>>12718777>country has more sun>animals have more melanin for protection from harmful uv rays>country has less sun>animals have less melanin for better vitamin d productionIt's not exactly rocket science. It's not just humans either, look at arctic animals which are often white.
Basically, everything works out well for everyone so long as we all stay within our natural boundaries.
So we don't move to fucking Africa to get cancer, and you don't move here to get a vitamin D deficiency. Everybody happy.