It’s a chicken-egg thing. I say morals were developed by societies as a way to work together and become stable. Care for others in a society being necessary to the strength of that society was even written about by Darwin. He didn’t apply genetic natural selection to humans because he knew it, a.k.a., eugenics, wouldn’t work due to our social nature. Over time these basic rules of interaction were codified into various religions as morals, commandments from God.
“He didn’t apply genetic natural selection to humans because he knew it, a.k.a., eugenics, wouldn’t work due to our social nature.”
Firstly, he didn’t know about genes. He prefigured them, in a way, since his variations in inheritability had to be passed on through some medium or other. But not really.
Secondly, he did so apply natural selection to humans. He assumed, following Malthus, that the same forces shaping the animal kingdom held for humans. Which made him, and to an extent all his followers (especially the stupid, stupid sociobiologists), ignorant of human nature. Not to say evolution isn’t one of the greatest scientific theories of all time. It is. It just doesn’t apply to humans, or certain other species with which humans mess.