The research, published online today in the Proceedings of the National Academies of Science, combines social and ecological data to build a predictive model for the global distribution of beliefs in big gods.
The lead author of the study, Dr Carlos Botero, a researcher at the Initiative for Biological Complexity at North Carolina State University, worked with Professor Russell Gray from the University of Auckland and Dr Joseph Bulbulia from Victoria University of Wellington.
Dr Bulbulia says the highly interdisciplinary team combined cultural and political information from 583 societies around the world with extremely high resolution climate datasets to produce its findings.
The study finds that just as physical adaptations help populations prosper in unhospitable habitats, belief in moralising high gods might be similarly advantageous for human cultures in poorer environments.
The study also indicates that societies with less access to food and water are more likely to believe in these types of deities.
In addition, the researchers found a strong correlation between belief in high gods who enforce a moral code and other societal characteristics. Political complexity—namely a social hierarchy beyond the local community— and the practice of animal husbandry were both strongly associated with a belief in moralising gods.
“Previous studies have pointed to religion being a force for building strong social groups but there has, until now, been no systematic global test of the social bonding hypothesis,” says Dr Bulbulia.
While there have been studies showing that natural calamities are associated with religious conversion, including one involving Dr Bulbulia carried out in Christchurch after the earthquake, he says overall the extent to which ecology shapes religion around the world remains fascinatingly unclear.
Primary author Dr Carlos Botero says: “When researchers discuss the forces that shaped human history, there is considerable disagreement as to whether our behaviour is primarily determined by culture or by the environment.
“We wanted to throw away all preconceived notions regarding these processes and look at all the potential drivers together to see how different aspects of the human experience may have contributed to the behavioural patterns we see today.”
The study began with a National Evolutionary Synthesis Center (NESCent) working group that explored the evolution of human cultures.
On a whim, Dr Botero plotted ethnographic data of societies that believe in moralising, high gods and found that their global distribution is quite similar to a map of cooperative breeding in birds. The parallels between the two suggested that ecological factors must play a part. Furthermore, recent research has supported a connection between a belief in moralising gods and group cooperation.
“The goal became not just to look at the ecological variables, but to look at the whole thing,” says Dr Botero. “Once we accounted for as many other factors as we could, we wanted to see if we could still detect an environmental effect.
“The overall picture is that these beliefs are ultimately shaped by a combination of historical, ecological, and social factors.”
Dr Bulbulia says the research offers a blueprint for how multi-disciplinary teams from across the natural sciences and humanities can work together to use empirical evidence to address controversial questions about the human condition.
“We think we find an association between religion, climate, and political complexity because religion fosters strong social bonds which help people to cooperate. Such bonds are especially important in harsh/unpredictable environments.”
However the dark side of highly-united social groups is intergroup violence says Dr Bulbulia. “In future work, we hope to better understand the factors that link religion in some regions of the world with peace, and in other regions of the world with violence.”
The team involved in the research included experts in biology, ecology, linguistics, anthropology, religious studies (Dr Bulbulia), the intersection of psychology and linguistics (Professor Gray) and the behaviour of birds (Dr Botero, an evolutionary ecologist).
The research was supported by the National Science Foundation, the National Evolutionary Synthesis Center and the John Templeton Foundation in the United States and the Royal Society of New Zealand through the Marsden Fund.