Posted on 01/30/2008 2:10:37 PM PST by decimon
New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today. What is the genetic mutation
“Originally, we all had brown eyes”, said Professor Eiberg from the Department of Cellular and Molecular Medicine. “But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a “switch”, which literally “turned off” the ability to produce brown eyes”. The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. The “switch”, which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris – effectively “diluting” brown eyes to blue. The switch’s effect on OCA2 is very specific therefore. If the OCA2 gene had been completely destroyed or turned off, human beings would be without melanin in their hair, eyes or skin colour – a condition known as albinism. Limited genetic variation
Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes. “From this we can conclude that all blue-eyed individuals are linked to the same ancestor,” says Professor Eiberg. “They have all inherited the same switch at exactly the same spot in their DNA.” Brown-eyed individuals, by contrast, have considerable individual variation in the area of their DNA that controls melanin production.
Professor Eiberg and his team examined mitochondrial DNA and compared the eye colour of blue-eyed individuals in countries as diverse as Jordan, Denmark and Turkey. His findings are the latest in a decade of genetic research, which began in 1996, when Professor Eiberg first implicated the OCA2 gene as being responsible for eye colour. Nature shuffles our genes
The mutation of brown eyes to blue represents neither a positive nor a negative mutation. It is one of several mutations such as hair colour, baldness, freckles and beauty spots, which neither increases nor reduces a human’s chance of survival. As Professor Eiberg says, “it simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so.”
I knew I was a mutant mutt.
How mutant are you? Got pix?
Normandy was founded by Rolf the Granger who was exiled from Norway for murder. He went into exile with some young tough guys who decided that Northern France was ripe for conquest because it was populated by Frenchmen. In the spirit of Gallic collaboration/capitulation the King agreed to recognize the Northmen’s claim to Normandy if they recognized the sovereignty of the French King.
A small landholder with too many sons Tancred de Haughtville, sent them down to Italy to become soldiers of fortune. Seeing that they were the only real warriors in southern Italy at the time they decided to take it over (actually meeting the Pope’s army in battle and defeating it) as well as undertaking a conquest of Islamic Sicily and an attempt to conquer Byzantium (at the time probably the largest and most powerful empire in the world).
William the Bastard of Normandy became William the Conqueror when he defeating the English and instituted Norman rule of England.
When the First Crusade came, Bohemund and Tancred, two Norman Princes, joined the fight and claimed the Crusader Kingdom of Antioch (one of the largest metropolises of the ancient world).
Bohemund also fought to take over Byzantium, and like his father came within one battle of winning, ironically at the same location!
Thus a small landholder in Normandy, Tancred de Haughtville’s children became the Norman Rulers of Normandy, England, Southern Italy, Sicily, and Antioch.
Sometimes I do! Could that be the reason?
I'll second that....
Where do we meet?
Hey, maybe we hit on something here! LOL.
They really got around, didn’t they?
LOL........Wow !
If both your parents had blue eyes and you had brown eyes, the answer would be no.
Actuually, the eye thing is a little more complicated. My husband had brilliant clear blue eyes, mine are hazel. Both our boys have very dark brown eyes. My husband was 1/16th American Indian. I have Mongolian Tartar from the German Slavic side of my ancestry. I believe that the Oriental Brown eye is recessive to most of the possible European based colors, but that in our case my Asian genes were able to express themselves against my husbands pure blue color as that is the most recessive of all the eye colors. In addition, the one son has very dark hair and a swarthy cast to his skin color. The other son has high cheekbones and almond eyes. At birth he had a faint epicanthic fold to his eyelids which has since disappeared. Personal note: I took a semester of Genetics and Heredity in college.
If the husband has one gene for blue and one gene for brown, and the wife has one gene for blue and one gene for some other color, statistically there is a one in four chance that a child will have blue eyes. Three out of nine is close enough since statistics and reality are not identical.
With two green eyed parents, they would each have a blue eyed gene, however, the green is much lighter than brown, and would contribute much less melanin, so perhaps some shade of blue might include a green genetic input. My husband had very clear light blue eyes. Our grandson has fairly dark blue eyes. I feel certain my husband was a pure recessive for blue, but I’ll bet our grandson has a little bit of melanin in his eye color. Don’t be suspecting infidelity based on your two cases.
LOL No infidelity here. I’m Mom. I think I would know.
But really hubby and I have grandparents/great-grandparents with blue eyes. Genetic expression is fascinating. :-)
I have pondered that myself. My vision is exceptional in conditions that other claim are "pitch black" (I will spare you the stories). The only problem with that is that I am painfully and literally almost entirely snow blinded after short exposure to sunny winter conditions.
As much as I like and want to support the theory, we would have been forced to have been nocturnal creatures capable of completing life sustaining tasks as well as our diurnal relatives or have invented slit goggles at about the same time as the mutation.
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