Belief in moral-watching, all-knowing, punitive gods might have helped human societies grow far beyond small, close-knit groups, a new study shows. Researchers who ran an experiment with a total of 591 people in eight different small-scale societies around the world found that people who believed their deity of choice knew about their misdeeds and would punish them were more likely to play fairly in a game where money was on the line.

The findings, described in the journal Nature, hint at the integral role that certain religious beliefs may have played in the dramatic expansion of human societies.

Part of what has made humans as a species so successful is their ability to form social bonds beyond family ties, developing larger and increasingly complex social networks. Many researchers have tried to explore what traits seem to power humans’ ability to cooperate -- sometimes to their individual disadvantage -- for the benefit of the greater good.

This becomes an even more perplexing question as human societies extended beyond the communities where they might either know or be related to everyone they interact with on a daily basis. How do you treat strangers, if you don’t know whether they will abide by the same social rules that you do?


“Throughout the years, there’s been an increasing awareness of how human social complexity is remarkably unprecedented in the animal kingdom,” said lead author Benjamin Purzycki, an anthropologist at the University of British Columbia. “So we’ve got to come up with some satisfactory way of explaining how it’s all possible that we can have remarkably complex societies interact with each other but have quite a fair amount of in-group cooperation and coordination as well.”

Scientists have increasingly found a connection between the type of religion these societies have and their ability to expand, Purzycki said. It’s part of a growing field of research called evolutionary research studies, which looks in part at the way human societies and human belief systems have co-evolved, and how religious beliefs can bring adaptive advantages.

“For quite a few decades, cultural anthropologists have repeatedly observed in a variety of ways that there’s this relationship between the kinds of deities or religious systems that cultures have, and their degree of social complexity,” he said.

Many studies have tried to probe this possible relationship but suffered from a variety of shortcomings, Dominic D.P. Johnson of the University of Oxford, who was not involved in the paper, wrote in a commentary.


See the most-read stories in Science this hour >>

“Empirical evidence that supernatural beliefs promote cooperation is mounting, but has tended to rely on qualitative, society-level or proxy measures of beliefs,” Johnson wrote. “Study participants have also typically been university students in developed nations, thus omitting the small-scale societies most relevant to the evolutionary problem at hand: how human groups achieved cooperation and made the transition from small to large societies in the first place.”

So, to get a better handle on this relationship, the international team of researchers visited eight different small-scale societies around the world to have a total of 519 people play a pair of experimental games. Some, like the Hindu community in the tiny island of Mauritius (east of Madagascar), had both farming and wage labor; others like the Christian community on Yasawa Island (in the Fijian archipelago) had fishing and farming; and still others, like the Hadza of Tanzania, whose gods include the sun and moon, were a hunter-gatherer society.

The researchers went to each community and had participants play a game. Players were given 30 coins, two cups and a six-sided die with three white sides and three painted another color with nail polish or marker. If they put the coin in one cup, it would go to a person of the same religion in a distant village who they’d be unlikely to ever meet. If they put the coin in the other cup, they could keep the money. The players were instructed to think about which cup they wanted to put the coin in. Then they threw the die: If it landed on a painted side, it would go in the cup of their choice; if it landed on a white side, it would go into the opposite cup.


Given that the die had an equal number of white and painted sides, the number of coins that went in the self-cup and the other-cup should, when averaged, fall down a 50-50 split (15 coins in one cup, 15 coins in the other). Here’s the kicker, though: No participants were being watched while they played this game. So -- regardless of which way the die fell -- they could still choose to put the coin in their own cup, without anyone seeing them do it.

The researchers then ran the game a second time, except this time with the cup choices being between a stranger (of the same religion) in a distant location or a local community member of the same religion. They also asked the participants how they felt about their god’s characteristics, including whether the deity was all-knowing, concerned with moral behavior and able to mete out punishment for those who broke the rules. (Later on, the researchers really did take the coins in the “stranger” cups and go to a distant village and hand out the money to surprised strangers -- which was “actually quite a fun part of doing this,” Purzycki said.)

When they ran the numbers, the scientists found that those whose religion featured an omniscient, moral-judging and punitive main deity were more likely to put a coin in the stranger’s cup (14.53 coins in Game 1 and 14.58 in Game 2) than those whose gods would not hold them accountable (12.50 coins in Game 1 and 12.97 in Game 2). In short, their results were more likely to match the 50-50 split (15 coins in the stranger’s cup) than those whose gods were not the all-knowing, punishing type. Fear of supernatural reprisal, it seems, keeps people from cheating.

Why would having the fear of a god in you be a useful trait, as an individual? After all, in this case, it meant that these god-fearing participants gave strangers coins that they could have stowed away for themselves, while those without such punitive deities got more money in the end.


“Deterring oneself from the pursuit of self-interest because of the risk of punishment from a watchful supernatural eye would seem to reduce an individual’s evolutionary fitness, and should thus be eliminated by natural selection,” Johnson wrote. “However, even if such beliefs are false and costly, they may have generated net benefits: to individuals, by steering them away from selfish behavior that risked retaliation in increasingly transparent and gossiping human societies; and/or to groups, by increasing the performance of the group as a whole in competition with other groups.”

Join the conversation on Facebook >>

So having this kind of a deity and religious system could improve group cohesion, make you more likely to behave in less risky ways and allow one group to, say, conquer another one and take over their territory.

Therein, of course, lies the dark side of all these benefits, Johnson pointed out: Increased conflict between groups of people with different religions.


“Whenever the threat of exploitation or warfare is present, the best protection is larger and more-cohesive societies, which are better able to deter or defeat rivals,” Johnson wrote. “Religion’s positive role in reducing self-interest and promoting cooperation may therefore reflect the costs of competition as much as the benefits of generosity.”

Follow @aminawrite on Twitter for more science news and “like” Los Angeles Times Science & Health on Facebook.

MORE SCIENCE NEWS

Zika virus found in fetal brain


Scientists locate the part of the brain where sighs are made

Plastic microbead pollution harms oysters, the ocean’s critical ecosystem engineers, study finds