Human societies hit a ‘God threshold’ at around one million people where they need a moralising, rule-making deity to keep order, a new study suggests.

Previously it was thought that the expansion of complex societies went hand-in-hand with controlling religions, which installed principles of right and wrong and allowed large numbers to live together peacefully.

But a new study by Oxford University and Keio University in Japan, found that only ‘megasocieties’ of more than one million require the kind of unyielding cohesive beliefs that gave rise to major religions like Christianity, Judaism, Islam or Buddhism.

The authors looked at 414 societies, spanning the past 10,000 years from 30 regions around the world, measuring social complexity and the supernatural enforcement of morality.

They found that contrary to previous predictions powerful ‘big gods’ with their fearful supernatural punishments followed the emergence of large scale cooperation, proving religion is not just a ‘historical accident’ but is a fundamental part of human evolution.

Co-author Harvey Whitehouse, Professor of Social Anthropology, at Oxford University said: “What we think might be happening around the time that societies hit the one million population mark is that they become vulnerable to internal structural tensions and conflict, perhaps because they somehow have to hold together multiple ethnic groups as a result of processes of expansion and incorporation.