Human sacrifice was part of many traditional cultures across the globe, marking important events like the death of a leader or the construction of a house or boat. These horrific deeds may have had some unexpected benefits, at least for some members of society. According to a religious evolutionary theory called the “social control hypothesis,” social elites may have used human sacrifice to preserve their power, cementing their status by claiming supernatural approval for their acts. The idea makes intuitive sense, but until now there has been no clear evidence to support it. In a recent study, Joseph Watts, a specialist in cultural evolution at the University of Auckland in New Zealand, and his colleagues have analysed 93 traditional cultures in Austronesia as they were before they were influenced by colonization and major world religions, trying to tease out the relationship between human sacrifice and social hierarchy. They find that the prevalence of sacrifice increased with the degree of social stratification: it occurred in 25% of cultures with little or no stratification, 37% of those with moderately stratified societies, and 67% of those that had a pronounced hierarchy. http://www.sciencemag.org/news/2016/04/human-sacrifice-may-have-helped-societies-become-more-complex http://www.nature.com/news/how-human-sacrifice-propped-up-the-social-order-1.19681
I am not sure of the following. It might be valid for one culture & not the other. It is my understanding that the Aztec & Incas sacrificed the best youths in their cultures. If so, the practice would tend to be detrimental. Perhaps there was no such effect due to only sacrificing one or two per year.
