system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Will everyone on Earth eventually have the same/similar skin hair colour?
gpt
Different skin colors came about in the first place because of natural selection.

People who lived in deserts and other places with continuous, harsh sun gained extra protection against the excessive UV that hit their skin by growing extra melanin.

People who lived in climates where the sun shined less than the optimal amount required for their skin to create vitamin D with sunlight, lost pigment in an attempt to compensate.

Neither of these pressures have gone away. There's still way too much UV hitting the skin of people who live in the Sahara desert, and way too little hitting the skin of people who live in Siberia.

Unless the entire earth is somehow drastically changed to eliminate all differences in sunlight, there will always be differences in skin color.