one thing that is typical of our scientistic moment, as in the late nineteenth century, is the idea that we can derive morality or moral values from evolution. now, i am afraid not, and i will briefly state the overwhelming problems.
(1) the classical is/ought problem: evolution cannot account for normative force or moral claims. so let's say it was counter-evolutionary to take your stuff. is that a reason not to take your stuff? you might have many good arguments that it's wrong to take your stuff, but the idea that i am swimming against the tide of evolution might be met with a mere shrug. what if it turned out that some forms of violence or crime were adaptive? would that show that they were right? also evolution makes use of counter-adaptive behavior as much as adaptive behavior. acting counter-adaptationally is necessary to the progress of the species, and i and my offspring will pay the price if in fact i am so acting.
(2) the basic inference has to be from actuality to etiology: arguments from evolution start by presuming that we are what evolution made us. so look: staring squarely at the data, we ought to speculate that both what we would think of as good behavior and bad have been selected for, insofar as we so stubbornly display both. insofar as evolution has selected us, it has, obvioously, selected both cooperation and competition, good and evil, happiness and pain, and so on. it appears, like the rest of nature, to be morally indifferent. if it was really selecting against theft or individualist philosophy or something it should have done better than it has so far in weeding out thieves and individualists.
in short if you want ethics without god you are going to have to find it elsewhere.