New research shows that all blue-eyed people share a common ancestor. This person lived more than 6,000 years ago and carried a genetic mutation that has now spread across the world.

The exact cause remains to be determined but scientists do know that eye color began to change long before recorded history began. The following is a transcript of the video.

All blue-eyed people have one ancestor in common, born around 6,000-10,000 years ago. Blue eyes are caused by a gene mutation. For years, researchers had searched for it on the OCA2 gene. The OCA2 gene determines how much brown pigment is in our eyes. But what they were looking for wasn’t there at all.

The mutation was found on an entirely different gene called HERC2. HERC2 turns off OCA2, meaning it turns off the brown and reveals the blue. Every blue-eyed person has this exact same mutation.