What factors caused the correlation between the reduction in skin pigmentation in humans and migration of human populations away from the equator
1. Ultraviolet (UV) radiation: Areas closer to the equator receive more intense UV radiation from the sun. Higher levels of UV radiation can be harmful to the skin, leading to sunburn, skin cancer, and other negative health effects. In order to protect themselves from these effects, populations living near the equator may have developed darker skin pigmentation, which acts as a natural sunscreen.
2. Vitamin D production: UV radiation is also essential for the production of vitamin D in the skin. In regions with lower levels of UV radiation, such as areas further away from the equator, individuals may have developed lighter skin pigmentation to allow for more efficient production of vitamin D.
3. Adaptation to environment: As human populations migrated away from the equator to regions with different climates and levels of UV radiation, natural selection favored individuals with lighter skin pigmentation in order to adapt to these new environments. Lighter skin allows for better absorption of UV radiation needed for vitamin D production in regions with lower levels of sunlight.
4. Genetic drift: Over time, genetic mutations and gene flow between different populations can also play a role in the evolution of skin pigmentation. As human populations migrated and interbred with each other, genetic diversity increased, leading to variations in skin pigmentation among different populations.
Overall, a combination of factors such as UV radiation, vitamin D production, adaptation to new environments, and genetic drift contributed to the correlation between the reduction in skin pigmentation in humans and the migration of human populations away from the equator.