Final answer:
The hypothesis in question is that darker skin evolved as a protective adaptation against UV radiation, reducing the risk of sunburn and skin cancer. Melanin in darker skin absorbs and dissipates harmful UV rays more effectively, providing a natural defense mechanism in regions with strong sunlight.
Step-by-step explanation:
The hypothesis that suggests individuals with dark skin color have less risk of sunburn and skin cancer from ultraviolet radiation is based on the protective role of melanin, a pigment found in the skin. People with more melanin have darker skin tones which provide a higher degree of protection against the damaging effects of UV radiation. This adaptation is thought to have evolved to confer a survival advantage in regions with high UV radiation exposure.
Sunburn is a direct result of UV-B and UV-C radiation causing damage to the outer layer of the skin. Over time, repeated exposure to UV radiation can increase the risk of skin cancer. However, individuals with darker skin have more melanin, which absorbs and dissipates UV radiation more effectively than lighter skin, thus reducing the likelihood of sunburn and by extension, the risk of developing skin cancer.
The physical geography of human evolution played a significant role, with darker skin being an evolutionary adaptation in sunny regions to mitigate the harmful effects of UV radiation, while lighter skin emerged in areas with less sunlight to facilitate the production of vitamin D. The variations in skin pigmentation we see today are a result of both chance and natural selection, shaped by the differing amounts of UV radiation humans were exposed to as they migrated across the globe.