Why are there so many blue eyed people?

[Heraclitus]

My estimate would be about 200 million (about a third of Russians/Ukranians/Belorussians, a fifth of Americans, Half of Scandinavians + All the rest)


My question is considering that blue eyes are a recesive trait, how come there are so many? Also how exactly does such a gene spread if it has no selective advantage from a common ancestor?

[DanS]

A fifth of all Americans? Not a chance.

[Dinner]

Easily a fifth and I'm one of them.

[Heraclitus]

A fifth of all Americans? Not a chance.

From wikipedia:

Blue eyes have become increasingly rare among American children with only 1 out of every 6 – 16.6 percent which is 49.8 million out of 300 million (22.4% of white Americans) of the total United States population having blue eyes.[25][26] The plunge in the past few decades has taken place at a remarkable rate.


Sorry forgot about non-white Americans, but It seems my gut feeling wasn't too off.

As a kid I was under the impression that Slovenians wheren't very blue eyed. In my city I only had 3 schoolmates with blue eyes in primary school. In High School about 30% of people seemed to have blue eyes. Now in college I'd estimate about 50-60% of my classemates have them.



My point is that using your personal experience as a guide may be misleading when talking about demographics.

[Dr Strangelove]

My estimate would be about 200 million (about a third of Russians/Ukranians/Belorussians, a fifth of Americans, Half of Scandinavians + All the rest)


My question is considering that blue eyes are a recesive trait, how come there are so many? Also how exactly does such a gene spread if it has no selective advantage from a common ancestor?

How did the male peacock get its tail? It serves no selective advantage except that femal peacocks dig it. Maybe blonde hair and blue eyes got selected because young people with those traits stood out amongst their brown hair brown eyed sexual competitors and got shagged more.

The other thing to consider is that blue eyes go along with a pale complexion. A blue eye is blue simpy because it has less melanin pigment in the iris than a brown eye. Presumably the factors which selected for light skin made the likelihood of some people having blue eyes more likely. In areas of the world where there is less sunlight having less pigment in the skin is thought to increse the amount of 1,25 vitamin D produced because one of the final steps of 1,25 vitamin D synthesis requires sunlight. As Nordic, Scythian and Celtic peoples evolved lighter complexions the amount of pigment (melanin) in their irises also decreased. In some it decreased to the point that when combined with red light reflected from the highly vascular retina the very light golden-brown iris actually came to look blue.

[Asher]

Not only do I have blue eyes, they're extremely blue.

[Combat Ingrid]

As a kid I was under the impression that Slovenians wheren't very blue eyed. In my city I only had 3 schoolmates with blue eyes in primary school. In High School about 30% of people seemed to have blue eyes. Now in college I'd estimate about 50-60% of my classemates have them.

Interesting correlation

[FrostyBoy]

Can you explain green eyes? I have green eyes.

[onodera]

22.4% is an okay percentage for a recessive trait. It doesn't negatively affect your chances to survive and get some poon (on the contrary, even), so it isn't bred out by natural selection. Also, don't forget that billions of people have brown/black eyes. Blue eyes are not that common at all.

[SlowwHand]

I have blue eyes.What makes me special is that most blue-eyed people have streaks of yellow in the blue. My streaks are green.

[Joseph]

Blue for me.

[zakubandit]

I have blue eyes, my father, mother, both brothers have blue eyes. My wife has brown eyes, my son has blue eyes. Blue is in the family and thats pretty much it. Mine are a deep blue, my son has a cobalt blue, my little brother has an ice blue. We got slammin eyes.

[Krill]

My eyes are ****ed up, but most of the time they are grey.

[Heraclitus]

22.4% is an okay percentage for a recessive trait. It doesn't negatively affect your chances to survive and get some poon (on the contrary, even), so it isn't bred out by natural selection. Also, don't forget that billions of people have brown/black eyes. Blue eyes are not that common at all.

Of course blue eye's aren't common, but far more people have them that they should. And in the US blue eyes are being bread out. So my question is since even the most blue eyed countries don't go over 60% is why there are so many blue eyed people in absence of a founder effect.

From wikipedia:

A 2002 study found the prevalence of blue eye color among Caucasians in the United States to be 33.8 percent for those born from 1936 through 1951 compared with 57.4 percent for those born from 1899 through 1905.

[Heraclitus]

I have blue eyes, my father, mother, both brothers have blue eyes. My wife has brown eyes, my son has blue eyes. Blue is in the family and thats pretty much it. Mine are a deep blue, my son has a cobalt blue, my little brother has an ice blue. We got slammin eyes.

If I remember my genetics right at least one of her parents must have been carrying a recesive blue eyed gene.

I think it goes:
Blue eyed parents > ~98% blue eyed children
One parent has blue eyes the other brown> child has either blue or brown eyes
Both parents brown> if they are both carrying the recessive gene blue is quite possible. Otherwise brown.