Ever wonder why people actually have different eye colors? Honestly, the question is not so easy to answer, because research results are still not so long ago. So why do we have different eye colors?
If you believe the research, there is the color blue as the eyes only for 6,000 – 10,000 years, originally namely all our ancestors had brown eyes. The blue eyes seem to be caused by a mutation, so that a single man suddenly had blue eyes. From the descendants and all of today’s blue-eyed people, the researchers have found.
The blue-eyed people are so dependent on the brown-eyed and that will of course be inherited through the genes. Now, however, still remains the question of the other color combinations such as green or turquoise.
The players are some other factors, besides the evolution of the role, are in fact the iris pigments, which are stained by the enzyme known as melanin. People with little melanin have a very light eye color. The more melanin deposited in the iris, the darker are the eyes. The different colors occur naturally in the inheritance, because the colors are mixed by the father and mother.
On the inheritance of eye color at least three different genes are involved, their exact functions are still not completely understood. What color eyes have the child produces depends on the combination of genes passed from both parents to the child.
Published by the GC Davenport and CB Davenport in 1907 one-gene model, the inheritance of eye color explained most simply, but describes the complex reality of inheritance only inadequate, as we know today. According to this model there is only one gene that determines eye color (brown or blue). This gene is diploid, ie before so in two copies. The Davenport model there are two versions for each copy (alleles), one for blue eyes (ie, no capacity for melanin production) and one allele for brown eyes (ie the ability of melanin production). For example, the father has two brown eye color alleles, the mother two blue eye color alleles that each child one brown and one blue allele is obtained.
The Davenport model is the eye color, which the man later, depends on which allele is dominant and which is recessive. This applies, brown eyes are dominant, while blue eyes are recessive. That is, in the example above, the child would have brown eyes. In another generation, but both genes are shared equally. If the above child’s father, whose wife also brown eyes (with one blue and one brown allele), so at least 25%, the probability that a blue-eyed child is created, which has two blue genes and can pass any brown genes. To another 75% the child will have brown eyes. However, the probability that one of the alleles are blue, but amount to 50%.
Davenport described the model is now considered obsolete. In reality, the inheritance of eye color is brown / green / blue checked / gray by more than one gene. It is the function of genes bey2 (abbreviation for. Brown eye 2) and gey (green eye) as assured. Bey2 exist for the gene alleles for brown and blue eyes, for the gey gene are alleles for green and blue eyes. This dominance is the following sequence: From top to bottom decreases the dominance to recessiveness.