I found this blog post quite informative from a psychological perspective.
http://evoandproud.blogspot.co.uk/2011/01/religiosity-and-origins-of-civilization.html (http://evoandproud.blogspot.co.uk/2011/01/religiosity-and-origins-of-civilization.html)
Quote from: AnthropologistsAtkinson and Whitehouse argue that human societies seem to cluster into two modes of religiosity:
1. An "imagistic" mode associated with hunter-gatherers. Religiosity is focused on non-routine events that evoke an intense state of mental arousal (initiation, ordeals, bodily mutilation, etc).
2. A "doctrinal" mode associated with agricultural societies. Religiosity is more routine and is focused on frequently repeated teachings and rituals that generally evoke a less intense state of mental arousal.
Among hunter-gatherers, religiosity is meant to be traumatic. The aim is to create a vivid experience with long-lasting effects, such as an emotional bond that will keep men loyal to each other for hunting or war.
In agricultural societies, religiosity supports tasks that occur more often and more regularly