Eye color is one of the most striking and variable physical traits among humans. The color of our eyes results from the amount and type of pigment in the iris. Two pigments in particular determine eye color – melanin and lipochrome. The amount of these pigments present is what leads to the wide range of eye shades, from dark brown to light blue. When it comes to more rare eye colors like green and hazel, the specific combinations and variations in these pigments produce their distinct hues. So which is actually more uncommon – green or hazel eyes?
The Genetics Behind Eye Color
The primary gene responsible for eye color is the OCA2 gene, which controls the production of melanin pigment. The specific alleles, or variants, of this gene present determine how much melanin is produced. Those with two copies of the allele for high melanin production tend to have brown eyes, while those with less melanin have blue, green or hazel eyes.
The lipochrome pigment also influences eye color, especially for green and hazel eyes. This yellowish pigment provides the distinct green hue of green eyes. Hazel eyes derive their color from a combination of melanin and lipochrome. The interplay between these two pigments and the specific combinations of OCA2 alleles leads to the range of green and hazel shades.
Global Distribution of Eye Colors
On a global scale, brown eyes are by far the most common. An estimated 70-90% of the world’s population has brown eyes. This includes Central and South America, most of Africa, and Asia.
Blue, green and hazel eyes are rare worldwide but more common among people of European ancestry. Overall, blue eyes make up around 8-10% of the global population. But in countries like Ireland and Finland, up to 90% of the population has blue eyes.
Green eyes are rarest and estimated to occur in only 2% of the world population. Hazel eyes are also quite uncommon at around 5% globally. Among European populations, hazel eyes make up about 10-15%.
Breakdown by Country and Region
Here is a more detailed breakdown of green and hazel eye color percentages by country and region:
| Country/Region | Green Eyes | Hazel Eyes |
|---|---|---|
| United States | 2% | 5% |
| United Kingdom | 3% | 11% |
| Ireland | 10% | 17% |
| Finland | 4% | 10% |
| Iceland | 9% | 29% |
| Norway | 3% | 12% |
| Sweden | 2% | 11% |
| Spain | 2% | 7% |
| Italy | 1% | 4% |
This data shows some clear patterns in the distribution of these rarer eye colors:
– Green eyes occur with higher frequency in Northern Europe, particularly Ireland, where almost 1 in 10 people have them. Scandinavian countries like Finland, Norway and Sweden also have slightly higher percentages of green compared to Southern Europe.
– Hazel eyes follow a similar pattern, being most common in Northern Europe. Nearly 30% of Icelanders have hazel eyes, along with 11-17% of Brits and Irish. Hazel eyes are rarest in Italy and Spain.
– The United States has small but significant populations of those with green and hazel eyes, likely due to high levels of Northern European ancestry.
Is Green or Hazel More Rare?
Based on all the available data, hazel eyes appear to be slightly less rare compared to green eyes. While both are uncommon, hazel eyes tend to have higher percentages globally and across different European populations.
The key reasons hazel eyes are more common than green are:
– Wider range of possible shades. Hazel includes combinations of brown, green, gold and orange. This increases the possibilities of having hazel eyes.
– Green eyes depend on very specific melanin and lipochrome levels. Slight variations alter the hue outside of true green.
– More potential allele combinations can produce hazel eyes. The particular OCA2 alleles needed for bright green are rarer.
– Geographic distribution favors hazel eyes. Patterns of human migration and settlement led to higher concentrations of hazel compared to green in key ancestral populations.
While the percentages for both eye colors are small globally, hazel eyes appear to occur at slightly higher rates overall, making them marginally less rare than green eyes.
Predictions for the Future
What might happen to the comparative rarity of green and hazel eyes in the future? Here are a few possibilities:
– Increased mobility and immigration could diversify local gene pools. This could raise the incidence of rare eye colors in areas where they have historically been uncommon.
– Climate change may impact geographic distribution if certain populations migrate. For example, Northern Europeans moving South could increase green/hazel eyes in those areas.
– Genetic engineering or gene therapy may one day allow people to alter their eye color. This could significantly increase the overall percentages of green and hazel eyes if chosen for aesthetic reasons.
– Changes in social perceptions of desirable eye colors, driven by celebrity culture and media, can influence mating preferences and partner selection.
– Natural selection pressures related to eye color genes are minimal today, but environmental changes or catastrophes could impact relative distributions.
While predicting small genetic shifts is difficult, it’s likely that the rarity of green and hazel eyes will decrease somewhat over time due to increased diversity and potential technology. But the uniqueness of these striking eye colors will persist well into the future.
Conclusion
Green and hazel eyes are globally uncommon, with hazel eyes slightly less rare compared to green overall. The distinct hues arise from unique combinations of melanin and lipochrome pigments. Geographic patterns favor hazel in key ancestral populations, though both colors remain quite unique. Advances in society and technology may slowly increase the percentages of these eyes colors, but their rarity and allure will continue. So while hazel edges out green in terms of frequency, both remain exceptionally beautiful and exotic eye colors.
