human skin color likely represents a compromise between the need to blend into the environment and the need to absorb sunlight for heat. the need to block uv radiation that causes cancer and the need to absorb sunlight for heat. the need to block uv radiation that destroys folate and the need to absorb sunlight for heat. the need to block uv radiation that causes cancer and the need to blend into the environment. the need to block uv radiation that destroys folate and the need to synthesize vitamin d.
