A genetic mutation over 6,000 years ago is the cause of all blue-eyed people.
As explained in our article on the different colors of the eyes, it is a cocktail of 16 genes as well as the difference in melanin concentration in the tissues of the iris that determine the color of our eyes.
It would seem that in the beginning of human beings, all people had dark eyes.
Researchers from the University of Copenhagen have looked into the origin of blue eyes.
It seems difficult to accurately estimate the year during which the first blue eyes were recorded since these researchers estimate it between 6,000 and 10,000 years ago. It was there that a European baby was born with a harmless genetic mutation, an eye color transformation.
This genetic mutation somehow blocks the ability to produce brown eyes by limiting the production of melanin in the iris, which effectively "dilutes" brown eyes to a shade of blue. This identified OCA2 gene, if it is destroyed leads to an absence of melanin in the hair, iris and skin known as albinism.
People with blue eyes also seem to show little variation in the part of their DNA responsible for melanin production, whereas those with brown eyes have much more.
It is for these and other reasons that scientists believe that this baby born thousands of years ago is the common ancestor of all blue eyes.
May all blue-eyed people be reassured, this genetic mutation is not negative. It has as little impact as those causing freckles, moles, baldness, etc.