This is part of a series of stories examining the cultural, social and political currents swirling around marriage.
In ancient Greece and Rome, marriage was primarily a way for the upper class to pass down family property.
In early American Colonial times, a man and woman were considered married if they simply said they were.
And it wasn't until about a century ago that the practice of marrying for romantic love became widespread.
In the national debate over gay marriage, supporters say marriage is about love and commitment between two people, and that to deny gay men and lesbians the public sanction and legal benefits of marriage violates their civil rights.
Many opponents argue that legalizing gay marriage amounts to disavowing a cornerstone of Western society — an institution they say has historically been between one man and one woman, and designed primarily for child-rearing.
A look at the history of marriage in Western civilization, especially since the rise of Christianity, shows that it has, indeed, largely been between a man and a woman and designed, in large part, for the production of children. At the same time, it's an institution that has constantly evolved in response to changing social and political forces.
"Marriage is not an institution that's etched in stone," said Steven Mintz, a University of Houston professor who specializes in family history. "Whenever people talk about traditional marriage or traditional families, historians throw up their hands, because we say: 'When and where?' "
Marriage has existed since the earliest civilizations, with records of ancient Mesopotamia showing evidence of ceremonies and contracts. The institution likely has endured over the centuries because it fulfilled so many social and personal functions: It offered a structure that determined how property was to be handed down, how labor was to be divided, how children were to be cared for, how companionship would be assured.
Different cultures in different times have practiced many forms of marriage. The ancient Hebrews, for instance, practiced polygamy — a form of marriage once widespread among cultures worldwide. Until the 19th century, some Native American cultures allowed two men to essentially marry, provided one underwent a ritual that resulted in his being considered a crossed-gender or mixed-gender person.
"If you're talking about the history of the world and not just the last two centuries, the proportion of the world populated by monogamous households were a tiny, tiny portion — just Western Europe and little settlements in North America," said Nancy Cott, professor of history at Harvard University.
"What we talk about as marriage — monogamy between a man and a woman that's supposed to be lifelong, unless something goes wrong, and where there's sexual faithfulness — that's a Christian idea."
Indeed, Christianity has provided the foundation of what Western culture understands marriage to be today. It is largely this Christian tradition — the idea of marriage between one man and one woman as being what God intended — that is at odds with the idea of gay marriage.
Yet even within this Christian context, historians say, the purposes and functions of marriage have constantly evolved.
In America, for example, founded on Judeo-Christian values, people have debated everything from whether people of different races could marry, to the role of men and women in marriage.
Throughout this country's history, says Mintz, "Americans have repeatedly contested what marriage is all about and what form it should take."
A matter of class, contract
In ancient Greece and Rome, the foundations of Western civilization, marriage was regarded as a civil contract, conducted mainly by the propertied class to perpetuate the family line and produce legitimate heirs.
The state did not get involved — marriages were considered a private contract arranged between a bridegroom and the father of a bride, and could be terminated at any time by either partner.
Though marriage was a heterosexual union, and a person could have only one spouse, that didn't preclude married men from having concubines who might bear their illegitimate children. It was also acceptable for men — married or not — to have sexual relationships with other males.
In the ancient Greek city of Thebes, for instance, one of its most celebrated military forces was the Sacred Theban Band, which was said to have been formed of 150 pairs of male lovers, some of whom probably had wives, said Lawrence Bliquez, a classics professor at the University of Washington.
Though homosexuality was practiced, ancient Greeks and Romans didn't think of it as either innate or exclusive of relationships with people of the opposite gender. Thus, exclusive same-sex relationships — in which men would not marry, produce offspring and perpetuate the family line — were probably unacceptable, said Bliquez.
Rise of the church
It wasn't until the Roman Empire collapsed, around the 5th century, that the Catholic Church — for centuries the only Christian church — further extended its influence. The church elevated marriage from a civil contract to a sacred union, forming the basis of marriage laws in most Western countries.
In the 5th century, the church began clearly articulating the values and practices the faithful were expected to apply to their daily lives, including marriage. Referring to biblical passages, church leaders spoke of marriage as an unbreakable covenant between a man and a woman made "one flesh" by God.
They saw a passage from the Book of Ephesians, equating the love of a husband for his wife to that of Christ's love for his church, as a basis for the sacredness of marriage.
Still, marriages in the early Middle Ages, between the years 400 and 800, were "pretty ad hoc," said Theresa Earenfight, assistant professor of history at Seattle University. Fledgling states "couldn't run themselves then, much less manage marriage."
The church, too, had not yet developed a strong central infrastructure, so marriages were largely celebrated according to existing local customs. The church considered couples married if they simply gave their consent to each other and consummated the relationship.
From about 800 to 1200, as both church and states grew in power, the Catholic Church began enforcing more of its rules on marriage — prohibiting marriage between close relatives, for example, and stipulating that marriage could only be between a willing man and woman.
Church law and royal law worked together to form increasingly detailed laws surrounding marriage — such as rules for inheritance and dowries. Divorces became harder to obtain. In 1215, marriage was officially declared one of the church's seven sacraments, holy rites that include baptism and penance. After about 1200, the distinctions between church and state weddings began to blur, with most Christians getting married in church, and most states recognizing church marriages. In the mid-1500s, churches required marriages to be performed in public, by a church representative and before two witnesses.
But even as a sacrament, marriage still had its earthly purposes.
For the ruling class in Europe, for example, it remained a way to forge political alliances. In 1540, for instance, King Henry VIII of England, believing he needed an ally to repel threats from France, married Anne of Cleves, whose brother led the Protestants in western Germany. Six months later, after a French threat failed to materialize, the king had the marriage annulled.
For both the upper and aspiring classes, marriage was a way to gain capital — mainly through dowries. And for lower-class families, marriage could increase property holdings by merging one family's land with a neighbor's.
Beginning around the 16th century, the primary purpose of marriage shifted, to that of building the family as a labor force. At the same time, the Protestant Reformation brought about the idea that marriage should focus more on child-rearing.
Critics of the Catholic Church said its emphasis on chastity and a celibate clergy didn't place enough importance on marriage and the raising of children, said Mintz, the University of Houston historian.
The Reformation raised the idea of families as "little churches" that would educate children — an ideal that wouldn't flourish in practice until two centuries later.
Love and marriage
Around the 18th century, the Enlightenment movement took hold, shaped by intellectuals who placed greater value on human logic and reason than on faith and church doctrine.
As freedom and personal fulfillment became more important, people began thinking marriage should be for love — not arranged, but rather, entered into freely.
That isn't to say earlier marriages didn't provide comfort and companionship — many people did, indeed, come to love their spouses.
"But people thought it was crazy to marry for such a fragile reason as love," said Stephanie Coontz, a historian with The Evergreen State College and co-chairwoman of the Council on Contemporary Families, a nonpartisan group of family researchers.
"If love could grow out of it, that was wonderful. But that was gravy."
It wasn't until about a century ago that that notion of marrying for romantic love became widespread practice.
Married in America
In the United States, as in Europe, how and why people married, who was allowed to marry, and how marriages functioned has also continually evolved.
In early American Colonial days, when there were few courts or churches, marriages were informal by necessity — many got married by living together and declaring themselves husband and wife. Such common-law marriages are still allowed in 11 states and the District of Columbia, said Mintz, of the University of Houston.
Before the Civil War, slaves were considered property and thus could not marry legally, though many slaves held their own ceremonies.
After the war, many states banned interracial marriages. Also, in the early 1900s, when anti-Asian sentiment was high, a national law said women who married Asians — even U.S.-born Asians — lost their citizenship. The U.S. Supreme Court declared such laws unconstitutional in 1967.
The role of men and women in marriage also has evolved — from husband as legal head of household, to the now widespread notion that marriage should be between equals.
In Colonial times, marriage was "more a work unit than anything else," said David Popenoe, professor of sociology at Rutgers University and co-director of its National Marriage Project, a nonpartisan institute aimed at strengthening marriage through research. "As in any work unit, the idea was you needed a boss to make it work efficiently. So the men were the boss."
Coontz, The Evergreen State College professor, places the current debate over gay marriage in the context of Americans having "already turned our backs on thousands of years of history when we said women should be equal to men, marriage should be for love, and kids should have the right to choose who they want to marry."
She sees the debate as "really a question of which part of the history do we want to keep and which do we want to discard. We've already discarded a lot of it."
Popenoe agrees marriage has evolved but believes its most important function should be to provide a stable environment for raising children.
Research has shown, he said, that growing up with both a mother and a father is beneficial to children and thus to society.
Fewer marriages ahead?
Some scholars believe another evolution in marriage may be taking place in Western countries.
After the purpose of marriage became primarily love and happiness, people who fell out of love could — and increasingly did — get divorced. When marriage is driven by love, and divorce is an option, the breakup rate is high.
But "the most notable change in marriage in recent years is not divorce, but the decline in the number of marriages," Mintz said.
Indeed, the marriage rate in the U.S. is half what it was when it peaked right after World War II.
To some extent, Mintz sees marriage in Western cultures returning to a kind of "pre-modern pattern" where upper-class people marry to protect their holdings while many others don't marry at all.
"There's kind of an irony that we as a society are fixating on marriage," he said, "when in fact much of what is going on is happening outside of marriage."
Janet I. Tu: 206-464-2272 or firstname.lastname@example.org