What is the selective pressure for darker skin color?

Selective pressure for darker skin color is the result of adaptation to different environments and climates. Dark skin is more beneficial in areas with high levels of UV radiation, such as near the equator, as it provides protection against sunburn, skin cancer, and folate degradation.

In regions with lower levels of UV radiation, individuals with lighter skin are able to absorb more sunlight and synthesize more vitamin D, which is crucial for bone health and immune function. Therefore, there is a selection for lighter skin in these areas.

The variation in skin color among human populations is a result of the balance between these selective pressures and other factors such as genetic drift and gene flow. Over time, genetic variations have led to the diverse range of skin colors we see in different populations around the world today.