Federal authorities recently raided the compound of a polygamous Mormon sect in Eldorado, Texas, after allegations that underage girls were being sexually abused. Why is polygamy illegal, and why is it still practiced?

What is polygamy?
The term polygamy, strictly speaking, describes any long-term, consensual mating arrangement in which the total number of partners is greater than two. In its common usage, however, the term generally denotes one specific form of polygamy: polygyny, the practice of one man having multiple wives. The other kind of polygamy, polyandry, whereby one female has multiple husbands, is not unheard of—some nomadic Tibetan cultures practice a form of it, as has the Toda tribe of India. But for reasons that probably have something to do with the nature of male sexuality, polyandry never really caught on the way polygyny did.

Who practices polygamy?
Throughout the world, millions of people. Anthropologists estimate that three-quarters of human societies have, at one point or another, allowed a man to take more than one wife, and that even today roughly a third of the world’s population lives in a community that tolerates polygamy. That includes much of the Middle East—Jordan, Syria, Iraq, Iran, and Israel—and most of the Muslim nations of North Africa. Even in the United States, where polygamy is illegal, there are an estimated 50,000 people living in polygamy, the vast majority of them “Mormon fundamentalists”—a contentious term, as we’ll see in a moment.

What does Mormonism have to do with it?
Joseph Smith, the founder of Mormonism, had a revelation that God not only tolerated polygamy—he required it. On July 17, 1831, Smith said, God told him that only a man with at least three wives could enter heaven. In Mormon theology, the individual human soul exists both before and after mortal life, and it is therefore the duty of all Mormon men to have as many children as possible, thus sparing those souls the indignity of being born, as the Mormon apostle Orson Pratt put it, “among the Hottentots, the African negroes, the idolatrous Hindoos, or any other fallen nations that dwell upon the face of the Earth.” So-called plural marriage was seen as a means to that end, not to mention increasing the then-tiny sect’s number of followers.

So why aren’t all Mormons polygamous?
Because God changed his mind. In 1890, after Smith’s death, the Utah Territory was applying for recognition as a federal state, but the government insisted that first Utah had to outlaw polygamy. Happily for all concerned, however, church president Wilford Woodruff received a revelation from God during prayer to the effect that Mormons were now to submit themselves to U.S. law and cease the practice of plural marriage. To some church members, the convenient timing of Woodruff’s revelation seemed suspicious, and they split from the mainstream church to practice polygamy in accordance with Smith’s teachings.

What happened to the splinter groups?
They have survived and, in some cases, thrived. Even though their lifestyle has been illegal for more than a century, there are now roughly three times as many practicing polygamists in North America than there were in 1890, divided among roughly a dozen different sects. The largest, and most notorious sect, is the Fundamentalist Church of Jesus Christ of Latter-day Saints (FLDS), which has some 10,000 members living in secretive communities scattered across Utah, the other mountain states, and Canada. Mainstream Mormons, who do not practice polygamy, denounce them as heretics.

How do other religions feel about polygamy?
Contrary to what you’ll often hear from modern defenders of “traditional marriage,” the sacred texts of Christianity, as well as those of the other major religions, are more than tolerant of polygamy. No less a figure than Abraham enjoyed the company of three wives, King David had an impressive 18, and David’s son King Solomon—whose eponymous Song is often read at weddings as a hymn to the joys of monogamy—somehow handled a household of 700 wives. The Jewish Talmud and the Islamic Koran tackle the issue more directly, saying that a man is allowed to take up to four wives, as long as he is able to provide for them and their offspring.

So why is it illegal in the U.S.?
That’s an intriguing question. The U.S. Constitution guarantees freedom of religion, and says nothing about how many wives a man might have, if all are consenting adults. Yet as law professor Jonathan Turley has pointed out, these protections are denied to polygamists on the constitutionally dubious grounds that having multiple wives just isn’t . . . well, normal. In its 1878 ruling that permitted states to outlaw polygamy, the Supreme Court sniffed that polygamy was “almost exclusively a feature of the life of Asiatic and African people,” and that it was “contrary to the spirit of Christianity”—the 700 wives of Solomon notwithstanding.

What about child abuse?
Opponents of polygamy say it’s no coincidence that in so many polygamous communities one finds very young girls being forced into marriage, and sex, with much older men. Child-rape, they argue, is what you inevitably get when you design a social structure in which men have more power than women. Of the 250 girls who lived at the Texas compound of the “Yearning for Zion’’ sect, authorities say, 60 percent were pregnant or had already had children. That’s no surprise, says Carmen Thompson, who left a polygamist sect after spending years as one man’s sixth wife. “The women don’t have any say as to what’s happening with their daughters in the first place,” Thompson says. “These decisions are made by the men, and often the men will trade their daughters with each other.”

In defense of polygamy
Not all polygamists live in sinister compounds under the heel of a tyrannical prophet. Many, like the fictional Henrickson family in HBO’s hit polygamy saga Big Love, lead discreet suburban lives and insist that the lifestyle is neither as bizarre nor as challenging as its critics maintain. According to a 2005 estimate by the pro-polygamy group Principle Voices, there are some 15,000 independent Mormon fundamentalists living in the Western U.S., Mexico, and Canada—people who believe in plural marriage and Joseph Smith’s other original teachings, but who live alongside normal monogamous families and eschew the authoritarian, cult-like practices of sects like the FLDS. In an interview with National Public Radio, Linda Kunz Green, one of the five wives of polygamist Tom Green, spoke to the joys and practicality of sharing her husband with four other women. “We have a very close, sister-like relationship with each other,” said Kunz Green of her co-wives, “and our children have often expressed that they enjoy having that many mothers to care for them and love them.”