“From the pages of Your Inner Fish, it is clear that if a supreme being were responsible for creating life on Earth, from bacteria to humans, He or She displayed little intelligence. Far from being the perfectly crafted handiwork of a deity, our bodies are jerry-rigged patchworks of old bones, cells and genes bolted on to old frameworks that creak and groan at every opportunity. Men suffer hernias because their spermatic cords, inherited from ancient fish ancestors, leave them susceptible to gut tissue spilling through muscle walls, for example, while the evolution of the voice box has left us vulnerable to all sorts of breathing and swallowing ailments.
“Or consider hiccups. Spasms in our diaphragms, hiccups are triggered by electric signals generated in the brain stem. Amphibian brain stems emit similar signals, which control the regular motion of their gills. Our brain stems, inherited from amphibian ancestors, still spurt out odd signals producing hiccups that are, according to Shubin, essentially the same phenomenon as gill breathing.”