A group of researchers from Germany and Canada suggests that humans throughout their evolution might have changed from polygynous societies to monogamous ones because of sexually transmitted infections (STI)
The recent study was published in the journal Nature Communications, were researchers used simulation computer modeling to determine how the interactions between STI’s dynamics and social norms could be explained throughout time.
The authors based their research on diseases such as gonorrhea, syphilis, and chlamydia since they have been present in human populations for a relatively long time and could end up affecting fertility.
Monogamy Vs. Polygynous societies
Chris T. Bauch & Richard McElreath, authors of the study, suggest that human societies were and still are polygynous, yet there was a driven factor that led society to socially imposed monogamy. This factor might have been prehistoric STI’s
According to the research, polygyny is sustainable in a society dominated by small groups, where there are no sights of STI’S. When it came to larger groups the infections became more common and had a serious impact on fertility, which affected the number of the group.
When it came to communities of 30 people or less the outbreaks of infections were limited and short-term. But with communities of 300 people or more the infections seemed to affect larger populations and spread in a much faster way.
These findings could explain, according to the authors, the beginning of socially imposed monogamy.
“It basically suggests that the hypothesis is plausible. I think it’s really a starting point for work that can help us better understand how our social norms are a reaction to our natural environment,” said co-author Chris Bauch who works with his colleague in the Max Planck Institute for Evolutionary Anthropology.
The researchers explain this as the beginning of socially imposed monogamy because men in those early days were believed to be more powerful if they had more wives and children. Yet the outbreak of the infections and the rising of an agriculture market could have led to monogamy.
The agricultural market demanded more healthy men, so to avoid infection and diseases, the number of wives was limited ending in monogamy throughout evolution.