So how did this God gene flourish? Wade’s counterintuitive answer repurposes an old social-scientific analysis of religion as a saga of biological survival. Rituals take time; sacrifices take money or its equivalent. Individuals willing to lavish time and money on a particular group signal their commitment to it, and a high level of commitment makes each coreligionist less loath to ignore short-term self-interest and to act for the benefit of the whole. What are gods for? They’re the enforcers. Supernatural beings scare away cheaters and freeloaders and cow everyone into loyal, unselfish, dutiful and, when appropriate, warlike behavior.

Image Credit... Illustration by Timothy Goodman

Wade walks us briskly through the history of religion to show how our innate piety has adapted to our changing needs. Hunter-gatherers were egalitarian and, shamans aside, had direct access to the divine. But when humans began to farm and to settle in cities and states, religion became hierarchical. Priests emerged, turning unwritten rules and chummy gods into opaque instruments of surveillance and power. Church bureaucracies created crucial social institutions but also suppressed the more ecstatic aspects of worship, especially music, dance and trance. Wade advances the delightfully explosive thesis that the periodic rise of exuberant mystery cults represent human nature rebelling against the institutionalization of worship: “A propensity to follow the ecstatic behaviors of dance and trance was built into people’s minds and provided consistently fertile ground for revolts against established religion,” he writes.

There’s a safari-hatted charm to Wade’s descriptions of what he calls, a little jarringly, “primitive” religion, filled with details of the rites of tribes cut off from the modern world but still available for anthropological observation. But his ­sketches of Judaism, Christianity and Islam rush by quickly and confusingly and offer only superficial accounts of the spread of those faiths, which was in each case a dicier process than Wade makes it sound. (What if Constantine had held out against the Roman Empire’s Christian factions, instead of converting?) Judaism’s strict moral codes, he argues, held together the rival states of Israel and Judah in Biblical times and provided comfort to Jews in exile, but failed to accommodate the more diverse Jews of the first-century Hellenic world. Early Christians adapted Judaism’s attractive but exclusivist mores to a society that had outgrown tribalism, succeeding “so well that they captured an empire and defined a civilization.” Wade embraces a radically revisionist approach to Islam, which holds that it evolved out of a Syriac branch of Christianity whose members believed that Jesus was human and rejected the Trinity. This sternly monotheistic remnant was Arabized when a new dynasty needed to differentiate itself from a previous one. If the revisionist version of Islam is correct, Wade writes, it “furnishes a case study of how a religion can be adapted with great success to a state’s purposes.”

Wade would probably deny that being adaptive makes any religion better in a non-evolutionary sense than any other. His scientist’s neutrality slips toward the end of the book, however, when he starts making the case for Religion with a capital R. Like Robert Wright in “The Evolution of God,” Wade wants to defend religion from so-called “new atheists” like Richard Dawkins, Daniel Dennett and Christopher Hitchens, who see it as a malignant illusion. In chapters on religion and trade, religion and warfare, religion and nation, and the “ecology” of religion — the way in which religion regulates fertility and population size — Wade argues that our religious disposition can enhance social and national unity, manage scarce resources, even solve the tricky problem of how to get young men to die for the greater good when that’s called for. But Wade also knows that the faith-based preference for the group has engendered genocide, mass suicide and maladaptive cargo cults. Perhaps that is why he declines to draw one inference that proceeds from his arguments: that individual religions can be compared and ranked and, well, approved or disapproved of, since a religion can be good only insofar as it’s useful.

In any case, Wade says, religion is not going away, because it’s imprinted on the human genome. The first part of this claim is hard to argue with. The second part is probably true, too, but raises the question of how. Wade’s vision of religion as a socializing force is persuasive, but he does not do enough to distinguish socially efficacious religious beliefs from, say, socially efficacious political ideologies. There are biologically or at least neurologically grounded accounts of religion, like Boyer’s, that more successfully capture the weird particularity of religious experience while also revealing its tentacles in many other facets of mental and emotional life. Ask yourself: Why are our gods always equipped with recognizably human minds, even when they’re animals? How do sacred stories differ, if they do, from fairy tales, or from novels? What are holiness, impurity and ritual, exactly, and are they religious in essence, or categories implicated in everything we think and do?