Why are white people white?

Question

WHY ARE WHITE PEOPLE WHITE AND BLACK BLACK?

Answer 1

Hi Richard K.,

(not that I suspect you'll read this, but perhaps others may) --

The above two responses indicate what makes, and why, skin pigments exist. But they don't address why it might be advantageous to have LESS pigment. That's b/c humans need to convert vitamin D2 into D3 in their skin, to have it exert maximal beneficial effects in the body (and it does have many effects!). That requires direct sunlight, and it's believed that dwellers in northern regions, where sunlight is less direct, hence weaker and much less effective for the D2->D3 thing, lost pigmentation in order to have enough D3 made to stay healthy.

There are other erroneous theories of why white skin (or people) might excel. No evidence for such theories, however.

-- Cheers, -- Mr. d.

Answer 2

Melanin is a protein made by cells called melanocytes. These cells are found in the lower layers of the skin’s epidermis (stratum spinosum). Melanin is secreted by melanocytes and taken up by the keratinocytes that make up the majority of the epidermis (the outer layer of the skin). This next part is super cool: the melanin is not just in any old place in the keratinocyte. It is specifically located on the “sunny side” of the nucleus. In other words, the melanin is placed between the nucleus of the keratinocyte and sunlight, kind of like a molecular umbrella! Can you think why this might be important…? Sunlight contains ultraviolet radiation. Ultraviolet radiation can cause mutations in DNA. DNA is contained in the nucleus of the cell. So melanin is placed between the DNA and the sun in order to absorb the ultraviolet radiation and protect the DNA from damage. DNA mutations do not always cause cancer, but cancer is the result of some DNA mutations. This is why darker skinned people have a lower incidence of skin cancer. Darker skinned people make more melanin (as Kamran explained).

Answer 3

The protein melanin is what is responsible for giving pigment to a person's skin. This protein is synthesized by melanocytes which themselves are derived from neural crest cells. The quantity of melanin being synthesized can and does impact the color of one's skin. Exposure to sunlight increases the creation of melanin by melanocytes.

However, there are limits to this effect. What really makes a white person skin white is the type of melanin that is synthesized by their melanocytes.

This is why no matter how long a white person stands in the sun they will never get the skin pigment of a black/dark skin person.

Answer 4

The color of the skin is  dependent upon the level of a pigment called melanin in your skin.  The more you have, the darker you are.  Melanin is a protective pigment against the sun, thus, people living closer to the equator tend to have more melanin as compared to people living in the northern or southern hemispheres.

Answer 5

Varying amounts of melanin in the skin

Answer 6

Skin pigmentation in humans is a delicate balance of different levels of melanin pigmentation. People living near the equator are exposed to higher levels of UV rays, so they need higher levels of melanin to absorb the extra rays.

But if UV rays are so harmful, then why doesn't everyone have lots of melanin (or, more specifically, the darker melanin variety called eumelanin)? UV rays are also needed for the synthesis of Vitamin D3, which is critical for the body to regulate calcium levels. 7-dehydrocholesterol is converted into inactive Vitamin D3 by UV rays in the skin. Vitamin D3 is then activated in the liver, before acting on the kidneys and intestines to help those organs absorb/reabsorb calcium.

However, UV rays also damage folate, which is a metabolite needed for DNA synthesis and energy production. Therefore, individuals must balance the ability to synthesize Vitamin D3 with the downside of folate destruction or DNA damage. This evolutionary balance results in people at equatorial latitudes having darker, more melanin-rich skin to protect against stronger UV rays, while people at latitudes closer to the poles have whiter, less melanin-rich skin.

Answer 7

The colour of skin is dependent upon the level of a pigment called Melanin. And thus protein is made by cells called melanocyte.

Answer 8

The number of melanosomes are the same in human skin. In the white skin the melanosomes which are melanin or pigment making cells don't make as much melanin as in dark skin.. The production of melanin is controlled by the melanocyte stimulating hormone and ACTH.