Religion is a product of oral tradition, taboo, and superstition. These features of human behaviour played a valuable role in protecting humans from dangers we did not individually understand. Fires, lightning, floods, drought, poisons, diseases (especially sexually transmitted diseases) underlie much of the religious beliefs and other cultural superstitions you can see even today.

A favourite of mine is the processing of cassava aka manioc by indigenous Amazonian tribes. Their cultural practice involves a long, multi-stage cooking and washing process which removes the cyanide that is naturally present in the root. The amazing thing is that the cyanide levels are high enough to cause chronic poisoning but low enough to not present any short term symptoms besides a bitter taste. However, taking shortcuts with the process leads to a reduction in the bitterness without actually removing enough of the cyanide to prevent chronic poisoning.

This means that this cultural practice maintains a complicated process that can’t be immediately supported by the available evidence (bitterness) but nevertheless provides a strong protective effect against chronic poisoning. In the absence of modern chemistry, this complex practice could only have developed through a long process of cultural evolution selecting against tribes who suffer from the chronic cyanide poisoning.