Man chooses a mate for life because of bacteria, not real love

An interesting question: why did people become monogamous creatures, rejecting at some point in their evolution polygamous relations, which are natural for most groups of animals? Many people, reflecting on this topic, note that this is associated with the development of morality or religion. Others believe that the reason for abandoning polygamous relationships is love - a feeling that over time became much more valuable to people.

But scientists believe that the answer to this question should be different and lie on a purely physical, not emotional plane. It's all about microbes, they write. According to a new study by experts from the University of Waterloo in Canada, the terrible consequences caused by sexually transmitted diseases (STI) convinced our ancestors that it would be better to have one sexual partner for life.

Primitive people could develop social norms that contributed to the establishment of monogamy, and come up with penalties for polygamy under the influence of those same sexually transmitted diseases, according to Canadian experts.

According to scientists, as soon as hunter-gatherers began to live in large settlements that were previously formed by farmers, sexually transmitted diseases began to spread rapidly. The consequences they provoked could convince people to work out certain social norms of behavior that would help create relationships with one sexual partner over the years.

The study uses computer simulation techniques to simulate the evolution of various social sex relationships in people, based on demographic parameters and indicators of the spread of the disease.

"This study shows how events in natural systems, such as the spread of infectious diseases, can greatly influence the development and establishment of social norms," said Chris Bauch, professor of applied mathematics at the University of Waterloo.

He adds that this research paper illustrates how mathematical models are used not only to predict the future, but also to understand the past.

Researchers found that when the size of the population increased, the presence of sexually transmitted diseases reduced the ability to reproduce offspring among men with multiple sexual partners. In this regard, there was a change in the sexual behavior of people, which showed great benefit for individuals as well as for the group as a whole.

According to experts, in the early settlements of hunter-gatherers it was common that one male had several females for mating (just to increase the number of descendants). In such small societies, where there is a maximum of 30 mature individuals, outbreaks of sexually transmitted diseases were short-lived and, as a rule, did not have a serious impact on the population.

However, after societies began to develop around rural farms, and the size of the population gradually increased, sexually transmitted diseases also began to spread widely across polygamous networks, experts write.

And given the absence in those days of effective drugs for syphilis, chlamydia, and gonorrhea, these diseases probably appeared more and more often. It was then that people realized that it was better to abandon the polygamous relationship, choosing monogamous, as well as blaming the men and women who continued to lead a "licentious lifestyle."

Groups that established monogamous social norms could have supplanted groups that had no such foundations, scientists say.

"Our social norms did not develop in complete isolation; the natural environment was also taken into account. On the contrary, we cannot understand the evolution of social norms without studying their origins in the natural environment," said Chris Bauch.

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