird); GlobalP/iStockphoto (alligator)
Colleen Farmer was alone one night dissecting an alligator. Her focus was on blood flow in the heart, when suddenly, a hypothesis unfolded about animal lungs. In one sweep, she realized that what physiologists have assumed for decades about the evolution of airflow in alligators, other living reptiles, birds and maybe even dinosaurs might just be startlingly wrong.
Lungs sound simple: Air goes in, air goes out. But, like breathing itself, lungs are easy to take for granted and full of unexpected puzzles. In her windowless lab at the University of Utah, Farmer pondered two basic questions: Which direction does air really flow in lungs, and how did it evolve that way?
In people, air flows like the tides. Inhale, and air whooshes in. Exhale, and the air recedes along the same path, depleted of oxygen and laden with waste gas. Physiologists have believed that other vertebrates share this basic two-way