The Colour of your Eyes

March 26, 2014

What determines your eye colour??
There are a lot of different eye colours in humans but some are rarer than others. Just look around you and take a good look at peoples eye colour. There is a high chance you will notice a lot of people with brown eyes. Brown eyes are by far the most common in humans. In some countries, the brown eyes are the only colour there is.
In other countries however, you will find a lot of diversity. Green, blue, hazel, grey and even violet eyes do exist as well.

Green eyes in the Middle East


Brown is the most common eye colour
In the US only 1 out of 6 people have a light (blue) eye colour. The brown eye colour  in the US is the most prevalent. No surprise, because brown is also the dominant colour. In other countries, especially in northern Europe, brown is less common. Estonia for example is a very light eyed country with almost 98% having blue eyes !.
Africa is very brown
The further you go to the south, the more chance there is that you will find a person with brown eyes. In southern Europe for instance, there is on average an  80% chance you will find a brown eyed person. Lighter eyes are also in southern Europe (Spain, Italy, Portugal and Greece) less common. Further south, going to Africa, light eyes have almost disappeared.
Light eyes in Scandinavia
Scandinavians tend to have a very light appearance. Light eyes are definitely the standard in these northern countries. Sweden, Norway and Denmark all have high percentages of light eyed people. Also Finland and Iceland are extremely light with almost 90% of them having light eyes (green, grey and blue). Other ”northern” countries like The Netherlands, Scotland and Germany have light eyed peoples too. In The Netherlands approximately 80% of the inhabitants have green or blue eyes. Germany (especially the northern part of the country) follows with almost 70% having lighter eye colours.
Green eyes are rare
Within the ”light” eyed population, the green eyes are outnumbered by the blue eyes. Green eyes are dominant over the blue eye colour but there are only very few people that carry the genes responsible for green eyes. Only 1-2% of the entire human population have green eyes.

Green eyes can look very different. They can be very dark, almost brown. Sometimes they are very light: almost neon. It all depends on the amount and type of melanin inside the iris. If you have a lot of melanin, your eyes look darker and if you have only a tiny bit, your eyes tend to look very light (bright).

Light green eyes are most common in Iceland, The Netherlands, Scotland, Ireland, Estonia and Scandinavia. Dark green eyes can be found all over Europe, the US and even in Pakistan.

Light green eyes
Green eyes and red hair
Scientists suspect there is a relation between red hair and  green eyes. It looks like there is a high correlation between those two human traits. Having  red hair colour is also very unique (and recessive). Only 1 – 2 % of the entire human population have natural red hair. Of course, not only red hair coexists with green eyes-also blondes and darker hair colours can have green eyes (or the other way around).

Green eyes and gender
Normally, you would expect a 50/50 gender variation between the eye colours (blue, brown), but scientists have found a positive correlation between being a woman and having the green eye colour. Why green eyes are more found in women is still unknown and it is not certain a gender differentiation actually exists. The findings could be biased somehow.

red hair, green eyes and being male: the odds are very low


Hazel eyes are Green eyes?
Some people confuse hazel eyes with green eyes. Hazel eyes are also very rare but are different than green eyes. First of all, hazel eyes have more melanin. They look more brownish and are overall a bit darker, sometimes with a golden tint. People with hazel eyes often notice a considerable change in their eye colour, especially when a lot of light reflect on their eyes. Secondly, some green eyes have a lot of yellow pigment in them. Hazel eyes share this yellow pigmentation hence the confusion.

Where do green eyes come from?
Green eyes can be found anywhere but you will find them most of the time in Europe. Some people believe green eyes came to existence due to a mixture of blue and brown eyes. This idea became popular because a lot of green eyes can be found in areas where brown and blue eyes came together. When we look at the map, the highest percentage of green eyes can be found in Scotland. Ireland also has (relative) a lot of green eyed inhabitants.

Green eyes have lipochrome. This lipochrome (also known as feomelanin) is a yellowish pigment. People with green eyes and especially those with amber coloured eyes have a lot of this yellow lipochrome inside their irises. Those with blue, brown or grey eyes usually don’t have any lipochrome. When you have a lot of lipochrome inside your iris, you might have  amber eye colour. When you only have a small portion of this yellow pigment, your eyes might look a bit more green/blue-ish.

The combination of the yellow pigment and low amount of melanin gives rise to light green eyes. When you have a moderate amount of melanin but also lipochrome, your eyes probably look darker green. When you only have a low amount of melanin (and no lipochrome), your eyes look blue.

Heterochromia Iridum
Some people have a truly unique thing going on with their eyes: they have more than one colour! When one eye has a different colour than the other; it is called heterochromia iridum. When only a small portion of the iris has a different colour, it is called: partial heterochromia.