Evolution has meant that our prefrontal lobes are too small, our adrenal glands are too big, and our reproductive organs apparently designed by committee; a recipe which, alone or in combination, is very certain to lead to some unhappiness and disorder.
Evolution is, as well as smarter than we are, infinitely more callous and cruel, and also capricious.
I'm here as a product of process of evolution, which doesn't make very many exceptions. And which rates life relatively cheaply.