Melinine Mutations, and Why we Have Diversity in Eyes and Skin

Skin, it is an important covering for your body. The whole job of our somatic cells is to protect our skin from damage to DNA by UV rays. Contained in our genetic structure are genes with a determinate amount of melanin. It determines the amount of pigmentation expressed in our phenotype. This has caused the separation of many nations.

The question here is why? Looking into our ancestral ties, going back to the chimp-like ancestor, we were likely all very dark pigmented. The ones who carry the largest mutation of inactive genes are those of us with light skin, and blue eyes. For every eye color, and skin color, and hair color that is less than black to dark brown is an inheritance of genes that do not function. This is likely the reason that people who marry a blue eyed person have more brown eyed offspring. Because the DNA will use the functioning genes and pass over the non functional one. When it comes to blue eyes, the lighter they are the more genes that are non functional for melanin production. This is also the reason for the variation in the colors. It is not just one gene that is non functional, but can be many, as we have seen in Albinos. The more genes that do not function the less melanin we produce. This can be highly damaging to DNA due to UV rays effecting the structure. We do produce keratin to protect our skin as well but in high areas of UV exposure it is more likely that light skin will suffer damage.

It is quite a trivial thing to think about when it comes to the value of a person, yet even in modern days we see people using it to characterize differences in humans who are all a part of the same species. Race is a social construct based on nothing more the the facial structure of a person and the amount of melanin genes being expressed in their phenotype. The changes we see in body structure and facial structure are based on area and environmental variation. We can only speculate at the ancestors who left Africa, but the divergence led to skin lacking much production of melanin to skin producing high amounts of melanin. If you look at areas and distribution of melanin production per area, you can see that in Europe where there is not as much intense UV radiation people had less melanin production. Where the mutation of the genes began no one knows, but it became so common people normalized this. While in Africa people continued to survive based on having enough pigmentation to protect the skin. In Asia and North America people survived by having a medium amount of pigment.

So who has the bragging rights here? That would go to those with darker skin and eyes. Since they carry functional genes that may help protect them as global warming takes hold. Since the heat will continue to cause stress on the ozone layer, there will be more UV penetration. People with light skin may suffer higher damage to skin. While those producing the melanin will have a better chance of protecting their DNA. Those of us with blue eyes can suffer retinal damage to high exposure to light. While those with brown eyes have protection. Blue eyes actually function better in low light and adapt quicker to the dark. But brown to black eyes can tolerate intense amounts of sun. So with the climate changing we may see more instances of light skinned and eyes becoming damaged. Or environmental stresses may produce more people who have functional melanin producing genes.

What we take for granted to separate us may be the one thing that saves us. The fact is melanin is vital for people to have. Otherwise we would be producing massive amounts of cancer cells. The top layer of our epidermis is dead and used to protect vital living cells, but this does not prevent UV exposure to living cells, or their DNA. So melanin is the best protection we have. The dark pigmentation prevents the UV light from causing the structural damage to the DNA. We should all be glad to have our melanin, its function is vital, and we need it to survive getting all forms of skin cancer. So love your melanin.

Comments

  1. Kevin SaldanhaApril 30, 2012 at 5:06 PM

    We had Dr. Esteban Parra speak at our recent Cafe Scientifique in Mississauga on this topic. Here is an article on his work
    http://www.racesci.org/racescinow/genetics,race,and%20ancestry/3.html

    ReplyDelete
    Replies
    1. Rachel JApril 30, 2012 at 7:18 PM

      Wow, thank you so much Kevin. I am reading, very awesome.

      Delete

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