Facts About Blue Eyes
Sometimes it seems like almost everyone in show business has blue eyes. From Frank Sinatra and Paul Newman to Emma Stone, Jake Gyllenhaal, and Taylor Swift, the number of Hollywood stars with brilliant blue eyes is almost endless. In reality, the number of people with blue eyes is quite small. Interestingly, most scientists believe blue eyes are the result of a rare genetic mutation that occurred thousands of years ago.
To learn more about the uniqueness of blue eyes, check out these fun facts below.
How Many People Have Blue Eyes?
The most recent research suggests roughly 10 percent of the global population now has blue eyes. That’s far less than brown eyes (almost 80 percent), but not as rare as green, grey, or hazel eyes (all of which are well below 5 percent).
Blue eyes are only found in people with at least some European ancestry in their bloodline. Indeed, many nations in Northern and Eastern Europe have populations where the majority of citizens have blue eyes. Currently, almost 90 percent of people in Estonia and Finland have blue eyes.
In the UK, blue eyes are still the most common eye colour in many regions. This is especially true in Scotland and Ireland where over 50 percent of native born citizens have blue eyes. The rates of blue eyes dip the further south you go in Wales and England, but averages remain above 35 percent.
Everyone With Blue Eyes Has A Common Ancestor
According to new research out of the University of Copenhagen, everyone who has blue eyes can trace their family tree all the way back to one person. Danish geneticists say blue eyes are the result of a genetic mutation in one European between 6,000 and 10,000 years ago. Before this first blue-eyed individual reproduced, it was believed everyone on earth had dark brown eyes.
Apparently, people with blue eyes have a faulty OCA2 gene. Turning off this gene makes it impossible for the eyes to express brown, hence the appearance of blue eyes.
Since blue eyes were such a novelty, scientists theorise that European ancestors actively sought out partners with this genetic defect. As we’ve seen above, blue eyes have now become extremely common in many European nations.
Anyone who’s interested in reading this entire study can find it in the journal Human Genetics Volume 123, Issue 2. This study was listed under the title, “Blue eye colour in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression.”
Blue Eyes Aren’t Really Blue
In reality, all eye colours are simply a different shade of brown. People who have rare eye colours such as blue only have less of the brown pigment melanin in their irises.
The more melanin a person has, the more likely they will have dark brown eyes. People with slightly less melanin than brown-eyed people might have hazel, green, or amber eyes. Finally, people with very little melanin often have what appear to be blue or grey eyes.
How we perceive eye colour is all about how much light gets absorbed in or reflected out from the iris. Melanin absorbs light, so having less of this pigment in your eyes will allow more light to be reflected outwards and cause your eyes to look lighter.
Can We Predict Blue Eyes?
In the not-too-distant past, geneticists believed that two parents who had blue eyes must have a child with blue eyes. Statistical data now proves that this is far from the case. In fact, many blue-eyed parents have children with dark brown eyes! How can we explain that?
This new info has complicated scientists’ notions of genetic inheritance. Instead of the dominant-recessive model, geneticists admit that genetic influences and mutations are far more complex than they previously imagined.
While using more simplistic genetic models could help predict the likelihood of a certain trait like eye colour, geneticists say we have no way to account for all the genetic interactions that might influence a child’s eye colour. For people who are interested, however, there are many high-quality genetic predictors online.
Blue Eyes At Birth…But Not For Life
You may have noticed that many blue-eyed babies don’t have the same brilliant eye colour as they grow up. The reason this happens is that it takes a few months for our irises to develop their full colour.
As the child’s eyes take in more melanin, their eyes become darker. Usually, a child’s eye colour is set after a few years, so you’ll just have to wait to find out what colour your child’s lifelong eyes are going to be!
Risks Of UV Exposure For Blue Eyes
Besides changing the colour of our eyes and skin, melanin can block the sun’s harmful ultraviolet (UV) rays. People with blue eyes don’t have this additional protection, which makes it easier for UV rays to penetrate the iris and cause a whole host of issues. Over time, this increased exposure to UV rays could lead to serious eye disorders like age-related macular degeneration or eye cancer.
It’s important for people with blue eyes to wear some form of UV protection whenever they’re outside. Even if it’s not sunny out, your eyes are still being exposed to UV rays. By wearing UV-blocking eyewear, you’ll dramatically reduce your risk of developing sight-robbing disorders.
Blue Eyes And Blue Light
In addition to UV exposure, people with blue eyes need to be extra careful when staring at electronic screens. Although scientists are still researching the effects of prolonged blue light exposure, most believe this light wave has a deleterious effect on eye health. Some scientists believe prolonged blue light exposure dramatically increases the risk for disorders like dry eye syndrome and myopia.
Since blue-eyed people have less melanin to shield their eyes, they could consider investing in special glasses that deflect blue light. It’s also important to take regular breaks from staring at computer screens to give your eyes a chance to naturally re-hydrate.
Blue Eyes And Alcoholism: Is There A Link?
The most shocking health risk of having blue eyes is that it could increase your likelihood of becoming an alcoholic. According to research Joel C. Eissenberg PhD people with blue eyes are more likely to develop an addiction to alcohol compared with other eye colours.
He found that one of the reasons blue-eyed people had a greater chance of developing alcoholism was that a gene lying near the OCA2 gene on chromosome 15 carries a mutation that leads to increased alcohol tolerance.
For more information on this research, you can find the full study in the April 2015 edition of the American Journal of Medical Genetics: Neuropsychiatric Genetics (Part B). This study was entitled, “Eye colour: A potential indicator of alcohol dependence risk in European Americans.”
Don’t Have Blue Eyes? Try Coloured Contact Lenses!
Since blue eyes are relatively rare and popular in the entertainment industry, it’s no wonder people who weren’t born with this eye colour are interested in wearing blue contact lenses.
Coloured contact lenses are available to correct your vision or with no vision correction. Before purchasing coloured contact contacts, it’s important to see an optometrist to get a contact lens fitting. Even if you don’t wear corrective eyewear, you need a professional measurement before ordering decorative lenses.
Once you have your measurement data, you can ask to experiment with various coloured contacts. As with all contact lenses coloured lenses require a bit of looking after, which includes washing your hands before placing them in your eyes, placing lenses in solution, throwing lenses away after their wear time, and removing lenses before you swim, shower, and sleep. For more information on how to take care of contact lenses, check out our helpful guides on cleaning, insertion and removal.
Not only will wearing improperly fitted contact lenses cause eye discomfort, could also cause significant damage to your eyes in the form of scarring and infections.
Now You Know About Those Beautiful Blue Eyes
Blue eyes certainly are beautiful, but that beauty has a few unexpected risks. If you were lucky enough to be born with these eyes, then you need to be extra careful with UV and blue light exposure. On the other hand, those who want blue eyes should schedule an appointment with an optometrist to get a proper contact lens fitting.
Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 27 Apr 2023, Last modified: 4 May 2023