You don't usually discover a new species of ancient human from a child's pinky bone smaller than a tic-tac. But that frozen fragment in a Siberian cave revealed a ghost species that left almost no fossils, yet still lives on inside the DNA of millions of people today.

This episode explores the Denisovans, an extinct branch of humanity that roamed Asia for hundreds of thousands of years. We trace how genetics and protein analysis identified them, what they looked like, how they lived, and how their ancient interbreeding rewrote the human origin story from a straight line into a braided river.

• How a 2010 genome from a single finger bone revealed a hominin distinct from both modern humans and Neanderthals
• Paleoproteomics identifying the Tibetan Xiahe jawbone and the dramatic Harbin 'Dragon Man' skull as Denisovan
• Evi ...