“When, during the course of an interview for The New Yorker, I told the interviewer (Mark Singer) that I believed stories are found things, like fossils in the ground, he said that he didn’t believe me. I replied that that was fine, as long as he believed that I believe it. And I do. Stories aren’t souvenir tee-shirts or Game Boys. Stories are relics, part of an undiscovered pre-existing world. The writer’s job is to use the tools in his or her toolbox to get as much of each one out of the ground intact as possible. Sometimes the fossil you uncover is small; a seashell. Sometimes it’s enormous, a Tyrannosaurus Rex with all the gigantic ribs and grinning teeth. Either way, short story or thousand page whopper of a novel, the techniques of excavation remain basically the same.” (Stephen King’s manual On Writing)

The writer as a paleontologist leads me automatically to the fish paleontologist Neil Shubin and his famous book ‚Your Inner Fish‘ in which he says that every reptile, bird and mammal alive today is descended from ancient fish.

Sure enough, in 2004, scientists found one of those transitional species: Tiktaalik roseae, a 375-million-year-old Devonian period specimen discovered in the Canadian Arctic by paleontologist Neil Shubin and his colleagues. Tiktaalik, explains Shubin on the latest episode of the Inquiring Minds podcast, is an „anatomical mix between fish and a land-living animal.“

„It has a neck,“ says Shubin, a professor at the University of Chicago. „No fish has a neck. And you know what? When you look inside the fin, and you take off those fin rays, you find an upper arm bone, a forearm, and a wrist.“ Tiktaalik, Shubin has observed, was a fish capable of doing a push-up. It had both lungs and gills. In sum, it’s quite the transitional form.

 Shubin’s best-selling book about his discovery, Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body, uses the example of Tiktaalik and other evolutionary evidence to trace how our own bodies share similar structures not only with close relatives like chimpanzees or orangutans, but indeed, with far more distant relatives like fish. Think of it as an extensive unpacking of a famous line by Charles Darwin from his book The Descent of Man: „Man still bears in his bodily frame the indelible stamp of his lowly origin.“

And now, PBS has adapted Your Inner Fish as a three-part series (you can watch the first installment here), using the irrepressible Shubin as a narrator who romps from Pennsylvania roadsides to the melting Arctic in search of fossils that elucidate the natural history of our own anatomy.

„Many of the muscles and nerves and bones I’m using to talk to you with right now, and many of the muscles and nerves and bones you’re using to hear me with right now, correspond to gill structures in fish,“ explained Shubin on Inquiring Minds. Indeed, despite having diverged from fish several hundred million of years ago, we still share more than half of our DNA with them.

„The genetic toolkit that builds their fins is very similar to the genetic toolkit that builds our limbs,“ Shubin says. „And much of the evolution, we think, from fins to limbs, didn’t involve a whole lot of new genes.“