Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body

Our example will show us one of the great transitions in the history of life: the invasion of land by fish. For billions of years, all life lived only in water. Then, as of about 365 million years ago, creatures also inhabited land. Life in these two environments is radically different. Breathing in water requires very different organs than breathing in air. The same is true for excretion, feeding, and moving about. A whole new kind of body had to arise. At first glance, the divide between the two environments appears almost unbridgeable. But everything changes when we look at the evidence; what looks impossible actually happened. (View Highlight)

So, like a building made of bricks or concrete, bones are shaped so as to maximize their compressive functions and minimize twisting and bending, something Galileo recognized in the seventeenth century. (View Highlight)