Everyone in this world with blue eyes is descended from one European who lived about 8,000 to 10,000 years ago.For the first time, he developed a specific mutation which ensured that around 150 million people (2.2% of the world’s population) are now running blue irises.
Why this is so special?Because all the people on Earth originally had brown eyes. However, the tint of the brown eyes could still differ from the gene OCA2 which regulated the amount of brown pigment.
But recently there is a mutation of a similar gene called HERC2 discovered where the cause of the blue eyes lies.This turns off the OCA2 gene, which causes brown pigment. It is believed that this first occurred when one began to emigrate from Africa to Europe, which means that every person with blue eyes descended from one European.
The fact that every person with blue eyes has the same mutation is a clear proof of this theory, although the identity of that particular person still remains a mystery.The first blue colored eyes were discovered at a 7000 years old skeleton, which was discovered in northern Spain. Of course, the eyes were long-lived, but genetic research revealed that they would have been blue.
That of blond hair I will also throw at it for the enthusiast.
Japanese research quite recently found evidence that the special mutation of the hair dye MC1R that caused the blond color could not have been older than about 11,000 years.In Europe There is a remarkable genetic variation of the gene with seven different basic types.
In May 2012, a study was published in Science that demonstrates that a mutation of TYRP1 causes the blond color in inhabitants of the Solomon Islands.The frequency is between 5 and 10 percent. Earlier it was assumed that the hair colour blond in Oceania was the result of European explorers, traders and others who visited there in the previous centuries. The isanders themselves gave some alternative explanations for the blond hair, such as sun exposure, or a diet rich in fish.
It has now been demonstrated that it is a mutation that does not occur in Europe, it is clear that the blond hair colour has emerged independently from each other at least two places.
If you haven’t read enough.Here the explanation for green eyes.
Green eyes are considered special, especially as they occur relatively little.Worldwide there is a wide variety of spread of a green eye color. In Iceland, even 80% of the population has blue or green eyes! Also in the Netherlands relatively many people have a green eye colour. Other countries where relatively many children with green eyes are born are Iran, Pakistan, Central Asia, Spain, Germany and Brazil. Globalisation is increasing the variation in the population. This may result in an increase in the number of people with green eyes. However, scientists cannot give any certainty about this.
How to create green eye color
The eye color is determined by the color of the iris.The iris consists of two layers. The posterior part is a thin layer, with a thickness of 2 cell layers. This section is called the epithelium, which contains black pigment particles. The front part is the most important part for the eye color. This part is called the stroma in which melanin is located. Melanin is a brown pigment, which determines apart from the color of the eyes also the color of the hair and of the skin. In addition, the density of the cells and the amount of black pigment in the posterior part of the iris plays a role in the final eye color.
Green eyes have only small amounts of melanin in the stroma (people with blue eyes have no melanin in their iris).Incoming light is mixed with the small amount of brown melanin, which reflects it as a green color. This effect is called the Rayleigh effect and works according to the same principle as allowing us to see the color of the sky as blue.
Determination of the eye color
When a baby is born, the eyes usually have a blunder color because they still produce little to no melanin.From an age of about six months, a child gets melanin in the iris which gives it a certain eye color. The greater this concentration is, the darker the color of the iris is. The final eye color is only fixed around an age of 3 to 4 years.
Many studies divided the eye color into 3 kinds of colors: blue (blue and grey), green and brown.This format was found to be very simple. In 2011, Mackey divided the eye colour into nine categories so that more distinction can be made in eye color. Some people have blue or green eyes with a brown ring around the pupil. This makes the layout even more complicated.
Sometimes a spontaneous mutation occurs that causes a trait that is not detrimental to survival and reproduction.And then there is also no natural selection against the gene that causes this trait. This gene, and therefore the associated trait, can be passively spread by the population.
When the further useless feature is found attractive by sexual partners, this property can also become an advantage for such an individual because it can attract a greater number and or more desirable partners to continue Plants than individuals without this trait.In this case, the gene will also be actively spread by the population through sexual selection.
Blue (and green, gray, light brown, etc) Eyes is probably an example of such a mutation.
Evolution has no reason.Nature leaves everything to chance.
Mutations in animal and plant species are arbitrary.Some make the likelihood of survival bigger, others are not.
Those mutations that increase the likelihood of survival are passed on to the next generations.
The mutations that reduce the probability of survival are normally dying.
‘ Blue eyes ‘ have no reason whatsoever.The chances of survival do not increase, but they also do not make the species weaker. So that may well ‘ grow ‘ in the gene pool without being favoured or punished.
‘ Focused Evolution ‘ is a fable, an attempt to harmonize religion and science.
So depending on how you define gene, there will also be a gene for the attractive finding of blue eyes.It inherits itself intertwined with the property of blue eyes itself by hereditary input of the attracted partner (and thus keeps the question together with the offer in progress). Thus, sexual selection on a certain scale will have randomly-resembling outliers but must have been a vehicle for an active advantage in a different context (between such suckers it can be observed on some scale again selection or- Depending on how you look at it-you will find useful selection on a single scale. Brown, blue and green may have had a functional advantage over white, red and black eyes but it is negligible from the first three compared to each other. The same molecular mutation will also be able to be part of other genes as for hair color.
Passive/active, useful/harmless, (or not) sexual selection are therefore entirely related to the context of observation.For example, mutations can M.I. simultaneously make the cell replication mechanism less error-prone and make someone more or less attractive. Cell replication plays a role immediately after conception. If that lower error sensitivity was at issue only in circumstances of 100,000 years ago, we will not see any more of that.