New research reveals that people with blue eyes have (single) common ancestor. Previously we all had brown eyes, but 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.
The OCA2 gene codes for the P protein, which is involved in the production of melanin pigment that gives color to our hair, eyes, and skin. The "switch," which is found within the gene adjacent to OCA2, however does not, turn off the gene totally, but rather limits its action to lessening the production of melanin within the iris successfully i.e; "diluting" brown eyes to blue. The switch's impact on OCA2 is exceptionally specific.
In addition to having significantly less melanin in their iris than people with brown eyes, hazel eyes or green eyes, blue-eyed individuals have only a little degree of variation in their genetic coding for melanin production. Brown-eyed people, on the other hand, have significant individual variation within the area of their DNA that controls melanin production. From this, the researchers conclude that all blue-eyed individuals are linked to the same ancestors and they all have inherited the same switch at exactly the same spot in their DNA.
In addition to having significantly less melanin in their iris than people with brown eyes, hazel eyes or green eyes, blue-eyed individuals have only a little degree of variation in their genetic coding for melanin production. Brown-eyed people, on the other hand, have significant individual variation within the area of their DNA that controls melanin production. From this, the researchers conclude that all blue-eyed individuals are linked to the same ancestors and they all have inherited the same switch at exactly the same spot in their DNA.
The color of our eyes depends on the amount of melanin is present in the iris. There's only brown color within the eye — there's no hazel shade or green shade or blue color. Brown eyes have the highest amount of melanin within the iris, and blue eyes have the slightest.
Risks Associated With Blue Eyes
Risks Associated With Blue Eyes
As blue eyes contain less melanin as compared to hazel, brown and green eyes they are more susceptible to damage from UV and blue light because melanin in the iris protects the back of the eye from the damage caused by UV radiation and high-energy visible ("blue") light from sunlight and artificial sources of these rays.
Research has shown that blue eye colour is associated with a greater risk of age-related macular degeneration (AMD) and a rare but potentially deadly form of eye cancer called uveal melanoma.
For these reasons, people with blue eyes should be more cautious regarding their exposure to sunlight.
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