Essay Example on Human skin pigmentation as an adaptation to UV Radiation

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The article Human skin pigmentation as an adaptation to UV radiation mentions that humans have different skin colour based on the region where they live or their ancestors lived because the traits are passed from generation To explain further people who lived near to the equator region where the ultraviolet radiation is higher have darkly pigmented skin and people in the Northern zones usually have light pigmented skin colour This was necessary because in the northern zones people need to absorb more UV for Vitamin D production whereas people in the equatorial zones need to reflect some of the UV radiation since this region is rich on UV so as to inhibit folate damage Jablonski N Nina G 2000 Moreover they suggest that people who have less body hair tend to have darkly pigmented skin because they need to lose body heat when exposed to hot environmental conditions and skin get caught directly by the sun Cooling by evaporation of eccrine sweat is impeded by thick body hair Also there are some problems involved with the migrants For instance when people who have darkly pigmented skin from equatorial zones move to latitudinal zones like

Canada where sufficient UV only in late spring summer and early fall months from around 10 am 2 pm they get less UV which in turn pushes them to Vitamin D deficiency Current Epidemiological Evidence showed that 42 4 of African American females have low levels of Vit D vs only 4 2 of white American females So they are supposed to take some Vitamin D supplements or try to get it through their diet Approximately 90 of this vitamin in people is normally synthesized in their skin and the kidneys from a cholesterol like a precursor chemical with the help of ultraviolet radiation The remaining 10 comes from foods such as egg yolks and fatty fish Interestingly our bodies convert Vitamin D into two simple forms The second form commonly known to as vitamin D3 is required for the intestines to absorb phosphorus and calcium from food for bone growth and maintenance Besides that calcium also plays an vital role for adults to maintain normal heart action blood clotting and a stable nervous system New evidence report done by Daniel Niel suggests that vitamin D may aid in preventing wide range of cancers including those of the colon and breasts Niel D 2013 Furthermore the actual reason behind Skin colour is due to the presence of a pigment called melanin which is controlled by at least 6 genes Melanin is present in both light and dark complexioned people However two forms are produced namely pheomelanin which is red to yellow in colour and eumelanin which is dark brown to black Pheomelanin is produced mostly in people with light complexioned skin whereas those with dark coloured skin mostly produce eumelanin In addition the number and size of melanin particles is different for different individuals National Cancer Institute 2015

These two variables are more important in determining skin colour than the percentages of the different kinds of melanin In lighter skin colour is also affected by red cells in blood flowing close to the skin To a lesser extent the colour is affected by the presence of fat beneath the skin and carotene a reddish orange pigment in the skin Even hair colour is also due to the presence of melanin Over exposure to UV may lead to melanoma which is a type of cancer produced by the cells called melanocytes It typically occurs in the skin National Cancer Institute 2015 In the United States approximately 54 000 people get this aggressive type of skin cancer every year and nearly 8 000 of them die due to it Those at highest risk are European Americans They have 10 times higher risk than African Americans National Cancer Institute 2015 Moreover another disease caused by overexposure to UV would be anemia which is caused by the breakdown of folate in the body Folate is derived from the folic acid one of the B vitamins in our food

 Pregnant women who have folate deficiency are at a higher risk of having miscarriages and babies with defects in their neutral tube Because folate is essential for DNA replication in dividing cells its absence can have an effect on many body processes especially the production of sperm cells The ultimate reason behind the ability to produce melanin was selected for in our early human ancestors because it helped preserve the body's supply of folate in addition to reducing the chances of developing skin cancer Jablonski N 2009 To sum it up it's really essential to ensure that you get enough Vitamin D as it is important for healthy bones Especially if you live in the northern countries make sure to get the required amount of vitamin D through diets or supplements since UV is available only for a short period of time during a year Therefore Skin colour is a product of our evolutionary history related to UV radiation and the need for particular micronutrients folate and vitamin D that affect reproductive success from lecture slides


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