Evolution and REPRODUCTION
We are, fundamentally and emotionally, animals. As animals, we are governed by emotions first.
Fundamentally, we still have to compete to breed due to a male and female required for sexual reproduction. It all comes down to survival and reproduction.
It’s not survival of the fittest to survive; it’s survival of the fittest to reproduce. Having a propensity to Alzheimer’s in your 70’s won’t do much because that is generally past your reproductive potential. When you’re 16-20, your status and how you stand among your “tribe” can tremendously impact your survival and reproduction.
Any factor outside your age of reproductive potential or one that doesn’t affect your ability to pass on genes won’t affect your survival and reproduction.