There is a species of cave fish who over jillions of years stopped developing eyes because they live in a place with no light. You can still see where the eyes used to be.

Mankind went from grunting and dragging women around to inventing chili cheese flavored corn chips and a full featured computer that fits in your pocket.

Evolution is a fucking miracle.

The answer to your question: some people have evolved far slower than others, and are still morons. :)