" as the union between one man and one woman has been the universally-recognized understanding of marriage not only since America's founding but for millennia.”

—Tony Perkins, President of the Family Research Council, in response to the recent finding that gay people have a fundamental right to form families based upon legal marriage.

Having just co-authored a book where we survey the concept of marriage across many cultures, I’m calling B.S. on Mr. Perkins. He hasn’t got a clue what he’s talking about.

But Perkins isn’t alone in his vehement ignorance. A common refrain among those arguing against allowing same- marriage is that doing so would alter a long-standing trans-cultural definition of marriage. Rick Warren, the controversial evangelist Obama invited to speak at his inauguration, told Ann Curry in an NBC interview that, "For five thousand years, every single culture and every single religion has defined marriage as a man and a woman."

Hogwash.

In fact, the world is teeming with innumerable examples of “marriage” that would be unrecognizable to Warren and other so-called traditionalists.

Two-spirited ones (formerly known as berdache) were commonly found in many Amerindian cultures. They were either biological males who felt the presence of a female soul so strongly that they chose to live their lives as women or vice-versa, females who chose to live as men. Pedro de Magalhães de Gandovo described such people—whom he called Amazons—in 1576: "The [women] wear their hair cut in the same way as the men, and go to war with bows and arrows and pursue game, always in company with men; each has a woman to serve her, to whom she says she is married, and they treat each other and speak with each other as man and wife."

The Mosuo people of China practice a form of courtship and sexual interaction anthropologists have called “walking marriage,” which consists of women and men being completely free to sleep with whomever they like, children being cared for by the woman's family—her brothers assuming all paternal responsibility. Biological paternity is a non-issue. Every night is seen as an independent event, with no expectation of permanence or even continuity in amorous relationships.

Among the Canela people of Brazil, "Virginity loss is only the first step into full marriage for a woman." There are several other steps needed before the Canela society considers a couple to by truly married, including the young woman's gaining social acceptance through her service in a "festival men's society," which includes sequential sex with fifteen to twenty members (no pun intended) and "the mother in law's receipt of meat earned by the bride through extramarital sex" on a festival day.

Got that? Part of the marrying process is group sex followed by a gift to the mother-in-law-to-be of meat gained in exchange for gang-banging with men other than the husband-to-be.

Paging Pastor Warren!

For many societies, virginity is so unimportant there isn't even a word for the concept in their language.

In his book, Pleasures: The Sexual Lives of an Amazonian People, anthropologist Thomas Gregor reports that on his most recent visit to the Mehinaku, "the thirty-seven adults were conducting approximately 88 extramarital affairs." The figure is inexact, he tells us, because "opinions vary within the village as to who is having a genuine affair, and who is engaging in an occasional liaison." After some back-of-the-envelope calculating, Gregor concludes, "The villagers' taste for extramarital liaisons is limited primarily by social barriers, such as the incest taboo, and only secondarily by personal preference. In short, village men and women tend to have relations with each other unless they are specifically prohibited from doing so by the rules of their culture."

Similarly, Cacilda Jethá (co-author of Sex at Dawn) conducted a study of sexual behavior among villagers in rural Mozambique in 1990, finding that her study group of 140 men were involved with 87 women as wives, 252 other women as long-term lovers, and 226 additional women as occasional sexual partners, working out to an average of four on-going sexual relationships per man, in addition to whatever unreported casual encounters these men may have been having concurrently.

Among the Warao, another group living in the forests of Brazil, ordinary relations are periodically suspended and replaced by ritual relations, known as mamuse. During these festivities, adults are free to have sex with whomever they like. These relationships are considered to be highly honorable and to have a positive effect upon any children that might result.

In his fascinating New Yorker profile of the Pirahã of the upper Amazon, journalist John Colapinto reports that, "though [they] do not allow marriage outside their tribe, they have long kept their gene pool refreshed by permitting their women to sleep with outsiders."

As these representative examples clearly show, many qualities typically considered essential components of marriage in the contemporary western usage are anything but universal: sexual exclusivity, property exchange, paternal responsibility, the intention to stay together through thick (much less thin), even that the two partners are of different biological sexes -- none of these are expected in many of the relationships considered to be marriage in cultures around the world.

So when defenders of “traditional marriage” make their appeals to some universally-accepted notion of what marriage is, they're talking through their hats. No such institution exists, or ever has.