Does morality have natural origins?

I think the argument for the development of morality is similar to the development of the eye. We see it implemented in nature at gradual levels of development and conclude that it has natural origins. In particular, the use of in/out group thought, which aids in individual survival. More specifically, an organism will form sub-divisions within its environment to cooperate, which will benefit the group (In human development, progressions such as Family, Tribe, National, and International communities create synergy). For example, Piranhas don't attack each other in a feeding frenzy, but they would be happy to attack something that isn't in their group. There are numerous examples of different species of animals demonstrating morality in some form or another. I'm not entirely sure what the religious explanation for morality is, but if it doesn't incorporate animal morality, then I don't find it very credible.