About 2,500 years ago something changed the way humans think. Within the span of two centuries, in three separate regions of Eurasia, spiritual movements emerged that would give rise to the world's major moral religions, those preaching some combination of compassion, humility and asceticism. Scholars often attribute the rise of these moral religions—Buddhism, Judaism, Islam, Hinduism and Christianity included—to population growth, seeing morality as a necessary social stabilizer in increasingly large and volatile human communities. Yet findings from a recent study published in Current Biology point to a different factor: rising affluence.

The authors investigated variables relating to political complexity and living standards. Affluence emerged as a major force in the rise of moral religion, in particular, access to energy. Across cultures moral religions abruptly emerged when members of a population could reliably source 20,000 calories of energy a day, including food (for humans and livestock), fuel and raw materials.

“This number appears to correspond with a certain peace of mind,” says lead author Nicolas Baumard, a research scientist at École Normale Supérieure in Paris. “Having a roof over your head, not feeling like the world is full of predators and enemies, knowing that you'll have enough to eat tomorrow.” As Baumard points out, psychology research shows that affluence appears to influence our motivations and reward circuitry away from short-term gain to also considering the benefits of long-term strategy. In other words, with a steady energy supply, we had more time to cooperate, cultivate skills and consider consequences. Affluence also allowed more time for existential pondering: maybe we have some greater moral responsibility; perhaps life has a purpose.

Baumard acknowledges that moral and ascetic qualities probably existed in humans before the major religions emphasizing them. Other experts believe that the paper may not consider these inherent qualities seriously enough. Barbara King, an anthropologist at the College of William & Mary, argues that the study exaggerates the sharp transition to the moral belief systems. She suggests that a more gradual transition may have taken place—one that was perhaps nudged over the line by a reliable calorie count. “Anthropologists and psychologists have found deep roots of morality and compassion in other primates,” King explains. “I don't see any reason to assume that cosmological morality and compassion were not important to earlier hunter-gatherer groups.”

Bernard J. Crespi, an evolutionary biologist at Simon Fraser University in British Columbia, also cautions against Baumard's claim: “The main idea in the article is fascinating, but the causal link between increasing affluence and religion remains to be established. Our work actually suggests that the authors might have their causality reversed—that religion itself drives increases in affluence via its effects on increased cooperation.”

Still, Baumard's findings point to a strong association between affluence and the emergence of moral religion, specifically. Plenty of ancient societies cooperated and had religious beliefs—the Maya, Sumerians and Egyptians among them. For the most part, however, none of these societies' belief systems emphasized morality or material and visceral restraint. And according to Baumard, members of these societies never had access to more than 15,000 calories a day. Whether cause or effect, morality, it seems, takes energy.

The Beginnings of Moral Religion

These five major movements mark the beginning of humanity's turn toward religions that emphasize personal morality and asceticism, according to a new study. —Victoria Stern