Guided Response: Review several of your peers posts that contain a biological trait different than the trait you chose, and compare findings. Respond to at least two of your peers and provide recommendations to extend their thinking. Each response should be at least 50 words in length.

BOOKER

A person's skin color can vary depending on where they live because of UV radiation. The environment plays a key role in natural selection. According to the video, people with the darkest skin pigments live towards the equator, and those with lighter skin pigments live toward the north and south poles (Jablonski, 2009).

UVB is very important because it promotes vitamin D in the skin which is needed for strong bones and overall health. People that live in the equatorial region get more UV radiation than those living in the poles. Therefore, people living in the equator have a darker skin color and more melanin.

During human evolution, once people moved out from Africa, there was some UVA and a lot less UVB radiation because it was spread throughout the environment. Once people went to live in the Northern Hemisphere, they lost their pigmentation because of lack of UVB radiation and natural selection coincided with people as they evolved with lightly pigmented skin (Jablonski, 2009). When a person moves from Africa to Sweden, they have less vitamin D in their skin.

A vitamin D deficiency can cause many problems for people's health such as; weakness in their bones, decline in the immune system, loss of immune function, mood changes, as well as mental health problems (Jablonski, 2009). People that do not experience much sun can take a vitamin D pill to help with the deficiency.

I found an interesting article that stated people's metabolism has adapted over the years. "Another area of recent evolution is how our metabolism has changed to allow us to digest some things that we could not in the past. The most obvious example of this is lactose, the sugar in milk.

Some 10,000 years ago, before humans started farming, no one could digest this beyond a few years of age. But today, the rate of lactose tolerance in different parts of the world is a clue to the different histories of farming across the globe.

While 99% of Irish people are lactose tolerant, in South East Asia, where there is very little tradition of dairy farming, the figure is less than 5%" (Bootle, 2011, para. 9). Once people started farming cattle, their digestive system became used to drinking milk. Those not exposed to dairy milk cannot digest it. This is a trait that became passed down to many generations showing the evolution of natural selection in human biology.

References

Bootle, O. (2011). Are humans still evolving by Darwin's natural selection? BBC News.

Jablonski, N. (2009). Nina Jablonski- Breaking the illusion of skin color [Video file].

Ms.Blums

Our skin pigmentation is the evidence of evolution, natural selection and our ancestors adaptation to their environment. Our skin color is the most conspicuous and marked evidence of this adaptation. As early humans moved away from the equatorial zones on the earth, their skin color pigmentation grew lighter. This relationship between darker skin and being closer to the equator is that UVB rays are high. The body produces melanin which is a natural sunscreen and protects the skin from UVB rays.

As our ancestors moved away from equatorial areas their skin adsorbed less UVB rays or no UVB rays at all. When there was less UVB rays the skin pigmentation lightened and that caused a sinister problem. The UVB rays manufactured vitamin D which is essential to our bodies. So if the person moved from Malawi, Africa to Stockholm, Sweden their family would eventually lose pigmentation and vital vitamin D.

Just as if you get too much sun you can use sunscreen to protect your skin. If you get too little sun, and thus little vitamin D, you would need to take vitamin D supplements. Why you ask? Vitamin D is very important to bone health the immune system, and even mental health. Vitamin D deficiency could cause the fact you are getting sick more often because you need it for your immune system. Also, you can feel more tired; or in particular in a woman's case cause loss of bone mass.

So you see, something so seemingly insignificant as skin color causes a lot of health issues. It is a symptom of our evolution and keeping up on ways to protect ourselves from lack of sun and too much sun are important issues.