New research shows that all blue-eyed people are the descendants of one single human who lived thousands of years ago.
Although blue is the second most common eye color among humans in the world, it is still uncommon as compared to the usual black and brown, and only 8-10% of people have blue eyes.
But how did this mutation occur? Well, it is still a genetic mystery.
The exact reason is yet to be determined. Still, according to a group of students from Copenhagen University, a single mutation that occurred nearly 6,000 years ago was responsible for this unique eye color.
“All blue-eyed people have one ancestor in common, born around 6,000 to 10,000 years ago. Blue eyes are caused by a gene mutation. For years, researchers had searched for it on the OCA2 gene. The OCA2 gene determines how much brown pigment is in our eyes. But what they were looking for wasn’t there at all,” Insider wrote.
The team identified a single mutation that occurred by chance in a gene called OCA2 almost 8,000 years ago near the coast of the Black Sea in one single in one human individual.
According to the team leader, Dr. Hans Eiberg,
“The gene does not make blue in the iris; rather, it turns off the mechanism which produces brown melanin pigment. Originally, we all had brown eyes.”
The research involved families that included members with blue and brown eyes (parents and children).
“And families whose irises show blue- and green-spot segregation were excluded; all in all, 100 families were included in the analysis. Out of these, 45 families had at least one individual with brown eyes, and 55 were composed exclusively of blue-eyed members,” quoted ZME Science.
“Two individuals born with heterochromia (who have eyes of different colours) were also included in the analysis. Genetic material from individuals from Turkey and two from Jordan was also used in the study.”
The team then examined participants’ DNA and mitochondrial DNA to determine the mutation that is most likely responsible for blue eyes. They found that this mutation affects an allele known as the OCA2 gene.”
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Sources: Insider – ZME Science
