As the graph I included above indicates, the incidence of melanoma in white men is much higher than in other races and genders. Based on this week’s materials, there are a few possible explanations for this trend. One major contributing factor is of course genetics. Another possible explanation is lifestyle choice.
Primarily, I would like to address the genetics involved especially focusing on the evolution of modern skin pigmentation differences in different races. Melanin is the pigment which is chiefly responsible for skin color, and protects from the sun by blocking ultraviolet rays . It is important, however to have some sunlight to synthesize vitamin D. Too much of this UV light however, can destroy folic acid, another important nutrient in the body. Thus, the amount of melanin in the skin must evolve to balance the amount of vitamin D produced and the amount of folic acid that is preserved. It is easy to see then, that in areas that receive more direct sunlight vitamin D needs can be met easily, so more melanin is present to protect folic acid. In areas where exposure to direct sunlight is reduced, melanin is less abundant in the skin because folic acid is plentiful, and vitamin D needs must be met. There is also dietary intake to be accounted for, but that is not important for this explanation.
So, evolutionarily, melanin present in skin was the result of geographic location. Today, where people can travel all over the world, the skin does not immediately adapt to level of sunlight. Thus, people with less melanin exposed to equal amounts of UV rays would be expected to have a greater incidence of melanoma.
Finally, there is also a disparity between men and women of the same race. Lifestyle choice could be associated with this correlation. Perhaps men are being exposed to the sun more often, or are less apt to use protective measures such as sun screen when they are exposed.
U.S. Centers for Disease Control and Prevention. 2013. Skin Cancer Rates By Race and Ethnicity. Last modified August 13. http://www.cdc.gov/cancer/skin/statistics/race.htm
U.S. National Institutes of Health. 2012. Cancer Trends Progress Report. Last modified June 20. http://progressreport.cancer.gov/doc_detail.asp?pid=1&did=2007&chid=71&coid=711&mid=#trends
National Museum of Natural History. 2014. Skin Modern Human Diversity- Skin Color. Last modified July 10. http://humanorigins.si.edu/evidence/genetics/skin-color/modern-human-diversity-skin-color