New research suggests that all blue-eyed people share a common ancestor who lived more than 6,000 years ago and carried a genetic mutation that has now spread across the world.

The exact cause remains to be determined, but scientists do know that eye color began to change long before recorded history began.

Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes.

All Blue-Eyed People Have a Single Ancestor in Common
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.

Taylor Swift, Jennifer Lawrence, Gwyneth Paltrow, Michael Ealy, Chris Pine, Jake Gyllenhaal, Alexis Bledel, Jessica Steen, Cameron Diaz, and Ian Somerhalder to name a few all have blue eyes.

All blue-eyed people have a single ancestor in common

The mutation was found on an entirely different gene called HERC2. HERC2 turns off OCA2, meaning it turns off the brown and reveals the blue. Every blue-eyed person has this exact same mutation.

How did this mutation get its start? Possibly when humans migrated from Africa to Europe. This would explain why only people of European descent have blue eyes. It would also suggest that all blue-eyed people share a single European ancestor.

All blue-eyed people have a single ancestor in common

Because blue eyes contain less melanin than green, hazel or brown eyes, they may be more susceptible to damage from UV and blue light. Melanin in the iris of the eye appears to help protect the back of the eye from 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 color 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.

All blue-eyed people have a single ancestor in common

For these reasons, people with blue eyes should be extra cautious regarding their exposure to sunlight. And because eye damage from UV and blue light appears to be related to your lifetime exposure to these rays, wearing sunglasses that block 100 percent UV and most blue light should begin as soon as possible in childhood.

Photochromic lenses are another great way to protect blue eyes from UV radiation. These clear lenses block 100 percent UV both indoors and outside, and darken automatically in response to sunlight when outdoors so there’s no need to carry a separate pair of sunglasses.

All blue-eyed people have a single ancestor in common

Also, adding anti-reflective coating to photochromic lenses gives the best vision and comfort in all lighting conditions (including driving at night) while showcasing blue eyes with reflection-free lenses.

AR coating is recommended for all types of eyeglass lenses — including single vision, bifocal and progressive lenses — to eliminate distracting reflections and allow people to see the beauty and expressiveness of blue eyes.

All blue-eyed people have a single ancestor in common

For blue-eyed people who spend several hours a day using a computer, smartphone or other digital devices, it’s a good idea to wear eyeglasses to shield the eyes from high-energy blue light when using these devices.

It may take many years before we know the risks associated with cumulative exposure to blue light from computers and smart phones. But many eye care professionals believe it’s prudent to use caution when it comes to protecting your eyes from these devices — especially if you have blue eyes.

All blue-eyed people have a single ancestor in common

Research suggests that having blue eyes may increase your risk of alcohol dependency if you are a drinker. A study published in American Journal of Medical Genetics, Part B: Neuropsychiatric Genetics found that European Americans with blue eyes had up to 83 percent higher odds of becoming dependent on alcohol, compared with matched controls who had darker eye colors.

Photography: Jaguar PS, Everett Collection, Joe Seer, Featureflash Photo Agency / all at Shutterstock.com