Religion is a cultural universal. Humans in every known society practice some type of religion. So it’s tempting to believe that is part of evolved human nature, that humans are evolutionarily designed to be religious. Well, the answer is yes and no.

In my last post, I discussed how Haselton and Nettle’s Error Theory explains intersexual , why men always overinfer women’s sexual interest in them. One of the great features of Error Management Theory is that it can explain a wide variety of phenomena. It is a truly general theory.

Imagine you are our ancestor living on the African savanna 100,000 years ago, and you encounter some ambiguous situation. For example, you heard some rustling noises nearby at night. Or you were walking in the forest, and a large fruit falling from a tree branch hits you on the head. What’s going on?

In an ambiguous situation like this, you can either attribute the phenomenon to impersonal, inanimate, and unintentional forces (for example, wind blowing gently to make the rustling noises among the bushes and leaves, or a mature fruit falling by the force of gravity and hitting you on the head purely by accident) or to personal, animate, and intentional forces (for example, a predator hiding in the dark and getting ready to attack you, or an enemy hiding in the tree branches and throwing fruits at your head). The question is, which is it?

Once again, Error Management Theory suggests that, in your inference, you can make a “Type I” error of false positive or “Type II” error of false negative, and these two types of error carry vastly different consequences and costs. The cost of a false-positive error is that you become paranoid. You are always looking around and behind your back for predators and enemies that don’t exist. The cost of a false-negative error is that you are dead, being killed by a predator or an enemy when you least expect them. Obviously, it’s better to be paranoid than dead, so evolution should have designed a mind that overinfers personal, animate, and intentional forces even when none exist.

Different theorists call this innate human tendency to commit false-positive errors rather than false-negative errors (and as a consequence be a bit paranoid) “animistic ” or “the agency-detector mechanism.” These theorists argue that the evolutionary origins of religious beliefs in forces may have come from such an innate cognitive bias to commit false-positive errors rather than false-negative errors, and thus overinfer personal, intentional, and animate forces behind otherwise perfectly natural phenomena.

You see a bush on fire. It could have been caused by an impersonal, inanimate, and unintentional force (lightning striking the bush and setting it on fire), or it could have been caused by a personal, animate, and intentional force (God trying to communicate with you). The “animistic bias” or “agency-detector mechanism” predisposes you to opt for the latter explanation rather than the former. It predisposes you to see the hands of God at work behind natural, physical phenomena whose exact causes are unknown.

In this view, religiosity (the human capacity for belief in supernatural beings) is not an evolved tendency per se; after all, religion in itself is not adaptive. It is instead a byproduct of animistic bias or the agency-detector mechanism, the tendency to be paranoid, which is adaptive because it can save your life. Humans did not evolve to be religious; they evolved to be paranoid. And humans are religious because they are paranoid.

Some readers may recognize this argument as a variant of “Pascal’s wager.” The seventeenth-century French philosopher Blaise Pascal (1623-1662) argued that given that one cannot know for sure if God exists, it is nonetheless rational to believe in God. If one does not believe in God when He indeed exists (false-negative error), one must spend eternity in hell and damnation, whereas if one believes in God when he actually does not exist (false-positive error), one only wastes a minimal amount of time and effort spent on religious services. The cost of committing the false-negative error is much greater than the cost of committing the false-positive error. Hence one should rationally believe in God.

However, Pascal cannot explain why men always come on to women, whereas Haselton and Nettle can. The intriguing suggestion here is that we may believe in God and the supernatural forces for the same reasons that men overinfer women’s sexual interest in them and make unwelcome passes at them all the time. Both religious beliefs and sexual miscommunication between the sexes may be consequences of the human brain designed for efficient error management, to minimize the total costs (rather than the total numbers) of errors. We may believe in God for the same reason that women have to keep slapping Beavis and Butt-head to set them straight.