It starts off:
"Where do moral rules come from? From reason, some philosophers say. From God, say believers. Seldom considered is a source now being advocated by some biologists, that of evolution.
At first glance, natural selection and the survival of the fittest may seem to reward only the most selfish values. But for animals that live in groups, selfishness must be strictly curbed or there will be no advantage to social living. Could the behaviors evolved by social animals to make societies work be the foundation from which human morality evolved?"
Read the entire article here: Is 'Do Unto Others' Written Into Our Genes?