God may or may not exist, but His followers certainly do. Nearly every civilization worships some variety of supernatural power, which suggests that humans are hard-wired to believe in something that, by definition, is not of this world. But why? Evolutionarily speaking, how could belief in something in the absence of physical evidence have aided the survival of early Homo sapiens? Evolutionary biologists Stephen Jay Gould and Richard Lewontin of Harvard University proposed that religious thinking is a side effect of tendencies that more concretely help humans to thrive.

Perhaps the most primitive is our “agency detector,” the ability to infer the presence of others. If the grass rustles in the distance, our first instinct is that someone or something may be lurking. This propensity has obvious evolutionary advantages: if we are right, we have just alerted ourselves to a nearby predator.