The question itself is novel. Social scientists, for example, have long considered religion as 'sui generis', not as a behavioral predisposition that arose because in some way it contributed to the survival and reproduction of its participants. For Dawkins (The God Delusion) ans Dennett (Breaking the Spell), religion is primarily the misbegotten offspring of memes that promote themselves in human minds: essentially, religion as mental virus, thus something adaptive for “itself” and not for its “victims.” Or it could be a nonadaptive byproduct of something adaptive in its own right. For example, children seem hard-wired to accept parental teaching, since such advice is likely to be fitness-enhancing ("This is good to eat,” “Don’t pet the saber-tooth"). In turn, this makes children vulnerable to whatever else they are taught ("Respect the Sabbath,” “Cover your hair") as well as downright needy when it comes to parentlike beings, leading especially to the patriarchal sky god of the Abrahamic faiths.
For Dawkins in particular, not only is religious belief bad, and unjustified, but, given the susceptibility of young children to adult indoctrination, the very teaching of religion to defenseless children is a form of child abuse. Other, related hypotheses of religion include the anthropologist Pascal Boyer’s grandly titled Religion Explained, which argues that natural selection would have favored a mechanism for detecting “agency” in nature, enabling its possessor to predict who is about to do what (and, often, to whom). Since false positives would be much less fitness-reducing than false negatives (i.e., better to attribute malign intent to a tornado and take cover than to assume it is benign and suffer as a result), selection would promote hypersensitivity, or “overdetection,” essentially a hair-trigger system whereby motive is attributed not only to other people and mastodons, but also to trees, hurricanes, or the sun. Add, next, the benefit of “decoupling” such predictions from the actual presence of the being in question ("What might my rival be planning right now?"), and the stage is set for attributing causation to “agents” whose agency might well be entirely imagined.
Boyer’s work, in turn, converges on that of Stewart Guthrie, whose book, Faces in the Clouds, made a powerful case for the potency of anthropomorphism, the human tendency to see human (or humanlike) images in natural phenomena. The perception of patterns where none exist (some recent, “real” examples: Jesus’ face in a tortilla, the Virgin Mary’s outline in a semimelted hunk of chocolate, Mother Teresa’s profile in a cinnamon bun).
Not all biologically based hypotheses for the evolution of religion are negative, however. In Darwin’s Cathedral, David Sloan Wilson explored the possibility that religious belief is advantageous for its practitioners because it contributes to solidarity, including but not limited to moral codes, that benefits the group and wouldn’t otherwise be within reach. That notion, appealing as it might be, is actually a logical and mathematical stretch for most biologists, relying as it does upon group selection. The problem is that even if groups displaying a particular trait do better than groups lacking it, selection acting within such groups should favor individuals who “cheat.” Mathematical models have shown that group selection can work in theory, but only if the differential survival of religious groups more than compensates for any disadvantage suffered by individuals within each group. It is at least possible that human beings meet this requirement, especially when it comes to religion, since within-group self-policing could maintain religiosity; it certainly did during the Inquisition.
The biologist Lewis Wolpert seeks to examine this problem in a book whose title derives from an exchange between Alice and the Red Queen, in which the latter points out that “sometimes I’ve believed as many as six impossible things before breakfast.” Wolpert describes and interprets various widespread logical fallacies, examining their diverse origins in brain pathology, neurochemical impacts, and other cognitive limitations, in seeking to understand why so many people, in the words of H.L. Mencken, “believe passionately in the palpably not true.” His book is a useful index of hallucinations, confabulations, and other self-delusions, with the intriguing added thesis that much science is itself counterintuitive (the earth’s going around the sun, the mutability of species, quantum “weirdness,” and so on).
Wolpert maintains that “true causal reasoning” is unknown among other animals and often highly flawed in our own species. Yet, as the anthropologist Clifford Geertz has pointed out, people simply cannot look at the world “in dumb astonishment or blind apathy,” and so they struggle for explanation, valid or not, a process that results inevitably in beliefs. Wolpert then suggests that “those with such beliefs most likely did better.” But the bulk of Six Impossible Things Before Breakfast details inaccurate beliefs: How might the holders of false beliefs “do better”? In short, what is the adaptive significance?
One possibility is that faith in an afterlife, in buried golden plates inscribed by divine guidance, or in bright-blue elephant-headed gods is not false after all. Another is that such beliefs have beneficial byproducts, like a placebo. For now, however, it isn’t clear how attachment to one or many gods actually pays off, since, although a deity may have turned water into wine and helped bring down the walls of Jericho in the distant past, such beneficence hasn’t been reliably documented in recent times.
Barbara J. King enters the fray with Evolving God, a knowledgeable trip into the prehistory of religion, enlivened by a refreshing orientation toward nonhuman primates as well as early hominids. Evolving God has the added merit of pushing beyond the Abrahamic “big three,” including a handy account of religious archaeology. King’s touchstone is “belongingness,” the idea that “hominids turned to the sacred realm because they evolved to relate in deeply emotional ways with their social partners, ... and because the human brain evolved to allow an extension of this belongingness beyond the here and now.”
King is convincing about the merits and allure of belongingness, but less so, indeed, she is distressingly silent, when it comes to the adaptive significance of cozying up to the ineffable. If, as she suggests, “at bedrock is the belief that one may be seen, heard, protected, harmed, loved, frightened, or soothed by interaction with God, gods, or spirits,” then what in the real world of biology and reproductive fitness has anchored human biology to that bedrock? A feeling of belongingness sounds nice, as does one of cheerfulness, or the contentment that comes from having a full belly, but to be adaptive, one ought to get a genuinely full belly.
King is quick to dismiss a “genetic approach” to understanding the evolution of religiosity, heaping what may be appropriate scorn on the simplistic, overhyped claim for a “God gene.” But she doesn’t seem to realize that any evolutionary approach is necessarily, at its heart, a genetic one. We must conclude, sadly, that a convincing evolutionary explanation for the origin of religion has yet to be formulated. In any event, such an account, were it to arise, would doubtless be unconvincing to believers because, whatever it postulated, it would not conclude that religious belief arose because (1) it simply represents an accurate perception of God, comparable to identifying food, a predator, or a prospective mate; or (2) it was installed in the human mind and/or genome by God, presumably for his glory and our counterevidentiary enlightenment.
David Hume began his essay The Natural History of Religion (1757) as follows: “As every enquiry which regards religion is of the utmost importance, there are two questions in particular which challenge our attention, to wit, that concerning its foundation in reason, and that concerning its origin in human nature.” So far we’ve been concerned with religion’s “origin in human nature.” Next, its “foundation in reason.”
