Every single person with blue eyes can trace their lineage back to one common ancestor. This week, we explore the genetic mutation on the OCA2 and HERC2 genes that occurred between 6,000 and 10,000 years ago, turning off the melanin production that creates brown eyes.

We discuss how this "genetic switch" spread across Europe and why blue eyes are actually colorless structures that rely on scattered light to be seen. From the shores of the Black Sea to modern genetics, we tell the story of one of humanity's most distinct traits.