Men and women

Ursula K Leguin is most famous as an author of fantasy and science fiction, although she's also done some interesting academic work.  In 2010 she wrote this.  It seems fairly satisfactory to me, and the point that greater aggression and competitive instincts need to be more thoroughly subsumed in mutual respect 'in-group' seems right.  This is the thing with group selection arguments for morality.  There is almost a 'conservation of good behavior' so that it should never be too much; to construct in-group altruism, you establish the need for out-group genocide. (You can't, after all, allow interlopers inside an altruistic space to take advantage.  This is rather like the need for Hell in Christianity.  You can't say 'Yes' to humanity without saying no to mans inhumanity, or sin.)