Definition
The religion-as-byproduct hypothesis proposes that religious belief is not itself a trait favored by natural selection, but rather an incidental side-effect of mental capacities that evolved for other, practical reasons. On this view, religion rides on the back of dispositions that were useful in their own right.
A standard analogy is the moth that flies into a candle flame. The moth is not adapted to immolate itself; it is adapted to navigate by distant light sources such as the moon, and a nearby flame hijacks that otherwise sensible behavior. Religion, the argument runs, may similarly exploit ordinary cognitive equipment.
Why it matters
How it works
Dawkins draws on the idea that children are primed to absorb instruction from adults without testing it, a tendency that protects them from danger but also makes them receptive to whatever beliefs their culture supplies. Combined with a readiness to attribute purpose and agency to events, this leaves humans prone to religious ideas as an unintended consequence.