Monogamy in most human cultures may be the result of sexually transmitted diseases, according to the results of newly-released computer simulation. The presence of these infections could have resulted in serious societal pressures, altering sexual behavior, researchers argue.
Early humans started to live together in larger groups as agriculture became more prevalent. Sexually-transmitted diseases (STD's) among inhabitants in these larger, denser populations may have driven our ancestors to develop societal norms rewarding monogamous behavior.
University of Waterloo researchers utilized computer models to simulate social mating behaviors in prehistoric human societies. The team examined the transmission of disease within various demographics in the simulation in order to determine how our ancestors may have altered their behavior over time.
"This research shows how events in natural systems, such as the spread of contagious diseases, can strongly influence the development of social norms and in particular our group-oriented judgments. Our research illustrates how mathematical models are not only used to predict the future, but also to understand the past," said Chris Bauch of the University of Waterloo.
Prior to the widespread adoption of agriculture, it was common for a select group of males to each mate with several females. In groups of fewer than 30 sexually-active adults following this practice, any outbreak of STD's was usually limited in scope and duration.
However, as the number of people living together began to grow, the incidence of STD's likely became more common. Males who limited themselves to a single mate were more likely than polygamous males to produce offspring. Over time, groups which rewarded monogamy may have been more successful than other bands of early humans, reinforcing the societal norm.
Without modern means of preventing transmission of disease, the prevalence of STD's may have run rampant. Before contemporary medicine, infections would have gone untreated, severely hampering people exposed to the diseases.
Researchers point out that social norms and natural events may have influenced one another as human culture developed long ago. Other factors, including the impact of early technology, selection of males by females, and the development of pathogens may have also played roles in the rise of monogamy.
Analysis of the role STD's may have played in the development of monogamous relationships was profiled in the journal Nature Communications.