Light grey eyes are one of the rarest eye colors in the world. They are defined as eyes that are a pale shade of grey, sometimes with a hint of blue. Though not as uncommon as truly black irises, true light grey eyes are nevertheless quite rare globally. Exact statistics on their prevalence are difficult to come by, but most estimates put the percentage of people with light grey eyes at 1-2% of the world’s population. This makes them much less common than brown, blue, hazel, and green eyes. Their striking and unusual appearance has led many to wonder just how rare light grey eyes are and what causes this unique eye color.
What Causes Light Grey Eyes?
Eye color is determined by the amount and type of pigment in the iris of the eye. For most people, this pigment is melanin. The amount of melanin present in the iris is controlled by genetics. Light grey eyes have a reduced amount of melanin in the anterior border layer of the iris, where it absorbs light. This results in an eye color that appears pale grey or blue-grey.
Full albinism is one medical condition that can cause truly grey irises due to a complete lack of melanin. But most light grey eyes occur through normal genetic variation, not albinism. The key gene involved in eye color is OCA2, which codes for the P protein that produces melanin pigment. Certain variations in this gene reduce the amount of melanin produced, leading to light grey eyes.
Global Prevalence of Light Grey Eyes
Globally, brown eyes are by far the most common, with an estimated 79% of the world’s population having them. In contrast, light grey eyes are quite rare in most parts of the world. Here are some estimates on the global prevalence of light grey eyes:
| Region | Estimated Prevalence of Light Grey Eyes |
|---|---|
| Europe | 1-2% |
| United States | 1-2% |
| Africa | Less than 1% |
| Asia | Less than 1% |
| South America | Less than 1% |
As the table shows, light grey eyes are most common in European populations, where they occur in an estimated 1-2% of people. Within Europe, they are most prevalent in Northern and Eastern European countries like Lithuania, Latvia, Finland and Russia, where the gene mutations leading to light eye colors are thought to have originally arisen.
Outside of Europe and North America, true light grey eyes are extremely rare globally. Most other populations have brown eyes as the dominant eye color due to higher melanin levels. Overall, light grey eyes are found in only around 1% of people worldwide.
Are Light Grey Eyes More Common in Certain Groups?
While generally rare, light grey eyes appear to be more common in certain ethnic and demographic groups. Here is an overview of groups that are more likely to have these unique grey/blue iris pigmentations:
– Northern Europeans – Scandinavians, Lithuanians, Finns and Eastern Europeans tend to have the highest percentages of light grey eyes globally. It’s estimated up to 10% of populations in some Northern European countries have this eye color.
– Eastern Europeans – Slavic populations like Russians and Ukrainians also have higher rates of light grey eyes compared to most other groups.
– Caucasians – While rare overall, light grey eyes appear in higher frequencies among Caucasians, especially those of Northern and Eastern European descent. They are less common among Caucasians of Southern European or non-European background.
– Children – Babies often start out with blue/grey eyes due to lack of melanin production. Many will darken over the first few years of life to hazel or brown, but light grey eyes persist more frequently in children than adults.
– Albinos – Those affected by albinism lack melanin production entirely, so grey, blue and red irises are common. But most light grey eyes occur through normal variation, not albinism.
– Females – Light grey eyes are slightly more common in women than men across most populations.
Overall, Northern Europeans, children, and females have the highest chance of having light grey irises, while the trait is exceptionally rare among other ethnicities. But no single group has them as the majority eye color. They remain unusual even among Northern Europeans.
Are True Black Eyes Also Rare?
On the opposite end of the eye color spectrum from light grey are true black eyes. These involve very high levels of melanin pigment in the iris that make it such a dark brown it appears black. This is even rarer than light grey eyes globally. While people of any ethnicity can be born with true black eyes, they tend to be most common in certain groups:
– South Asian populations
– Southeast Asians
– Middle Eastern/North African peoples
– Southern Europeans (e.g. Spanish, Italian, Greek)
– Hispanics/Latinos
– Sub-Saharan Africans
Overall, true black eyes are thought to occur in no more than 2-5% of the global population. That makes them even rarer than light grey eyes overall. But among the groups listed above, their prevalence likely rises to 5-10% or more. They are the most common among people from South Asia and Southeast Asia.
Conclusion
In summary, light grey eyes are considered one of the rarest eye colors globally. While statistics are limited, most estimates suggest they occur naturally in only 1-2% of the world’s population. They arise from genetic mutations that limit melanin production in the iris, resulting in a pale grey coloration with hints of blue. Light grey eyes tend to be most common among those of Northern European descent and children. True black eyes are even rarer than light grey eyes overall. The uniqueness and striking appearance of these opposite ends of the eye color spectrum causes many to wonder just how rare they are. With their limited global prevalence, both light grey and black irises are likely to remain unusual and intriguing sights for the foreseeable future.