Sexually transmitted infections (STIs) may have helped foster monogamy in some human societies, according to a new study.

Researchers found that when a society is large the prevalence of STIs becomes endemic, reducing fertility rates and favouring the emergence of monogamists in society. However in smaller groups, with a maximum of 30 people, STI outbreaks are short-lived and do not become endemic in the population. This allows polygynous societies to flourish thanks to high fertility rates and the low impact of disease.

The research team reached their conclusions by simulation the evolution of different social mating norms by modelling demographics and disease transmission rates.

Original research paper published in Nature Communications on April 12, 2015.

Names and affiliations of selected authors

Chris Bauch, University of Waterloo, Department of Applied Mathematics, Ontario