The main problem with claiming the behavior of certain animals is evidence for the natural development of human morality is that those behaviors are only considered moral and immoral by humans, not the animals themselves. An ape or dolphin or dog may in fact exhibit something like altruism or tenderness – but neither apes nor dolphins nor dogs distinguish between those acts and acts which we would consider immoral, like killing over food, or forced copulation, or theft. To an animal they are just behaviors, the way such animals act in certain circumstances. Human morality however is a set of rules which specifically distinguishes between behaviors – and we are the only organisms which identify and articulate those sorts of rules. There is nothing occurring in the animal kingdom that would indicate this occurs as a matter of natural development of species.