Vampire bats are social creatures who share their food with starving roost mates. This behavior evolved because it was beneficial for survival and so was selected for by evolution and natural selection. When we share food with starving people we call it the moral thing to do since we are a social species and the behavior is beneficial for survival. Beneficial = moral, detrimental = immoral.
I still don't understand what the object of your appeal is to, to actually determine what makes for beneficial and detrimental. I can guess, as I already have, but rather hear it from you.
Until then, I would observe that killing is beneficial (relatively speaking) as many creatures rely on killing other creatures for food. Though also detrimental as being killed for food is not so good for species survival if its members are being picked off one by one.
Side note: I routinely wish "natural selection" was referenced more accurately as "non man-made selection" for all man made actions/results are, without exception, naturally occurring (relative to physical existence, of course).