Blue-eyed individuals share common ancestor, claims genetic research

Copenhagen, Denmark

A study conducted by a team at the University of Copenhagen has shed light on the origins of blue eyes. As per the findings of the research all blue-eyed individuals are may be sharing a single and common ancestor.

The research, led by Professor Hans Eiberg from the Department of Cellular and Molecular Medicine, pinpointed a genetic mutation that occurred 6-10,000 years ago. This mutation led to the emergence of blue eyes among humans.

The genetic mutation in question affected the OCA2 gene.

The OCA2 (oculocutaneous albinism II) gene provides instructions for making a protein called the P protein. This protein is primarily found in melanocytes, which are specialised cells involved in producing melanin, the pigment responsible for the colour of the skin, hair, and eyes.

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Mutations in the OCA2 gene can lead to changes in the P protein, which can affect the production and distribution of melanin. This can result in conditions such as oculocutaneous albinism, where individuals have little to no melanin production, leading to very fair skin, light-coloured hair, and light-coloured eyes.

The OCA2 gene is also associated with variations in eye colour in the general population, as different versions of the gene can influence the amount and distribution of melanin in the iris which can result in different eye colours.

Genetic mutation 

A genetic mutation affecting the OCA2 gene in our chromosomes resulted "in the creation of a 'switch' which 'turned off' the ability to produce brown eyes," as per the study.

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This switch, located adjacent to the OCA2 gene dampers the gene's ability to reduce melanin production. "From this we can conclude that all blue-eyed individuals are linked to the same ancestor," Professor Eiberg stated.

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Examining mitochondrial DNA and comparing eye colour across different countries, including Jordan, Denmark, and Turkey, Professor Eiberg and his team confirmed their findings.

Regarding the significance of the mutation, Professor Eiberg emphasised that it neither confers a positive nor negative impact on survival. "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," he said.

(With inputs from agencies)