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Key points
- It is only relatively recently, around 10,000 years ago, that monogamy began to prevail over polygamy.
- Historically, most cultures that permitted polygamy permitted polygyny, rather than polyandry.
- For both men and women, polygyny has pros and cons.
In the state of nature, people were generally polygamous, as are most animals. With many animals, the male leaves the female soon after copulating and long before any offspring are born. A male bear is liable to kill and eat any bear cub that it encounters, even if the cub happens to be its own. On the other hand, over 90 per cent of avian species are socially monogamous, as are the emperor penguin, the prairie vole, and the red-backed salamander. The flatworm Schistosoma mansoni, one of the major agents of the parasitic disease schistosomiasis (bilharzia), is monogamous in its male-female pairings within the human body—challenging the common prejudice that monogamy is more sophisticated, or ‘higher order’, than polygamy.
According to genetic studies, it is only relatively recently, around 10,000 years ago, that monogamy began to prevail over polygamy in human populations. A rise in monogamous unions may have been tied to the development of sedentary agriculture, helping to maintain land and property within the same narrow kin group.
Polygamy may enable a male to sire more offspring, but monogamy can, in certain circumstances, represent a more successful overall reproductive strategy. By sticking with the same female, a male can be more or less sure that the female’s offspring are also his, and protect this offspring from being killed by male rivals intent on returning the female to fertility (breastfeeding being a natural contraceptive).
Historically, most cultures that permitted polygamy permitted polygyny (a man taking two or more wives) rather than polyandry (a woman taking two or more husbands). In his first-hand account of the Gallic Wars, Julius Cæsar says that, among ancient Britons, ‘ten and even twelve men have wives in common,’ particularly brothers, or fathers and sons—which sounds more like group marriage than polyandry proper.
Polyandry is typically tied to scarcity of land and resources, as, for example, in certain parts of the Himalayas, and serves to restrain population growth. If it involves several brothers married to the same wife (fraternal polyandry), it also protects the family’s land and assets from division.
In Europe, this preservation of patrimony was generally achieved through the feudal rule of primogeniture (‘first born’), still practised today among the British aristocracy, by which the eldest legitimate son inherits the entire estate (or almost) of both parents. Primogeniture has antecedents in the Bible, with Esau selling his ‘birthright’ to his younger brother Jacob.
Polygamy Today
Today, most countries that permit polygamy—invariably in the form of polygyny—are countries with a Muslim majority or sizeable Muslim minority. In some countries, such as India, polygamy is legal only for Muslims. In others, such as Russia and South Africa, it is illegal but not criminalized.
Under Islamic marital jurisprudence, a man can take up to four wives, so long as he treats them all equally. But while it is true that Islam permits polygyny, it does not require or impose it: in principle, marriage can only occur by mutual consent, and a bride is able to stipulate that her husband-to-be is not to take a second wife. Monogamy is by far the norm in Muslim societies, as most men cannot afford to maintain more than one family, and of those who can many would rather not. Still, polygyny remains common across much of West Africa, rooted in part in the trans-Atlantic slave trade, which, for a long time, led to important gender imbalances in those regions.
Polygamy is criminalized across Europe and the Americas, as well as in China, Australia, and other countries. Even so, there are many instances of polygamy in the West, especially within immigrant communities and religious groups such as the Fundamentalist Church of Jesus Christ of Latter-Day Saints (FLDS Church) and other Mormon fundamentalists.
The Pros of Polygamy
What are the pros and cons of polygamy (or polygyny)? A man who takes more than one wife satisfies more of his sexual appetites, signals high social status, and generally feels better about himself. His many children supply him with a ready source of labour, and the means, through arranged marriages, to create multiple, reliable, and durable economic, social, and political alliances. Polygyny may be costly, but in the long term it can make a rich man richer still.
Even in monogamous societies, powerful men often establish long-term sexual relationships with women other than their wives (called concubinage), although in this case the junior partners and the children born to them do not enjoy the same legal protections as the formal or ‘legitimate’ wife and children. The Sun King, Louis XIV of France, had several official and unofficial mistresses. His chief mistress at any one time carried the title of maîtresse-en-titre [‘official mistress’], and the most notorious one, Françoise-Athénaïs, Marquise de Montespan, bore him no fewer than seven children.
In some cases, a man—most famously Henry VIII of England—might get divorced to marry a much younger woman (serial monogamy), thereby monopolizing the reproductive lifespan of more than one woman without suffering the social sanctions of polygamy.
If divorce has become so common, it is in part because people are living for much longer, whereas in the past death would have done the job of divorce. ‘Till death do us part’ means a great deal more today than it ever has.
Polygyny might even benefit the women involved, who may come to enjoy one another’s company, and share out the burdens of housekeeping and childrearing. Younger wives may add to the status and standing of the first wife, while subtracting from her responsibilities.
In times of war, with high male absenteeism and mortality, polygyny supports population growth and replenishment by ensuring that every female can find a mate.
The Cons of Polygyny
But of course polygyny also has drawbacks, especially when viewed through a modern, Western lens. First and foremost, polygyny sanctions and perpetuates gender inequality, with co-wives officially and patently subordinated to their husband.
Women in polygynous unions tend to marry at a younger age, into a setup that is bound to foster jealousy, competition, and conflict, with instances of co-wives poisoning one another’s offspring in a bid to advance their own.
Although the husband ought in principle to treat his co-wives equitably, in practice he will almost invariably favour one over the others—typically the youngest, most recent one. Tensions may be reduced by establishing a clear hierarchy among the co-wives, or if the co-wives are sisters (sororal polygyny), or if they each keep a separate household (hut polygyny).
While polygyny may benefit the men involved, it denies wives to other men, especially young, low-status men, who, like all men, tend to measure their success by their manhood, that is, by the twin parameters of social status and fertility. With so little to lose and look forward to, these frustrated men are much more likely to turn to crime and violence, including sexual violence and warmongering—and it is perhaps telling that polygamy is practiced in almost all of the 20 most unstable countries on the Fragile States Index.
These social inequalities are only aggravated by the brideprice, a payment from the groom to the bride’s family. Brideprice is a frequent feature of polygynous unions, and intended to compensate the bride’s family for the loss of a pair of hands. Divorce typically requires that the brideprice be returned, leaving many women with no choice but to remain in miserable or abusive marriages. If polygynous unions are common enough, a resulting shortage of brides inflates the brideprice, raising the age at which young men can afford to marry while incentivizing families to hive off their daughters at the earliest opportunity, even at the cost of interrupting their education. Brideprice is often paid in cows, leading some young men to resort to cattle raids and other forms of crime. Gang leaders and warlords attract new recruits with the promise of a bride or an offer to cover their brideprice.
Polygyny also tends to disadvantage the offspring. On the one hand, children in polygynous families share in the genes of an alpha male (or, at least, an upper-class male) and stand to benefit from his protection, resources, influence, outlook, and expertise. On the other hand, their mothers are younger and less educated, and they are set to receive a divided share of their father’s attention, which may be directed at his latest wife, or at amassing resources for the next one. Children in polygynous families are also at greater risk of violence from their kin group, especially the extended family. Overall, infant mortality in polygynous families is significantly higher than in monogamous families.
So, draw your own conclusions.
Read more in For Better For Worse: Essays on Sex, Love, Marriage, and More.
References
Dupanloup I et al. (2003): A recent shift from polygyny to monogamy in humans is suggested by the analysis of worldwide Y-chromosome diversity. J Mol Evol. 57(1):85–97.
Fragile-States Index 2017. The Fund for Peace; DHS; MICS.
