Blue-eyed people all share the same relative who lived 10,000 years ago, scientists say

Scientists have said that every blue-eyed person on Earth is able to trace their ancestry to a single individual who lived between 6,000 to 10,000 years ago.

They have also worked out that long ago all humans had brown eyes, until a specific genetic mutation caused eye-colours to change.

The mutation occurs in a gene called HERC2, where the OCA2 gene is switched off.

This gene regulates the amount of brown pigment in our eyes.

It is believed that the first person with blue eyes lived in Europe, roughly 10,000 years ago, and every person with blue eyes today has the same mutation present in their body.

But it’s a very specific kind of gene mutation, that turns eyes blue, whilst the skin and hair colour retain the same levels of pigment.

A full switch off or if a gene mutation does not produce melanin, it would result in albinism.

The majority of Brits are made up of blue-eyed people with 48%, while 30% are green eyed and 22% have brown eyes.

Whilst there is a big variation between green and brown shades, blue eyes have a tiny variation of the amount of melanin present.

Professor Eiberg, from the University of Copenhagen, suggest that blue-eyed individuals are all linked to the same ancestor.

He said: “They have inherited the same switch at exactly the same spot in their DNA”.

In simpler terms, what eye colour develops works like a wheel of genetic fortunes. Although brown eyes are thought to be the more dominant gene, it is not certain that two brown-eyed parents will have a brown-eyed baby.

It is possible for two brown-eyed parents to have a child with blue eyes and vice versa.

But there are some cases that also tell us that our eye colour doesn’t always remain the same throughout our lives. This can occur due to a wide variety of reasons from injuries to infections and sun damage.

Evidence suggests that whether a baby’s eye colour changes heavily depends on the colour the baby was born with. One study by the Byers Eye Institute at Stanford University, tracked 148 babies recording their eye colours at birth.

The research showed that from the brown eyes babies, blue eyes were more likely to change colour over time, specifically during the early stages.

The research also showed that when babies eye colours did change, it would usually get darker, not lighter.

Professor Eiberg said: “It simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so.”