We often hear natural male polygamy and female monogamy being referred to in the context of scientific fact. This myth, which has no biological foundation at all, was thought up by men back in the day of patriarchy and continues to be supported by men for obvious reasons. No species whose breeding strategy differs among its male and female representatives can ever survive! Nature has no examples of a species in which the males are polygamous and the females monogamous, or vice verse. Either both sexes are polygamous or both are monogamous. Contrary to widespread assumptions, all 'harem-forming' species are totally polygamous i.e. polygamy is evident in both the males and the females. When a lioness is on heat, she will mate with any other male in the absence of the harem leader. The opposite example can be seen among wolves, swans and some other animals, where both male and female are monogamous.
The human species is decidedly polygamous. Polygamous behaviour in men and monogamous behaviour in women emerged in the early stages of patriarchal society, first and foremost as a result of the different physiological roles played by men and women in the task of preserving the common gene, which lead to the withdrawal of women from social and working life for long periods of time after giving birth. We speak about this in more detail in the 9th conversation in The Last Faith. Today, this artificial distinction is still supported in patriarchal societies with a totalitarian religious ideology and low levels of Freedom of Choice, where any attempt a woman makes to step beyond her accepted role could cause her to sacrifice her life through stoning.
There have always existed reasons to justify a gender specific upbringing for boys and girls. I remember the self-education of the boys of my own generation in a country that had recently been released from World War II, when we were breathing the air still saturated with war. At the age of five it was already unthinkable that a boy should cry with pain or walk away from a fight, when faced with the aggression of another boy, otherwise you could find yourself becoming an outcast overnight. They made heroes of us all, preparing us for war and instilling the idea in us that our country was surrounded by a permanently hostile environment. Thank God, these times are passing. Education in the West is becoming increasingly unisex in nature. Boys and girls are bought similar toys and dressed in similar clothing and places in the world, that educate boys and girls separately are becoming all the more rare and archaic.
References:
http://www.bbc.co.uk/earth/story/20160213-why-pairing-up-for-life-is-hardly-ever-a-good-idea
http://www.biologyreference.com/Ma-Mo/Mating-Systems.html