I said, "Skin cancer does exert a very strong selective pressure on reproductive success. Many theories have been proposed for the evolution of dark skin pigmentation – and a new paper revives one of the oldest: that skin cancer was a more potent selective … The graph in Figure 2 summarizes the age at which people are diagnosed with melanoma, the most serious form of skin cancer. Clark M (2010) Skin assessment in dark pigmented skin: a challenge in pressure ulcer prevention.Nursing Times; 106: 30, early online publication. Abstract. I'm having trouble answering some of these questions. Q. In dark skinned populations the MC1R locus is extremely conserved, suggesting powerful selective constraints which prevent sequence variation. On what evidence did she base this hypothesis? Human skin color ranges from the darkest brown to the lightest hues. The graph in Figure 2 summarizes the age at which people are diagnosed with melanoma, the most serious form of skin cancer. Overall, human skin color is a highly variable and complex trait as a consequence of strong selection pressure and is controlled by multiple genetic loci (summarized in Table 1). Darker skin is more prevalent in high-UV areas. Why does protection from skin cancer not explain the strong selective pressure for dark skin in high UV ares. Dr. Nina Jablonski proposed a hypothesis to explain the selective pressure for darker skin in these environments. While evidence is still being collected, most scientists agree that the natural selection for the lighter eye colors is linked to the relaxation of selection for the darker skin tones. As human ancestors began to migrate to various places around the world, the pressure for selection of dark skin color was not as intense. In this model the dark skin of humans naturally arose because women who were darker skinned carried more normal fetuses to term than those who were light skinned. On what evidence did she base this hypothesis? Ancestral populations near the equator were selected for dark skin, while those living in higher northern latitudes were selected for lighter skin. Why does protection from skin cancer not explain the strong selective pressure for dark skin in high UV ares. Skin assessment is a vital element in the prevention of pressure ulcers, and many recommendations for skin assessment depend on visual and tactile cues to identify changes in skin appearance. Pigmentation, (skin color), in humans has evolved under selection pressure from the duration and intensity of sunlight. One of them asked, "how strong a selective pressure do you expect skin cancer (UV-induced mutations) to exert on reproductive success?" Q. Nina Jablonski proposed a hypothesis to explain the selective pressure for darker skin in these environments. Pressure on reproductive success the strong selective pressure for dark skin in UV., `` skin cancer not explain the selective pressure for dark skin in environments... 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