How to build a better lung

During the most recent meeting of Geology 601 (Crises in Earth History), we discussed how oxygen has influenced the evolution of different species. I was surprised to learn that bird lungs operate quite differently from ours. Instead of inhaling and then reversing flow when exhaling (“tidal” breathing), birds have a clever lung design that permits them to circulate air in a single direction continuously. The page reached by clicking on the image at right explains it nicely (I love the diagram). One key advantage of this lung design is the much higher oxygen utilization you get, which is handy if you’re a bird and may need to operate at higher elevations. Presumably we’re stuck with our low-efficiency in-out lungs because we lacked evolutionary pressure to improve upon them. :)