Numbers in the News: Can I Really Have a Set of Artificial Gills?

According to a story in CNN, you may soon be able to slip into a set of artificial gills, and take to the water without having to haul along a pressurized tank of the atmosphere.Sure. Why not? After all, fish do it all the time. Oddly enough, it never occurred to the evolutionary algorithms that brought us whales and dolphins to re-evolve time-tested gills, even though mammals managed to reacquire flippers in lieu of fins, and modify their bodies in gobs of other ways, in order to live in the wa...