Why are all blue-eyed people on Earth descended from one person, according to scientists?

For blue-eyed people, it turns out that they all share an ancestor, which can be information that will make other blue-eyed people you’re trying to attract a bit awkward.

From what little we’ve learned, we know that blue eyes are a recessive gene, meaning you have to have two for the color to show up. Therefore, a blue-eyed individual necessarily has two copies of the “blue-eyed” gene. This is why blue-eyed parents will necessarily each give a variable version of the same “blue-eyed” gene to their child.

But, if you’re wondering where exactly these genes come from, one study found that they can be attributed to just one person.

We know that blue eyes are much rarer than brown eyes, it is estimated that between 8 and 10% of the world’s population has blue eyes.

And now, the rarity of this color makes sense, as scientists have revealed that the genetic mutation is believed to come from a human who lived between 6,000 and 10,000 years ago.

Researchers have been trying to find out what caused this change by studying the OCA2 gene, or protein P, which determines the level of brown pigment in the human eye, for many years.

blue eyes

However, it turns out that the genetic mutation that causes blue eyes comes from an entirely different gene called HERC2, which turns off OCA2 entirely and “dilutes” brown to blue. A mutation in the HERC2 gene adjacent to OCA2 affects people’s irises and is common to all people with blue eyes.

And how do they know that everything is linked to a common ancestor?

Because all blue-eyed people have the same mutation.

Well, what remains of encore beaucoup de recherches à faire, I think that the mutation aurait pu se spread lorsque les humains ont migré d’Afrique vers l’Europe, ce qui expliquerait en partie pourquoi les personnes d’origine européenne ont le plus souvent blue eyes.

The discovery was actually made in 2008, when a research team from the University of Copenhagen initially located the mutation.

blue eyed people

To date, the first blue-eyed person found belongs to a 7,000-year-old skeleton discovered in northern Spain. Naturally, the eyes had been decomposing for a long time, but genetic analysis revealed that they would have been blue.

The fact that all blue-eyed people alive today have this same mutation is pretty compelling evidence for this theory, although the reason for this mutation remains a mystery.

The study also looked at variation in other less common eye colors, such as green, which supported the idea that one person is the source of the blue eye gene.

Study author Professor Hans Eiberg, from the Department of Cellular and Molecular Medicine, told Science Daily:

blue eyed people

“People with green eyes can be explained by the fact that they have a reduced amount of melanin in the iris, which is very different from people with blue eyes. »

“From this we can conclude that all blue-eyed individuals are related to the same ancestor. They all inherited the same switch at exactly the same place in their DNA,” he concluded.

To conclude: people with blue eyes share an ancestor, and green eyes have reduced melanin in the iris.

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