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Human Sacrifices Maintained Social Power Structures

A new study has reported that ritual human sacrifice played a central role in helping those at the top of the social hierarchy to maintain power over those at the bottom. “Religion has traditionally been seen as a key driver of morality and cooperation, but our study finds religious rituals also had a more sinister role in the evolution of modern societies,” says lead author Joseph Watts, a PhD candidate at the University of Auckland’s School of Psychology.

The study, published in Nature (, used computational methods derived from evolutionary biology to analyse historical data from 93 Austronesian cultures, 40 of which practised some form of ritualistic human killing. Early Austronesian people are thought to have originated in Taiwan and eventually settled almost half the globe. They spread west to Madagascar, east to Rapa Nui (Easter Island) and south to the Pacific Islands and New Zealand.

Methods of ritual human sacrifice in these cultures included burning, drowning, strangulation, bludgeoning, burial, being cut to pieces, crushed beneath a newly-built canoe or being rolled off the roof of a house and decapitated. Victims were typically of low social status, such as slaves, while instigators were usually of high social status, such as priests and chiefs.

The study divided the 93 different cultures into three main groups of high, moderate or low social stratification. Cultures with the highest level of stratification were most likely to practice human sacrifice (67%, or 18 out of 27). Of cultures with moderate stratification, 37% used human sacrifice (17 out of 46) while the most egalitarian societies were least likely to practise human sacrifice (25%, or five out of 20).

“By using human sacrifice to punish taboo violations, demoralise the underclass and instil fear of social elites, power elites were able to maintain and build social control,” Watts says.

Prof Russell Gray, a co-author of the study, notes that “human sacrifice provided a particularly effective means of social control because it provided a supernatural justification for punishment. Rulers, such as priests and chiefs, were often believed to be descended from gods, and ritual human sacrifice was the ultimate demonstration of their power.”

The team’s use of computational evolutionary methods enabled the team to reconstruct the sequence of changes in human sacrifice and social status over the course of Pacific history. This allowed them to test whether sacrifice preceded or followed changes in social status.

“What we found was that sacrifice was the driving force, making societies more likely to adopt high social status and less likely to revert to egalitarian social structure,” said co-author A/Prof Quentin Atkinson.