How do the fins of fish evolve into the wrist bones in mammals? Neil Shubin has traveled to some of the most barren and isolated parts of the planet to crack that mystery.
In the far reaches of the frozen Arctic Shubin searched for a fossil intermediate between fish and tetrapods, which include all land-living vertebrates, such as frogs, turtles, hawks, and lions. The group also includes a number of animals that have returned to life in the water, such as sea turtles, sea snakes, whales and seals.
Far in the Arctic, Shubin found Tiktaalik roseae, a 375-million-year-old fossil of a flat-headed fish with fin bones corresponding to limb and wrist bones.
Shubin and his lab then switched gears and used developmental genetics to investigate the evolution of limb development. Specifically, they looked at Hox genes, known to be important in mammalian limb development. Comparing Gar fish and mouse, they found similar patterns of Hox gene expression in fish fins and mouse forelimbs. This combination of fossil and genetic evidence suggests that the distal regions of fish fins evolved into wrist bones in mammals.
To make these extraordinary discoveries Shubin had to cross sweeping ice landscapes of the Arctic and Antarctic. He’s survived polar storms, traveled in temperatures that can freeze flesh in seconds, and worked hundreds of miles from the nearest humans, all to deepen our understanding of our world. It turns out that explorers and scientists have found these extreme environments as prime ground for making scientific breakthroughs across a vast range of knowledge. Shubin reveals just how far scientists will go to understand polar regions. In the end, what happens at the poles does not stay in the poles—the ends of the earth offer profound stories that will forever change our view of life and the entire planet.
Guest:
Neil Shubin is the Robert Bensley Distinguished Service Professor at the University of Chicago and associate dean for academic strategy of the university's Biological Sciences Division. He's also the author of Ends of The Earth: Journeys to the Polar Regions in Search of Life, the Cosmos and our Future. He is also the author of two other popular science books — The Universe Within: The Deep History of the Human Body (2013) and the best-selling Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body (2008). Your Inner Fish was named best book of the year by the National Academy of Sciences.
"The Source" is a live call-in program airing Mondays through Thursdays from 12-1 p.m. Leave a message before the program at (210) 615-8982. During the live show, call 833-877-8255, email thesource@tpr.org.
This interview will be recorded on Monday, February 10, 2025.
