Having hazel eyes is often considered to be quite unique and beautiful. But just how rare is it to have hazel eyes? Let’s take a closer look at the genetics and statistics behind eye color to find out.
What are Hazel Eyes?
Hazel eyes are characterized by having a mix of brown, green, and sometimes gold coloring in the iris. This results in an eye color that can shift between shades of light brown, dark green, amber, and gold. The exact hue can vary greatly from person to person.
Some key things to note about hazel eyes:
– They have a multicolored appearance with a range of brown, green, and gold tones visible in the iris.
– Colors and patterns may be different between the two eyes in some individuals.
– The specific shade can change over time, especially in childhood as melanin content changes.
– Hazel eyes are the result of a genetic mix of variants associated with brown and green eyes.
– They are often confused with amber eyes which have a solid yellowish-brown tone rather than multiple colors.
Genetics Behind Eye Color
To understand the rarity of hazel eyes, we need to first look at how eye color is determined genetically.
Eye color is a polygenic physical trait, meaning it is influenced by multiple genes. The key genes involved are:
– HERC2 – regulates expression of the OCA2 gene and is primarily responsible for brown/blue eye color determination.
– OCA2 – produces the pigment melanin which dictates brown/green eye color.
– SLC24A4 – also involved in melanin production and brown/green eye color.
– SLC45A2 – helps determine melanin content and darker or lighter eye colors.
The specific variants of these genes that a person inherits leads to the development of a particular eye color. The interaction between the OCA2 and HERC2 genes is responsible for brown/blue eye color. The OCA2 and SLC24A4 genes together influence brown/green eye color and melanin content.
Most Common Eye Colors
Using large population databases and surveys, researchers have been able to estimate the prevalence of different eye colors worldwide:
| Eye Color | Global Prevalence |
|---|---|
| Brown | 79% |
| Blue | 8-10% |
| Hazel | 5-8% |
| Green | 2-3% |
| Amber/Gold | ~1% |
| Gray | <1% |
This data shows that brown eyes are by far the most prevalent, with nearly 80% of people worldwide having brown eyes. In contrast, hazel eyes only make up around 5-8% of the global population. This makes them considerably rarer than brown eyes. Hazel eyes are about as common as green eyes, but a bit more prevalent than the very rare amber eye color.
Prevalence of Hazel Eyes by Ethnicity
The incidence of hazel eyes varies between different ethnic groups. Here is a breakdown of the prevalence of hazel eyes by broad geographical ancestry:
– European – Around 10-15% of Europeans have hazel eyes, making it more common than in most other ancestry groups. Hazel eyes are especially prevalent in north, eastern, and central Europe.
– Middle Eastern/North African – Estimated at 5-10% prevalence.
– Sub-Saharan African – Less than 5% of Sub-Saharan Africans have hazel eyes. Brown eyes are by far the most common.
– East Asian – Only 1-2% of East Asians have hazel eyes. Brown eyes prevail in East Asian populations.
– South Asian – Around 5% or less have hazel eyes, with brown being the vast majority.
– Native American/Indigenous peoples – Hazel eyes are very rare, with almost all having brown eyes.
– Oceania – Aboriginal Australians have over 90% brown eye prevalence. Hazel eyes are somewhat more common among Maori and other Pacific Islanders at 10-20% prevalence.
So in summary, hazel eyes are most common among those of European descent and are considerably rarer among Africans, East Asians, Native Americans and Aboriginal populations. Prevalence ranges between 5-15% for most non-European groups.
Changes in Hazel Eye Color Over Time
One key feature of hazel eyes is that the exact shade often changes from childhood into adulthood. Newborns with hazel eyes tend to have a greyish-blue eye color that progressively darkens over the first few years of life as melanin content increases.
By age 3-5, the adult eye color is usually established. Hazel eyes at this young age tend to be more solid brown/amber. As children get older, the melanin concentrates around the edges of the iris, revealing more green shades that give hazel eyes their signature multicolored look.
The melanin content and distribution in the iris continues to change over time. Hazel eyes often appear more brown/gold in youth, shifting to a greener shade from the teens into middle age. Later in life, hazel eyes may darken again. These changes are subtle, but can result in noticeably different hazel eye shades over a lifetime.
Rarity of Hazel Eyes Compared to Other Rare Eye Colors
Now that we’ve looked at the genetics and prevalence of hazel eyes, how rare are they compared to other uncommon eye colors like green, amber and grey eyes?
Here is how hazel eyes compare:
– Green eyes – about as common as hazel eyes at around 2-3% prevalence globally. Slightly rarer than hazel eyes among Europeans, but more common in some Asian and African countries. Overall rarity is comparable to hazel eyes.
– Amber/Gold eyes – much rarer than hazel, found in only around 1% of people globally. The least common eye color.
– Grey eyes – also very rare, estimated at less than 1% prevalence. Mostly found in Northern and Eastern Europe.
– Red/Violet eyes – extremely rare. Thought to occur in less than 0.1% of people. Caused by albinism or genetic mutations like Waardenburg syndrome. Often considered mythical or legendary.
So hazel eyes are significantly more common than the very rare amber, grey and red/violet eye colors. They are roughly equal in rarity to green eyes globally. The only eye colors more common than hazel are shades of brown and blue.
Conclusion
In summary:
– Hazel eyes arise from a genetic mix of variants associated with brown and green eye colors, producing an iris with a multi-colored appearance.
– Approximately 5-8% of people worldwide have hazel eyes, making hazel eyes relatively rare compared to the most prevalent brown eye color.
– Hazel eyes are most common in people of European ancestry, with 10-15% prevalence. Other ethnicities have hazel eye incidences of 1-10% typically.
– Hazel eyes are about equally as common as green eyes globally. They are significantly rarer than shades of brown and blue eyes, but more prevalent than very rare colors like amber, grey or red eyes.
So while considered special and uncommon, hazel eyes are not exceptionally rare, occurring in around 1 in every 10-20 people of European heritage and 1 in 20-100 people of non-European ethnicities. Their rarity compared to brown eyes makes hazel eyes stand out as a unique and appealing eye color.