Why Monogamy?

Post Author: Bill Pratt


My friend, Wes, has again recommended to me a great book which I just finished. The book is called Marriage and Civilization: How Monogamy Made Us Human and is written by William Tucker. Here is Tucker explaining what he is going to tackle in the book:

The premise from which we will work is simple. Human monogamy— the pair-bonding of couples within the framework of a larger social group— is not entirely a natural institution. This is attested by the observation that 95 percent of all species are polygamous. Where monogamy has been adopted in nature, it usually involves pair-bonded couples living in isolation in a challenging environment.

Birds pair off within a larger group, which is why in matters of romance we often feel more affinity with them than we do with our fellow mammals; while 90 percent of bird species are monogamous, 97 percent of mammal species are polygamous and individual pair-bonds are almost unknown. Only the beaver and a few others practice monogamy.

Monogamy, then, is not the rule in the natural world, but is the exception. So why was monogamy ever adopted by human beings when most of the animal world is polygamous? Tucker explains that

in almost all species, males spend most of their time fighting among themselves for access to females. The unique social contract of monogamy— a male for every female , a female for every male— lowers the temperature of sexual competition and frees its members to work together in cooperation. It is at this juncture that human societies— even human civilizations— are born.

Tucker spends much of his time in the book defending the hypothesis that monogamous human societies experience greater peace and less violence than polygamous societies. He notes, however, that there is an ever-present danger that monogamy will vanish.

Unfortunately, monogamy does not sustain itself “naturally.” It requires rules —rules that must be continuously enforced by the members practicing it. Moreover, the benefits of monogamy are not distributed equally. There are clear winners and losers, and there will always be pressure against the system from individuals who are dissatisfied with it. Yet any society that responds too enthusiastically to these grievances or decides that the system is no longer worth defending will find itself slipping back into an older social order where male competition is far more intense and the peace of civilization is difficult to maintain.

Why is it that monogamy fosters peace while polygamy fosters violence?

All this can be illustrated with some simple arithmetic. In any animal or human population, there will always be approximately the same number of males and females. When it comes to mating, then, there should be a male for every female and a female for every male . Without the restrictions of monogamy, however, the more powerful males will collect multiple females, leaving the lowest status males with none.

When this happens in nature, the unattached males usually wander off alone to lives that are “nasty , brutish, and short,” or else congregate in a “bachelor herd” where they engage in endless status competitions until one or more emerge as strong challengers to the reigning alpha males. A titanic battle then ensues and if the challenger wins he takes over the “pride,”“pod,” or “harem” of females (there is a name in almost every species). He becomes the new alpha and gets to sire progeny.

So the results of polygamy are that lower status males will be unable to mate because the females have all been claimed by the higher status males. What happens if monogamy is practiced?

Monogamy presents a different picture altogether. If every male is guaranteed a mate, then the losers are high-status males. Their breeding opportunities are curtailed. The winners are lower-status males, who are no longer thrust into exile but are given the opportunity to mate.

There are winners and losers on the female side as well. The winners are high-status females who now have exclusive access to a high-status male instead of having to share him with other females. This is particularly important if the male is a provider. A high-status female who can lay exclusive claim to the efforts of a high-status male provider tremendously increases her chances of raising successful offspring.

At the same time, the fortunes of low-status females are severely constricted by monogamy. They no longer have access to high-status males, either genetically or provisionally, but must be contented with the resources of an inferior, low-status male.

These same lessons can be applied to human civilizations, argues Tucker.

Although all this may seem transparent, its application to the workings of societies both contemporary and historic produces remarkable insights. First of all, it poses the question, how did monogamy ever evolve if high-status males are the biggest losers? After all, it is usually high-status males that dominate a social group and set the rules.

Second, it explains why the predominant pattern in many former civilizations—that of Ancient Egypt or Imperial China, for instance— was polygamy at the top while monogamy prevailed among the common people. The rulers of most ancient civilizations were unabashed in taking multiple wives and consorts— even whole harems. In a few instances— the Ottoman Empire, for example— this stark inequality became so pronounced that the society became basically dysfunctional. On a smaller scale, the same pattern holds in Islamic societies today.

The important point is this. Although monogamy is manifestly a more equitable and successful way to organize a society, it is always under siege and forever fragile. It requires rules that must be upheld by its members. If a society becomes lax or indifferent about upholding its norms, the advantages will quickly unravel— as we are plainly witnessing in the America of today.

Tucker continues, in his book, to provide loads of evidence and argumentation about the pros of monogamy and the cons of polygamy, as illustrated by a variety of human societies, large and small. In future blog posts, I will dig out some of the key arguments and evidence from the book. Stay tuned.

  • sean

    When you reference the idea that America is becoming relaxed in its social norms, forshadowing a polygamous revolution, I can only assume it is in reference to gay marraige legalization. The way marraige is currently defined in the US, with respect to the legal benifits it provides the partners, leaves discrimination between the genders of the partners a useless practice. To suggest that somehow changing a societal norm to not be blatently discriminitory sets us up for a slippery slope to societal doom is absurd. Thee are many examples in history where relinquishing exclusivity on a trade or practice has done no wrong to said society, but has instead simply ended discrimination.

  • Actually gay marriage is not the main issue at all. Tucker’s comment has to do with the high divorce rate, increasing numbers of single parent families, and the overall attempt by the media and intellectual elite to marginalize and ridicule the traditional institution of monogamous marriage.

  • sean

    Oh, well never mind. I’ve much less of a problem with that statement. Divorce isn’t bad, per se, in that it indicates people are getting out of bad relationships, but such high rates do point to people possibly rushing into marragie with people they maybe shouldn’t have. I don’t want to come across as dissing single parents, because I very much value what they do, but it is certianly more difficult to raise children without two parents, and it’s very disappointing to see people walking out on their children like that. Not sure I’m as on board with the media bashing as a thing. I’m not trying to assert that I know it’s not happening, just that I’m not too familiar with it occuring. I don’t know if you’re going to cover it in upcoming posts, but I’d be curious to know more.

    On a side note, could you explain what’s up with the recent comments box being filled by links to stuff instead of comments? I’m just curious. I’d assume it’s some sort of bug with Disqus.

  • The comment spam has increased exponentially in the last several months and the spam filters simply aren’t catching everything. I am having to clean up more spam manually than I have in the past. It’s really annoying!

  • By the way, Tucker’s comments about gay marriage are interesting. I will be covering them in an upcoming post.