Nautilus: Neil Shubin has been going backward his whole life. “I teach anatomy but I want to understand why things look the way they do,” says the paleontologist and professor of organismal biology and anatomy at the University of Chicago. “And to understand the fundamental questions you have to go ever deeper into history. So I have gone backward from humans to fish to planets.”

Shubin, 53, is referring to his two books, Your Inner Fish and The Universe Within, which detail the atoms and molecules, genes and cells, sculpted by evolution into the common bonds of life. In 2004, on Ellesmere Island in the Arctic, Shubin discovered one of the key links in animal evolution, the fish known as Tiktaalik, that, he writes, “was specialized for a rather extraordinary function: it was capable of doing push-ups.”

Shubin and his team learned from Tiktaalik fossils that the big fish with the flat head had a shoulder, elbow, and wrist composed of the same bones in a human’s upper arm, forearm, and wrist. Tiktaalik used those bones to navigate shallow streams and ponds “and even to flop around on the mudflats along the banks.” Here was the creature from the lagoon that revealed how animals evolved from fish to us. [Continue reading…]