The first time a fish crawled out of the water and onto land, it was a turning point that led to brand new kinds of life. But this couldn’t happen on its own: that fish would have needed both lungs and legs.

Neil Shubin, evolutionary biologist and author of Some Assembly Required (£18.99, Oneworld), says that fish didn’t evolve these traits to help them live on land. In fact, the reason they could live on land was that they repurposed the body parts they had already.

The same remarkable changes have happened all through evolutionary history, from the first vertebrate life to the first flying dinosaurs.

He speaks to our Online assistant Sara Rigby.

Let us know what you think of the episode with a review or a comment wherever you listen to your podcasts.

Listen to more episodes of the Science Focus Podcast:


Sara RigbyOnline staff writer, BBC Science Focus

Sara is the online staff writer at BBC Science Focus. She has an MPhys in mathematical physics and loves all things space, dinosaurs and dogs.