Actor David Tennant has an extra toe. Two anatomists explain what’s so fascinating about polydactyly

A common anatomical variation is being born with more than ten fingers or more than ten toes.

Former Doctor Who actor David Tennant this week confirmed he has 11 toes. He says he was born with an extra toe on his right foot, meaning he has polydactyly.

Here’s how this anatomical variation occurs, and how common it really is.