“What you get from dance and singing on its own is a sense of belonging. It happens very quickly. What happens, I suspect, is that it can trigger very easily trance states,” Dunbar said. He theorizes that these spiritual experiences matter much more than dance and song alone. “Once you’ve triggered that, you’re in, I think, a different ballgame. It ramps up massively. That’s what’s triggered. There’s something there.”
From the viewpoint of increasing fitness, that is, passing on one’s genes, being able to make war or to repel aggression required larger and unified tribes. A need to bind people together in larger aggregates then drove the evolution of traits that promoted group loyalty. Religion, especially early religions, served not only to bring people together but to give them assurance that they and their families would survive, either in this life or in one to come. A belief that one’s God(s) had chosen one’s own tribe gave members the strength to face overwhelming odds, with the result that they sometimes turned back less dedicated opponents. Moreover, religion and its constant demands facilitated the identification of potential free riders, strengthening group solidarity.
The emergence of high-moralizing gods is an important example of this. In small-scale hunter-gatherer religions, the gods are typically whimsical. They're amoral. They're not concerned with your sexual behavior or your social behavior. Often you'll make bargains with them, but as we begin to move to the religions in more complex societies, we find that the gods are increasingly moralizing. They're concerned about exactly the kinds of things that are going to be a problem for running a large-scale society, like how you treat other members of your religious group or your ethnic group. Experiments run at UBC and elsewhere have shown that when you remind atheists, it doesn't matter, but if you remind believers of their god, believers cheat less, and they're more pro social or fair in exchange tasks, and the kinds of exchange tasks that they're more pro social in are the ones with anonymous others, or strangers.