Why has religion been selected for in modern human cultures? – What role or func

Why has religion been selected for in modern human cultures?
– What role or function can/ does religion play in modern human societies?
– Incorporate a discussion on the earliest evidence for religion/ spiritual belief systems, their structural characteristics and what they were concerned with.
– What anthropological and biological mechanisms in our earliest ancestors likely gave rise to the earliest religion/ spiritual belief system (recall dreaming and trance in hunter gatherer groups such as aborigines; Also recall Skinner’s superstitious pigeons)?