AP Biology class blog for discussing current research in Biology

Tag: Human skin cells

The Biology of Skin Color

It’s a hot summer day and you are relaxing by the pool. Ever wonder why your skin gets darker or tanner when doing so? It’s because of melanin! 

Melanin is a skin pigment that can be found in humans, animals, and most organisms. It is responsible for making hair, skin, and eyes appear darker. Melanin exists in two forms: eumelanin and pheomelanin. Eumelanin is black or brown pigment and pheomelanin is red or yellow pigment in one’s skin tone. 

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Different Skin Colors

When you are exposed to the sun, more melanin is produced. “In human skin, melanin pigments are synthesized in organelles called melanosomes that are found in specialized cells called melanocytes in the skin epidermis.” In order for melanocytes to produce melanin, a receptor protein called MC1R, found in the melanocyte cell membrane must be activated by melanocyte-stimulating hormone (MSH) which is secreted by the pituitary gland in response to exposure from UV light. Once MC1R is activated, it triggers the production of release of cAMP and as we learned in class, this triggers a cell signaling pathway ending with the release of eumelanin, making our skin appear darker. 

A short additional fact is that melanin protects us from skin cancer. Melanin can absorb the UV rays and block them from reaching and damaging the DNA within one’s melanocytes. In this case, melanin acts as “a protective agent in the skin” joining your first line of defense to protect you against pathogens or in this case to protect you against the damaging UV rays. There are three types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. 

A person’s skin color depends on the amount and type of melanin (eumelanin or pheomelanin) present in one’s skin. Genetically speaking, “people with naturally darkly pigmented skin have melanosomes that are large and filled with eumelanin” ( As discussed above, there is a huge biological importance of melanin; without it, humans wouldn’t have a protective skin barrier against the UV rays emitted by the earth, but throughout history the importance of melanin has been placed to the side due to the idea of race or more specially racial superiority based on ones skin tone being introduced into the conversation. 

In short, while there is a biological basis of skin color, there is no biological basis or scientific explanation of race. Although it has been attempted, by Samuel Morton in the 1800s when he compared the brain sizes of the five racial groups or by Dr. Menegele during WWII when he measured facial features of the Jewish people, it is challenging to use science to support the concept of race. In fact, there are more differences within the “determined” races (African, European, Asian, Oceania, Native American) than between them! No specific amount of melanin, or any trademark alleles for that matter, specify a race. It is important to look at and understand science and evolution- looking at where people come from and why they have that skin color that they do based on melanin and weather conditions around them. It is important to take into account how we have evolved into unique humans, even though 99.6 – 99.8% of our genetic material is identical. It is important to educate ourselves about why we are the way we are and how evolution has impacted that, not how groups of people throughout history have tried to give an racist explanation for it.  

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Skin Colors Found Around the World



Photo Credit: Ashabot

Many people say animal testing is definitely reasonable because apparently the life of a human outweighs the life of an animal. Yes, we have made much progress in finding new cures that work on being tested, but over 100,000 people die from newly prescribed medicine that cured the disease in animals. Animals have different genetic codes than humans and therefore just because the cure of a disease works on an animal does not mean that it will 100% work on humans.

Animals are being tortured during testing. They are being forced fed chemicals and are left in pain while they are locked away and are restrained. Over half of the millions animals being tested either die during the testing or are killed after tests. The Animal Welfare Act is suppose to make sure scientists treat animals being tested with good care. They must provide adequate housing, sanitation, treatment, nutrition, and veterinary care. But the Animal Welfare Act only protects animals before and after testing. So scientists don’t have to follow it during testing!

So why test on animals if its the new cures that work on animals don’t work on humans? Why put the animals through pain and suffering if the cures might not always work? I still believe that it is important for scientists to keep on developing new cures, but there are other alternatives to finding these cures other than animal testing such as using human skin cells or human skin  leftover from surgical procedures. These are ways that can still develop new cures and there is probably other methods to use to test scientists new theories and cures. So do you support animal testing?

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