Religious practice is costly in terms of material sacrifice (at least one's prayer time), emotional expenditure (inciting fears and hopes), and cogni… - Scott Atran

Roughly, religion is a community's costly and hard-to-fake commitment to a counterfactual and counterintuitive world of supernatural agents who master people's existential anxieties, such as death and deception.

In the course of life, all such systems (i.e., the different evolutionary ridges) are somewhat functionally interdependent, as are components within each system (i.e., the different programs, schema, modules) . Nevertheless, each system and system component has a somewhat distinct evolutionary history and time line. There is no single origin of religion, nor any necessary and sufficient set of functions that religion serves. Rather, there is a family of evolutionary-compatible functions that all societies more or less realize but that no one society need realize in full.

One such evolutionary system, or ridge, encompasses panhuman emotional faculties, or affective "programs." These include the basic, or primary, emotions that Darwin first identified: surprise, fear, anger, joy, sadness, disgust, and perhaps contempt. Certain reactions characteristic of the neurophysiology of surprise and fear are already evident in reptiles, and the other primary emotions are at least apparent in monkeys and apes. Then there are the secondary, mostly "social" emotions, such as anxiety, grief, guilt, pride, vengeance, and love. These may be unique to humans-hence, at the lower level in our evolutionary mountain landscape and somewhat more liable to cultural manipulation and variation than the primary, "Darwinian" emotions. Thus, only humans seek revenge or redemption across lifetimes and generations, whatever the cost, although the nature of the deeds that trigger insult or remorse may vary considerably across societies, and the means to counter them may range even wider.