You’d be right, if you thought the most common eye color in the world is brown. A large portion of everyone on earth is brown-eyed. In certain parts of the world, brown is about the only eye color you’ll find.
Just like skin color, eye color is another remarkable inter-individual difference in humans. Did you know that you are more likely to meet people with brown eyes as you travel towards the earth’s equator? On the other hand, you are less likely to meet a brown-eyed person as you travel toward the earth’s poles.
What Percentage of Humans Have Brown Eyes?
To better appreciate the proportion of the world’s population with brown eyes, we need to talk in terms of percentages.
Take more than 150 million people in the US with brown eyes; this makes up almost half of the US population. Add pretty much everyone in Africa (> 1.2 billion people) and Asia (> 4.4 billion people); they all have brown eyes – most of them at least. All these combined already equals more than half of the world population, without counting lots of brown-eyed people living in South America, Australia and Russia.
It therefore makes sense to estimate the true percentage of brown-eyed people to be between 70% and 90% of the world’s population. This implies that there are more people on earth with brown eyes than all the other eye colors combined.
So, even though it is hard to find reliable statistics on the distribution on eye colors, one can still say with confidence that brown is the most common eye color in the world.
6 Things You Should Know About Brown Eyes
The brown eye color has been associated with the following variables:
- Lower pain tolerance
- Increased susceptibility to alcohol
- Lower sensitivity to bright light
- Lower night vision
- Lower risk for certain diseases
- Quicker reaction time
Tolerability to Pain
A study conducted by the University of Pittsburgh (UPMC) uncovered interesting information about potential effects of eye color on humans . In an effort to gain more knowledge on the relationship between genetics and pain tolerance, 58 healthy pregnant women were studied in 2 groups based on eye color; light-colored versus dark-colored eyes.
The women were evaluated for pain immediately before and after labor. Women with light colored eyes such as blue and green were found to tolerate pain better than their dark-eyed counterparts (brown and hazel). The UPMC team also evaluated mood and sleep and found that the group of women with blue and green (light-colored) eye color had a lower depression rate and decreased sleep disturbance than the dark-eyed group.
This does not mean we can now use a woman’s eye color to predict the severity of her labor pains. The study was merely exploratory; there is still a lot to be done before drawing solid conclusion.
Susceptibility to Alcohol
Did you know brown-eyed people are more susceptible to alcohol? Apparently, this is due to their higher melanin concentration. In case you don’t know, melanin is a brown pigment that is responsible for giving you a nice tan after a long day at the beach.
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There have been numerous reports about potential relationships between eye color and behavior. In a large study that recruited more than 10000 men and women, the research team of the department of psychology of Georgia State University found that light-eyed subjects were less sensitive to alcohol and hence consumed significantly more buzz than dark-eyed subjects. They concluded that the greater sensitivity to alcohol in dark-eyed folks prevents them from drinking so much as to develop an addiction.
Bottom line, the study showed that light-eyed people are more likely to abuse alcohol than dark-eyed people .
Sensitivity to Light
Melanin is thought to protect the eye by absorbing a great deal of the light that enters the eyeball. The more melanin the eye has, the lesser it will be assaulted by cosmic rays from the sun. This means that dark-eyed people have more melanin and hence are less sensitive to bright light than light-eyed people. Albinos are the most sensitive to light; they have little to no melanin .
Folks with blue eyes have a better night vision than those with dark-colored eyes. Even though this strikes many as contentious, it is a hypothesis that seems to make sense from an evolutionary stand point. Looking at the distribution of blue-eyed people in the world, the farther north you go there more likely you’ll find someone with blue eyes. It is believed that blue eyes help man and animal navigate their habitat during the long dark winter months of the northern hemisphere.
While experts are still bridging gap between the night vision myth and solid scientific insight, let’s take a poll.
Do people with brown eyes have better reaction time? This interesting theory was investigated by the University of Louisville, in a study that grouped light-eyed and dark-eyed individuals to compare their performances . They found that dark-eyed subjects had better reaction time and motor skills when performing tasks such as hitting a ball or boxing. Light-eyed subjects were better at tasks such as bowling and golf.
Even though it has been reported in several studies, the claim that brown-eyed people have higher reaction time still remains controversial.
Susceptibility to Certain Diseases
There are several factors that have been linked to macular degeneration (MD), these include eye color. MD is a disease that affects the central vision of the eye due to deterioration of the eye’s macula. This is the main cause of vision loss amongst the elderly
MD is more common in people with blue and green eyes . This means that if you have blue eyes then you have a higher chance of developing MD than someone with brown eyes. Furthermore, if you have blue eyes and someone in your family has MD then your chance of developing MD increases even further.
Green eyes have also been associated to hearing loss.
While you can't change your genes or eye color, there are other lifestyle habits you can change to improve your chances of developing a disease such as MD. You could start with protecting your skin and eyes from the harmful rays from the sun, eat right, keep fit and stay healthy.
Dave on January 01, 2018:
Most on-line sources list the probability of brown eyes at 55% but that must be for US only. If nobody but Asians and Africans had brown eyes, the global brown-eyed percentage would be about 80% and if the rest of the world had a 50% chance of brown, the global percent would be 90%, which is probably pretty accurate. In other words, globally, you have a 1 in 10 chance of having non-brown eyes.
Edmund Custers (author) on July 23, 2016:
Hi OLiwia, I have a friend with a (dark) limbal ring around her iris. But the greenish-blue and the brown one around your pupil sounds pretty interesting.
Thank you for stopping by and commenting. I hope you enjoyed this article.
OLiwia on July 19, 2016:
I Have a thin blue line around my eye, than a greenish-blue and around my pupil a brown - How rare is this?
Edmund Custers (author) on June 19, 2016:
Hi Lion44, the intention was not to look only at a specific subgroup, so indeed the list applies across racial lines. thank you for stopping by and commenting. I am glad you found this page interesting.
CJ Kelly from the PNW on June 18, 2016:
Interesting hub. I have brown eyes and always had better night vision than others. My color vision is very weak, which might explain that. But I've always been very sensitive to light.
Would race factor into this at all? I'm white with brown eyes, but would the list above apply across racial and ethnic lines? Endless topic. Thx.