One interesting point that anthropologist Jared Diamond makes in "The Third Chimpanzee" is that chimps and dolphins are about as moral (and immoral) as humans are in most comparable situations, and then gives some specific examples.
A good many more socially adept animals show traits we think of as purely human, and one of those is they can display compassion, loyalty and honesty, and some animals for whom it is biologically advantageous even practice monogamy without ever hearing one hellfire sermon on the evils of promiscuity.
The morality of bonobo chimps is sexually more promiscuous than ours, but they have us beat all to hell in the peaceful department. Mostly because they've learned to use sex as a social tool even better than we have. They literally would rather make love than war...something that so far only a few hippies have managed to put into practice among humans.
But it is interesting that the factors that influence unacceptable or violent social behavior are the same for most mammals as they are for us...lack of food and other resources, overcrowding, sexual competition, plain old boredom, social anxiety, the "stranger" factor, psychotic individuals, etc.