ALL blue-eyed people descend from a single European ancestor who lived between 6,000 and 10,000 years ago, research has revealed.

Originally, all humans had brown eyes, until a European developed a specific mutation which resulted in a widespread iris colouration.

The genetic variation of the gene OCA2 changed the amount of pigment people produced, which slightly changed the shade of their brown eyes.

But despite knowing this information about the OCA2 gene, scientists couldn't find the source of the blue pigment, until now.

After studying the mutated gene HERC2, scientists found this to be the cause of blue eyes because it switches off OCA2, the gene that determines how much brown pigment melanin to make.

Scientists believe this to have happened when people migrated from Africa to Europe, meaning all blue-eyed humans share a single European ancestor.

This theory is supported by the fact that every blue-eyed person shares the same mutation; unfortunately the identity of the ancestor is unknown.