It’s said that the eyes are the window to the soul. When viewed up close, it is easy, however, to note that the eyes are far from being transparent. If you’ve ever looked at up-close images of the iris, you may have noticed incredible patterns. These patterns resemble stormy skies, thriving trees, or crystal blue waters.
What you see is dependent upon the color of the iris. You’re not alone if you’ve ever wondered why some people have brown, blue, green, or any other color. Many scientists have conducted several studies revolving around the origin of blue eyes, and their discoveries have led to the conclusion that people with blue eyes all have a common ancestor.
Blue Eye Discovery
As it turns out, all people with blue eyes have more than just blue eyes in common. Scientists have learned that people with blue eyes are all descended from the same person, meaning all share an ancestor. This ancestor lived anywhere from 6,000 to 10,000 years ago. Prior to that, there were no blue eyes, only brown, according to Hans Eiberg from the department of cellular and molecular medicine.
His research is done at the University of Copenhagen. [1] Eiberg and his team examined DNA and found a genetic mutation thus creating blue eyes. “A genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a ‘switch,’ which literally ‘turned off’ the ability to produce brown eyes,” Eiberg said.[1] The study looked at individuals from many countries including several from the Middle East.
Scientists looked at patterns found within DNA, specifically the OAC2 gene to find out how to “turn down” melanin production. [1] The mutation discovered by scientists was discovered to be on an entirely different gene called HERC2. This gene is what “turns off” OCA2. This inhibits brown pigments, revealing various shades of blue. [6]
More than one study has been done over the years. John Hawks of the University of Wisconsin-Madison was not a researcher for the first study conducted. However, he has taken part in the research conducted since 2008, when the original study was done. He said of the discovery, “What they were able to show is that the people who have blue eyes in Denmark, as far as Jordan, these people all have this same haplotype, they all have exactly the same gene changes that are all linked to this one mutation that makes eyes blue.”[1]
Essentially these findings show that every person with blue eyes has the same ancestor. Only one person experienced this genetic mutation and then passed the genes onto their offspring for generations to come.
A Brief Look at the Science of DNA
The DNA observed for this study came from the mitochondria, which are energy-producing structures within cells. This mutation impacts a gene called OCA2. OCA2 is the gene responsible for the production of melanin. Melanin gives color to our skin, eyes, and hair, so the coloration and differences of each person are dependent upon how much or how little melanin is produced. This amount varies from person to person and is deeply rooted in our ancestral pasts.
Throughout generations, DNA gets shuffled and its structure changes causing a variety of results. These DNA chains, scientifically known as Polynucleotides, sometimes do not shuffle their order. There is a multitude of reasons this might happen and the result is known as “haplotypes”[1]. In this case, the DNA sequence didn’t have enough time between generations to become mixed up.