Now, the reason they've done that is that they have evolved a body form that is very optimally designed for moving quickly through water. And so they have convergently evolved to be very similar. So the animals, if you saw one, you might - people mistake sharks for dolphins and the other way around. They're all streamlined animals with a powerful tail for propulsion, two flippers for steering and a dorsal fin for stability. They evolved from three very different ancestors, and yet they ended up looking almost identical. They all developed dorsal fins, flippers, sleek bodies, but they didn't all develop from the same set of accidents that were happening randomly. SIEGEL: And the best example that you give that I can recall is the remains of an aquatic dinosaur, a dolphin and a shark. LOSOS: Well, convergent evolution is when two species independently evolve to be similar.
SIEGEL: At the heart of your book and your conversion, I guess, is the growth in recent decades of an understanding of convergence as a principle in evolution. JONATHAN LOSOS: Thank you very much a pleasure to be here. He's a professor at Harvard and the author of a new book called "Improbable Destinies." One thing he is not anymore is quite so much a believer in Gould's insistence on chance and contingency driving evolutionary change. Losos read the book, and Gould helped inspire him to become a biologist.
Had one evolutionary step gone a different way, life on Earth could've ended up radically different. Biologist Jonathan Losos and I have at least one thing in common - we were both blown away by the late paleontologist Stephen Jay Gould's 1989 book "Wonderful Life." Gould saw evolution as being all about odd contingencies, accidents.
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