Research Suggests that Monogamy Took Hold Due to Sexually Transmitted Diseases
In the animal world, monogamy refers to a pair that have an exclusive sexual relationship during the period of breeding and rearing of offspring. With respect to humans, it is a model of affective-sexual relations based on an idea of exclusivity for a period of time - which could last a lifetime, between two people united by a sentimental attachment.
Human, socially imposed monogamy, as Agencia SINC explains, is something of an evolutionary puzzle, for the efforts and sacrifices required by those who accept it. Scientists had always believed that the much-debated idea of monogamy was established after the advent of agriculture and the creation of more modern human societies. However, a new study suggests that sexually transmitted diseases (STDs), also known as Sexually Transmitted Infections (STIs), had an important role in the establishment of monogamy as a common model for human coexistence.
According to a study recently published in the journal Nature, the appearance of multiple STDs, along with the birth of agriculture, forced prehistoric men and women to develop partnerships formed by larger groups. This new way of life, with its internal pressures due to contact with the same population, led to the establishment of the first social standards, causing a change from polygamy to monogamy.
Male orangutans are not monogamous, and compete for mating with different females. In the picture, a male, female, and child Sumatran orangutans (pongo abelii). (Jeffery J. Nichols/CC BY-SA 3.0)
"In smaller societies, sexually transmitted infections cannot persist long-term, they disappear due to random events, which are also more common in small groups. Therefore, polygamy is not disadvantaged because infections do not persist. In larger populations, infections are able to persist and this is what makes polygyny less advantageous than monogamy, since the average level of infection is higher in polygynous groups than in monogamous groups,” Chris Bauch, leader of the study and a scientist at the University of Waterloo in Canada, explained to Agencia SINC.
The researchers used a model based on different variables to simulate how STDs may have affected primitive societies: “This essentially means that we simulated a real population of hunter-gatherers and farmers who acted according to certain rules, and saw how an infection spread among individuals according to these rules. It's a bit like a computer game” Bauch continued.
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It is appropriate, at this point, to remember that the first human groups were formed by hunter-gatherers, in which it was normal that a few males monopolized mating with multiple females, thus increasing their number of offspring. In those small and emerging societies, which were often made up of a maximum of 30 adult individuals, outbreaks of STDs were short-lived and did not usually cause major impacts among its members. However, in larger social groups, these infections became endemic, which in itself would have exerted a great impact on their fertility and survival.
The researchers simulated a model of a real population of hunter-gatherers and farmers who acted according to certain rules. In the picture, a San in Namibia. Less than 10,000 San currently live by hunting and gathering. (Ian Beatty/CC BY-SA 2.0)
"We do not have much information on the prevalence of sexually transmitted diseases in prehistoric populations, although there are examples of outbreaks of sexually transmitted diseases in isolated groups of hunter-gatherers today. We can use this data from modern populations to test the model, that would be a future project in this area of research," Bauch told Agencia SINC.
Lastly, Bauch told the National Post that the implications of the study for today’s societies varies, however he stressed the “importance is understanding where our social norms began and why.” He said:
“Humans are impacted by transmissions, but they also change them by changing their behaviors. They served a purpose and evolved in response to our natural environment. Not only does our environment influence us, but we influence the environment.”
Featured Image: ‘Two Lovers’ (c. 1629-1630) by Reza Abbasi. Metropolitan Museum of Art in New York, USA. (Public Domain)
By Mariló T. A.
This article was first published in Spanish at http://www.ancient-origins.es and has been translated with permission.