Study Finds All People With Blue Eyes Have A Single, Common Ancestor

Have you ever wondered where blues come from?

It’s a question that’s boggled individuals and research teams alike.

Photo: Unsplash/Erik Mclean

According to the Cleveland Clinic, up until some 10,000 years ago, it’s believed everyone in the world had brown eyes. Now, an estimated 8-10% of people in the world have blue eyes.

How did that come to be?

As it turns out, researchers now believe blue eyes all started with a single person who passed on a genetic mutation that spread across the world. In other words, everyone with blue eyes shares a single, common ancestor.

Photo: Unsplash/Hadis Safari

Back in 2008, researchers with the University of Copenhagen examined the exact genetic mutation that resulted in blue eyes all those years ago. Their research was published in the The Journal of Human Genetics.

According to Science Daily, the study’s lead author, Professor Hans Eiberg, explained that humans originally had brown eyes, and a gene mutation “turned off” the ability to produce brown eyes – resulting in some people having blue eyes.

Photo: Unsplash/Juan Goyache

The press release elaborated that the affected gene, the OCA2 gene, regulates brown pigment in the eyes. If the OCA2 gene had been completely destroyed or “turned off” then the affected humans would be without any melanin in their hair, eyes, or skin color (a condition known as albinism). But with the specific mutation, the body has a limited ability to produce melanin in the iris, resulting in a blue iris, rather than a brown iris.

The genetic mutation isn’t a positive or negative trait. As Eiberg explained, mutations can affect things like freckles, balding patterns, hair color, and more. He 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.”

According to the College of Physicians of Philadelphia, researchers studied the mitochondrial DNA of individuals with blue eyes from various countries, such as Jordan, Denmark, and Turkey. The researchers found that over 97% of the blue-eyed people in the study shared a single haplotype – a grouping of genomic variants that are usually inherited.

Photo: Pexels/Jenna Hamra

Because of this, researchers believe that the mutation is passed on genetically, meaning that everyone with blue eyes is related.

In a press release, shared in EurekaAlerta!, Eiberg explained, “From this, we can conclude that all blue-eyed individuals are linked to the same ancestor. They inherited the same switch at the same spot in their DNA.”

So, there you have it!

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