I’ve been meaning to write about this paper for some time, but it’s fallen into my backlog of 1000-odd draft posts that I almost never look at. However, I found a printout in my daypack, and so will try to describe it briefly, for the results are somewhat hard to interpret.

The paper, in a January, 2016 issue of Nature, is by Benjamin Grant Purzycki et al. (reference and free download below). The authors’ motivation is this: why, in a world in which we’re far removed from many of the people we interact with, do we still behave nicely and practice reciprocity? After all, we’re not related to those people, so kin selection can’t apply, nor do we live in small bands with them, in which reciprocity is de rigueur because you constantly deal with your groupmates and can’t afford to get a bad reputation. Why don’t we just cheat?

There are many answers, including Peter Singer’s combination of evolution and rationality described in his book The Expanding Circle, and my own theory (which is mine) that one’s reputation also extends distantly these days. (If you cheat in your internet business, you’re not going to do very well.) But Purzycki et al. had another hypothesis involving religion and God. The authors suggest that if you believe in a “moral and punitive god,” the more likely you’d be to distant people who belong to your religion. After all, that god is watching you and will punish you if you’re not generous or fair.

To test whether this hypothesis was true, the authors did a laboratory study with people from eight diverse communities throughout the world, holding a variety of different belief systems. Each society (shown in the table below) had both a general, moralistic god as well as a “local god” (for Christians, the Big God and the Virgin Mary respectively).

To test the effects of a moralizing god (as well as less omnipotent or omniscient local deities), the authors played two games with each of the 591 subjects, games described in the diagram below. In each case the participant was given 30 coins, which stood for stuff like money or corn, so your allocation reflects what you really got (and the stuff you gave away was also really given away). Subjects were also questioned about the degree to which local gods and Big gods cared about morality (local gods always cared less).

In each test, you allocated your 30 coins between two labeled cups. First, you were asked to mentally choose which cup you wanted to put one of your coins into. Then you were asked to roll a die on which three faces had a single color, and the other three faces another color. If a specified color came up, the subject was asked to put a coin into the cup that was mentally chosen. If the other color came up, you were asked to put a coin into the other cup. Each of the cups were labeled as to the nature of the recipient. The two choices were these:

Self game.  One cup indicated as “self” (i.e., the player); the other as “distant co-religionist” (the paper doesn’t say how distant).

Local co-religionist game. One cup indicated as “local co-religionist”, presumably someone in your community; the other cup indicated as “distant co-religionist”.

Voilà:

Under these conditions, of course, 50% of the coins would, on average, go into each of the two cups. But you could bias the results by cheating, either by not throwing the die, or putting coins into cups contra what the die dictated. Nobody watched the participants, though they thought their gods were watching.

The results:

• When results were classified, as in the graph below, by answers to the question “does your god punish you,” people put fewer coins in the distant co-religionist cup (i.e., what the subjects themselves didn’t get), than they did when they thought the god was more punitive (bars left to right in figure).  The number of coins allocated toward distant co-religionists compared to the alternative choice increased by a factor of 4.8 in the self game and 5.3 in the local co-religionist game.

• On average, then, players gave two more coins to the distant-coreligionists when they thought their god was very punitive than when they didn’t know whether their god was punitive. In other words, they were nicer to distant members of their faith when they thought their god was watching and would punish selfishness.

• Note, though that in all cases the average number of coins given to distant co-religionists was less than half of what you expect under the 50:50 distribution, so even a very punitive god didn’t enforce perfect fairness (the error bars in the latter case do encompass 15 coins, though).

• Finally, looking at the effect of other variables on the responses, including stuff like economic conditions, education, and number of children, the authors found that only the degree of punitive-ness or omniscience of the moralistic god was correlated with the results, while the effect of other variables, including local gods, wasn’t significant.

The authors conclude that their results have big implications for understanding cooperation between distant people:

These results build on previous findings and have important implications for understanding the evolution of the wide-ranging cooperation found in large-scale societies. Moreover, when people are more inclined to behave impartially towards others, they are more likely to share beliefs and behaviours that foster the development of larger-scale cooperative institutions, trade, markets and alliances with strangers. This helps to partly explain two phenomena: the evolution of large and complex human societies and the religious features of societies with greater social complexity that are heavily populated by such gods. In addition to some forms of religious rituals and non-religious norms and institutions, such as courts, markets and police, the present results point to the role that commitment to knowledgeable, moralistic and punitive gods plays in solidifying the social bonds that create broader imagined communities

But I don’t buy that for a number of reasons. People are often altruistic towards those of different faiths. Further, the experiment was done in a lab, and it’s not clear how well this short-term experiment translates toward behavior in real life. Finally, the authors use the data to explain why some religions spread at the expense of others (people of those faiths help each other, even when far away), but there is no control study about how people behave towards other people who don’t share their faith.

In other words, this experiment, while showing that the idea that a punitive god is watching may make you give more coins to distant coreligionists than you otherwise would, doesn’t say much to me about the author’s Big Thesis. Yet the paper was published in Nature, one of the world’s most prestigious and hard-to-get-into journals. I can conclude only that Nature‘s editors like the result. Perhaps they have belief in belief.

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Purzycki, B. G. et al. 2016. Moralistic gods, supernatural pubishment and the expansion of human sociality. Nature 530:327-330.