In my opinion, snare&racket summed it up pretty nicely, but I'd like to add a few thoughts:
Humans are not the only species with altruistic behavior. As others have stated, it has more to do with survival than with concepts of good and evil. What differentiates us from most if not all other species, is that we have the capaciy to analyze our actions and rationalize them. This means that we can take our natural reactions, and choose to obey them or fight them, depending on what we personally feel is the right (or most beneficial) thing to do.
Most social animals are altruistic within their flock, hive or herd. We are pretty unique in that we can choose our group arbitrarily, not only based on family, but on virtual constructs like religion or what bike we ride. The western world's reaction to the Thailand tsunami a few years ago shows the processes very clearly: people pretty much ignored all other victims of this catastrophe than the Thai population. For a few weeks, they actually pretty much ignored most of the problems in the world except those of a small part of the Thai population. In essence, they associated with this relatively small group of people as if they were part of the same group, and distanced themselves from other victims of bad things that happened concurrently in other parts of the world.
Richard Dawkins put it nicely in his book The Magic of Reality. It's really a children's book, but it's an enjoyable read. He summed the suffering problem up with the words "bad things happen because things happen". In essence, the universe isn't out to get us - that would count as evil. But sometimes things happen that we might be tempted to take personally, while they're simply the result of random processes or statistical chance. It's important to see the difference between, say, a person choosing to rob others under gunpoint, and someone developing pancreatic cancer for no other reason than that they've lived long enough for the odds to stack up against them. The second example simply can't be attributed to evil, even if you'd be hard pressed to find someone who thinks it's fair.