A study has found that all humans with blue eyes are descended from a single individual.
A study conducted in 2008 revealed that all people with blue eyes can trace their ancestry back to a single person who likely lived around 10,000 years ago.
According to the analysis by Professor Hans Eiberg and researchers from the University of Copenhagen, over 99.5% of blue-eyed individuals who provided DNA samples have the same small mutation in the gene that determines iris color.
Experts say that humans originally had only brown eyes, but between 6,000 and 10,000 years ago, a single individual with a genetic mutation changed that.
“The mutations responsible for blue eye color likely originated in the northwestern region of the Black Sea, where the major agricultural migration from northern Europe occurred during the Neolithic period, about 6,000 to 10,000 years ago,” the study states.
Speaking to Science Daily, Eiberg explained his findings: “Originally, we all had brown eyes,” he said. “But a genetic mutation affecting the OCA2 gene in our chromosomes created a ‘switch’ that literally turned off the ability to produce brown eyes.”
Eye color variations among people can be explained by the amount of melanin in the iris, but individuals with blue eyes have only a very slight variation in melanin levels.
“From this, we can conclude that all blue-eyed individuals are linked to the same ancestor. They all inherited the same switch at exactly the same spot in their DNA,” said Eiberg.
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