How have the historic levels of melanin in human populations changed due to migration? (1 point)
Migration patterns have played a significant role in shaping the distribution of melanin levels in human populations. As humans migrated to different regions with varying levels of sunlight exposure, natural selection favored individuals with adaptations that allowed them to survive and thrive in those environments.
For instance, as early humans migrated out of Africa into regions with less intense sunlight, such as Europe and Asia, there was a decrease in melanin levels in their skin, hair, and eyes. This likely occurred as individuals with less melanin were better able to produce vitamin D in areas with lower UV radiation levels. Lighter skin allows for increased vitamin D synthesis, which is essential for bone health and overall immune function.
Conversely, as humans migrated to regions with stronger sunlight, such as closer to the equator, melanin levels increased to provide protection against harmful UV radiation. Darker skin has a higher concentration of melanin, which absorbs UV radiation and prevents DNA damage and skin cancer.
Overall, migration and the variation in sunlight exposure have contributed to the evolution of diverse melanin levels in human populations, as an adaptive response to different environmental conditions.