A man’s commitment to reproduction is short and pleasurable; a woman’s is long and arduous.
From this simple truth arises most of our social conventions, societal norms, and expectations when it comes to the sexes interacting with one another.
In the absence of the state (whose interference will be discussed in a future installment), it becomes imperative that women not only choose fit partners, but require those partners to contribute resources and support offspring. The problem is that the fun, fulfilling part of male reproduction happens first while all the work that arises from it happens afterwards. There is a good evolutionary reason for this – reproduction would likely happen far less often if the hardships of parentage happened before the physical satisfaction that creates the sex drive. Institutions like marriage are the social response to such a need. In order for a man to gain access to sex, he has to pledge a material commitment, both of present and future means, to the woman and her offspring.
Binding up resources in reproduction, and therefore marriage, also creates another societal norm: Monogamy. Monogamy, which is having only a single sexual partner, becomes a necessary demand from both people in a marriage, though the strength of such demands has varied by culture. The man demands that his partner remain monogamous so that he can be assured the offspring is indeed his, and the woman demands monogamy so as to maximize her access to the man’s resources. Like the pleasure of the sexual encounter, this exchange also makes biological sense, even if it is a cultural or behavioral response to biology. Evolution, after all, is selfish rather than altruistic. Behaviors that contribute to the passing on of one’s own genes are the driving force of evolution, not behaviors that contribute to the survival of the species in general, or even a population. It is through the survival and reproduction of the fittest individuals that a species survives. If a man contributed survival resources to offspring that was not his own it would represent biological failure.
There is debate as to whether the female demand is a strong as the male demand historically, as evidence of past cultures suggests that male fidelity was not always expected (as a cursory exploration of Japanese and Roman historical culture – far flung as they are – will reveal). However, through the vast majority of these cultures there is an expectation that the primary reproductive and wealth collecting institution, marriage, would remain unhindered by extra-marital encounters by the man. This is why illegitimate offspring in past periods were so pitied; they could not officially demand nor inherit the wealth of the father. This made marriage a highly preferable state for women, and therefore created a demand on men. The modern state institution of marriage places more practical monogamy demands on men, since the government can collect with force support funds from illegitimate offspring.
Polygamy, which existed in many forms from the ancient to the modern, usually involved the pairing of several women with one man. The man’s demand of monogamy from the woman was still intact. Historically, most men who had multiple wives controlled large amounts of resources with common men in such cultures still involving themselves with a single wife due to practical limitations. Either way, the exchange of monogamy for resources is a constant and logical trade.