Answer:
variation in skin color.
Explanation:
The human skin color is determined genetically depending on the amount of melanin. However pigmentation can occur as a results of exposure to uv rays that causes induced pigmentation.
The sun emits two types of ultra violet rays which can reach can reach the skin namely the uva and uvb. Both type of rays can damage the skin if unprotected. Due to this there was evolution against the damaging rays. More melanin that provides a natural sunscreen to the people leaving in the tropic environment.
