Why, according to scientists, are all blue-eyed people on Earth the descendants of one person?

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

From what little we’ve learned, we know that blue eyes are a recessive gene, meaning you have to have two of them for the color to show. So a blue-eyed individual inevitably has two “blue-eyed” copies of the gene. Because of this, inevitably, blue-eyed parents each give their child a variable version of the same “blue-eyed” gene.

But if you’re wondering where exactly these genes come from, one study found that they can only be attributed to 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 have blue eyes.

And now the rarity of this color makes sense, as scientists have found that the genetic mutation likely came from a human who lived 6,000 to 10,000 years ago.

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

blue eyes

However, it turns out that the genetic mutation that causes blue eyes comes from an entirely different gene called HERC2, which disables OCA2 entirely and “dilutes” brown to blue. A mutation in the HERC2 gene alongside OCA2 affects the iris of humans and is common to all people with blue eyes.

And how do they know it’s all connected to a common ancestor?

Because every blue-eyed person has the same mutation.

Although much research remains to be done, it is believed that the mutation may have spread when people migrated from Africa to Europe, which would partially explain why people of European descent are most likely to have blue eyes.

The discovery was actually made in 2008 when a team of researchers from the University of Copenhagen first tracked down the mutation.

blue-eyed people

To date, the first blue-eyed person ever found belongs to a 7,000-year-old skeleton discovered in northern Spain. Of course, the eyes had long since decomposed, but genetic analysis revealed that they would have been blue.

The fact that every blue-eyed person alive today has the same mutation is fairly compelling evidence for this theory, although the reason for this mutation remains a mystery.

The study also looked at variations in other, less common eye colors like green, supporting the idea that an individual is the source of the blue-eyed 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 having a reduced amount of melanin in the iris, which is very different from those 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.

Bottom line: people with blue eyes have a common ancestor, and green eyes have reduced melanin in the iris.

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