It makes sense that the animals most evolutionarily close to us would exhibit early manifestations of higher social behavior. In this case, scientists have observed that some primates are surprisingly sensitive to others' problems. For example, chimpanzees can't swim. Despite this, some chimpanzees have drowned in zoo moats trying to save others from drowning.
More evidence: Scientists set up an experiment where rhesus monkeys could pull a chain to get food. If they pulled the chain, however it would shock one of the monkey's companions. The result? They starve themselves for several days.
Behaviorists say that human morality grew out of this primate sociality, with two extra levels of sophistication: humans have a much more rigorous enforcement of moral codes with rewards, punishment and reputation building. We also have a degree of judgment and reason, something that other animals haven't developed.