Most cultures have a belief in a god (or gods), but only a few believing in a "law giving" god. However, whilst there are relatively few groups with a "king" deity they tend to be much larger than those without it.
A few years ago researchers noticed this pattern. The larger the group, the greater the chance they had a deity bossing them about.
Based on this these researchers speculated that these "gods" may have evolved in these populations to foster co-operation in the larger groups.
Sure enough, subsequent research vindicated this hypothesis. And now more research has done it again!
Speculative science
I n 2012 researchers noticed a strange correlation between group size and belief in a "law giving" king deity.
Only ~5% of societies with less than 1,000 people in believed in a law-giving God. However, more than 40% of groups with >10,000 members believed in such a deity; with an additional 40% also believing in an inactive God. This correlation also followed across group complexity. The greater the level of social complexity in a group, the greater the chance they had a king god.
Based on all this, the researchers speculated that group complexity and size fostered conditions where a king god could "evolve". Humans are good at co-operating with small groups of people, but not 10,000. They hypothesised that these deities - and their commandments to not steal - helped these groups function at such large sizes.
Recently, another study seemed to confirm this. They found that every culture they examined with a king god was more prone to co-operate than those without.
Well, they didn't actually find that they were more prone to co-operate. Rather, they conducted a survey and found that a belief in a law-giving God was correlated with increased levels of empathy, altruism, compliance, and honesty.
And also with increased levels of sexual prudishness.
But just because someone says they're altruistic in a quiz doesn't mean they actually are. That's something which actually needs to be tested. Which is where this latest research comes in.
Actual science
The most recent paper on the subject set out to perform actual experiments on people to see if believing in a law-giving god really did make them more likely to co-operate.
This test consisted of two games. In both, participants are given several coins, two pots, and a die. They have to mentally assign a pot to a side of the die, then role it and place a coin in the pot that comes up. Since the assignation is mental, there is the opportunity to cheat.
In the first test, the pots were labelled "self" and "far away person from the same religion". In the other, it was "nearby person of the same religion" and "far away person of the same religion". In both experiments the coins from the pots were given out to these people. So if someone lied in the "self" game they could profit.
And yet when they had a belief in a law-giving king god (particularly one likely to punish humans for transgression) they didn't lie. They divided up the coins fairly as the die decreed. They were willing to disadvantage themselves (and their neighbours) if they though that is what their deity wanted.
This confirms the hypothesis that these deities help foster co-operation in large groups. Participants were willing to help complete strangers outside their social circle under the influence of their religion.
But what provides extra confirmation is the fact this study was cross-cultural. Individuals from Russia, Brazil, Tanzania, and more, all followed this same pattern. The more they believed in a king god, the more they behaved. It was also cross-religion, with Hindus, Christians, Buddhists, ancestor worshipers, etc. all showing this pattern.
This confirms the research results aren't WEIRD. And confirms the hypothesis that these king gods do foster co-operation. Which raises the question: is this the only factor involved in their evolution, or was there another reason too?
tl;dr
Yet more research has confirmed that there is a strong link between co-operation and "king" gods. Except this time they did it with actual experiments!
References
Peoples, H.C. and Marlowe, F.W., 2012. Subsistence and the evolution of religion. Human Nature, 23(3), pp.253-269.
Purzycki, B.G., Apicella, C., Atkinson, Q.D., Cohen, E., McNamara, R.A., Willard, A.K., Xygalatas, D., Norenzayan, A. and Henrich, J., 2016. Moralistic gods, supernatural punishment and the expansion of human sociality. Nature.
Schmitt, D.P. and Fuller, R.C., 2015. On the varieties of sexual experience: Cross-cultural links between religiosity and human mating strategies. Psychology of Religion and Spirituality, 7(4), p.314.
