I appreciate the thought. I still have some doubt. One is cultural. The Shakers held a belief not to procreate. They made themselves extinct in the same environment others thrived. In the same way, Europe may become a mid-east/African majority simply because white people refuse to procreate at the same high rate. Both live in the same environment. I see a cultural aspect to evolution which favors or punishes the tribe for its cultural beliefs.
How that works over long time periods is a mystery to me.
When you get to cultural effects on evolution, you just add a new level of complexity. The behavior of individuals most certainly affects evolution, not just in humans but in many species.
Another complication are the traits which confer both advantages and disadvantages. For example, many female birds like to mate with brightly colored male birds. But brightly colored male birds cannot easily hide from predators. So there are two opposing forces affecting male bird color.