"I am gonna go in a different direction here I will say finding out what actually causes sickness. For much of humanity this argument had fierce advocates of miasma to why did you make God give you leprosy? The black plague and a pope surrounding himself with candles which attracted fleas and allowed his survival is the greatest doesn’t matter it worked ever."
Humans can’t be used as an example. Unlike any other species, we go very far out of our way to make sure the weak and feeble-minded survive.