How am I changing the subject when it is Darwin himself who attempts to give a biological explanation for man's moral faculties in chapters four and five of The Descent of Man?
In this sense what makes for a sympathetic society, a society that will be stronger and longer-lasting than those around it, is the foundation of morality.
As per Hume, It is invalid to derive "ought" from "is." No ethical principle can be legitimately founded on a fact of nature, so biological principles cannot be translated into moral imperatives. My point is that Darwin's insistence on the continuity of man and animals vitiates any foundation or justification for his own transcendent ethical pronouncements, e.g., "happiness is an essential part of the general good." in chapter 21 of the book. His premises are self-defeating.
As Thomas Huxley put it,
The thief and the murderer follow nature just as much as the philanthropist. Cosmic evolution may teach us how the good and the evil tendencies of man may have come about; but, in itself, it is incompetent to furnish any better reason why what we call good is preferable to what we call evil than we had before.A foundation devoid of ethical content is no foundation at all.
Cordially,
A foundation devoid of ethical content is no foundation at all.
And ethical is what works best with man's interaction as a society. As I said, religious ethics and morality are simply what man had already figured out codified into religion, so religious ethics and morality have no extra standing above anything Darwin would say.