Recently I read a magazine article that said human babies are born to be sociable and helpful. Babies as young as 18 months will try to help adults pick up dropped items, for example. From the age of 12 months they will point to objects a researcher has pretended to have lost. Because this behavior is consistent across cultures, some scientists propose that humans are born with a cooperative nature.
By the time most children are 3 years old, however, they may want to be helpful to some people but not others. They're also catching on to social "norms" and may be a bit bossy about everybody following rules.
There's a long-standing debate about whether humans are intrinsically violent. I've heard it said that some of the recent violence within Buddhism, such as Buddhists attacking Muslims in Burma, just shows us that people are inherently violent and there's not much you can do about it. But babies show us that, maybe, that's not true.
It makes sense that, as a species, we'd be wired to be helpful to others. We are social creatures and need each other to survive. But evolution might also have left us with a tendency to form tribal loyalties and to conform to group norms, whatever those are. That can get us into trouble if we aren't careful.
On the other hand, I don't see how being greedy, bigoted or violent might have given earlier hominids an evolutionary advantage over other species. If our ancestors had all been murderous thugs, I don't think any of us would be here now.
The Buddha taught that our capacity to harm ourselves and others ultimately comes from our false belief in a permanent self that must be protected and provided for at all costs. This is the ignorance of the Three Poisons. To me, this makes much more sense than just believing we're just bad because we're made that way.