I agree with one of the first responses saying that humans are amoral and that notions of good and evil are contrived from societal notions and zeitgeist.
As for some of the other posts, I feel like altruism comes from empathy and empathy comes from being glorified pack animals. In other words, what's good for another person is good for the pack, albeit indirectly. So humans are inherently selfish, but the term needs to be broadened a little bit. It's our individual selves that we care about, and altruism fits within that. (One could also assert on a less macroscopic level that altruism makes a person feel good and they do it for that selfish reason.)
I think that humans as a species function differently than the other animal species on the planet. We have far fewer physical resources for survival than any other species I can think of right now, so we compensate with forming groups (and that whole higher intelligence thing). Give it a hundred thousand years and you give rise to these uber-societies, where we are by far the dominant species on the planet's surface. There's no "good" or "bad" about it - it's just evolution.
Looking at some people's medical record, I wonder men's construction is inherently bad. Especially considering the failure rate being 100% - eventual death being a question of when, not if.
We have to have 100% failure rate because that's how life and darwinism works. If you didn't die then your gene combination wouldn't be removed from the pool, which is theoretically refining itself and becoming more "fit" over the centuries. (Sorta like how Duncan Idaho got his butt kicked by a girl in God Emperor of Dune). So I'd say our construction is inherently "good", since it benefits the species.
As far as people acting individually selfish, it's just so that they can reproduce. Obviously you'll still have 80 year olds who are terrified of death and would sacrifice a teenager over themselves, but that's just how we're built. I don't think we're meant to be AS concerned with the greater good as we are for our own good - the greater good kind of takes care of itself. It's a heirarchy of cause and effect. I think we have this in common with all life forms on the planet. So the question I'm stuck on is why life? Why any of it? Sagan says we exist in order for the cosmos to know itself, and a bunch of other goobers say its so that we can know God.
Sorry for tangenting the OP and then tangenting my tangent. It's hard for me to not break everything back down to evolution when it comes to the "why's" of society.