The connection between marriage equality and cell phones is not immediately apparent, but Justice Samuel Alito made the link during a Supreme Court argument on California’s Proposition 8 last month.

As Justice Alito said to Solicitor General of the United States Donald Verrilli:

Traditional marriage has been around for thousands of years. Same-sex marriage is very new. There isn’t a lot of data about its effect. And it may turn out to be a good thing; it may turn out not to be a good thing, as the supporters of Proposition 8 apparently believe. But you want us to step in and render a decision based on an assessment of the effects of this institution which is newer than cell phones or the Internet?

From his line of questioning, Justice Alito clearly seemed worried about replacing a venerable institution with a “newfangled” one that could turn out to be bad for society. And he wasn’t the only one with concerns. Cardinal Timothy Dolan, head of the U.S. Conference of Catholic Bishops, speaks for many Catholic leaders when he insists that marriage between a man and a woman is God’s intention for humankind. The Mormon Church holds a similar view, as do thousands of evangelicals and Orthodox rabbis. Even some young conservatives, unlike most of their contemporaries, are standing up for their belief that “traditional marriage” is inherently natural and good.

But here’s the problem: The notion of traditional marriage that these conservatives are so vigorously defending is not historically accurate. Pundit Bill Kristol recently fell into this trap when he complained that supporters of marriage equality want to overthrow “thousands of years of history and what the great religions teach” about marriage.

In actuality, traditional marriage—as it existed centuries ago—is not worth defending.

Let’s start with concubines—also known as mistresses—who were owned by husbands in ancient cultures and are mentioned without disapproval throughout the Hebrew Bible. Then there’s the practice of polygamy, which was the norm in biblical times. Back then, tradition forced rape victims to marry their rapist. Tradition also called for victorious soldiers to make female war prisoners their wives and concubines.

In the Middle Ages, marriages were arranged for political and financial reasons, and girls could be forced to marry when they were as young as 12 years old. British Common Law held a man to be “lord and master” of his wife who was subject to “domestic chastisement.” Wife beating was legal and common in England until the late 1800s.

In colonial America, wife beating was illegal, but marriage equaled patriarchy. A wife had no legal rights or existence apart from her husband. Any money or property she inherited belonged to him. Their children were his as well. Wife abuse was not uncommon.

In 1864 a North Carolina court heard the case of a woman abused by her husband because she had called him names. The court ruled that:

A husband is responsible for the acts of his wife, and he is required to govern his household, and for that purpose the law permits him to use towards his wife such a degree of force as is necessary to control an unruly temper and make her behave herself; and unless some permanent injury be inflicted, or there be an excess of violence, or such a degree of cruelty as shows that it is inflicted to gratify his own bad passions, the law will not invade the domestic forum, or go behind the curtain.

It wasn’t until the 20th century—when women fought for and won the right to vote, to sign contracts on their own, to obtain financial credit, to have access to contraception, and more—that these earlier notions of traditional marriage began to crumble, and something resembling the institution we recognize today began to emerge.

But each of the advances for women’s equality was fought by forces that considered them an invasion of the sacred private realm of the home and an assault on the family. Even so, these advances became part of law and culture and are now the norm. In fact, they are embedded in the institution that conservatives are now so fiercely defending.

Marriage has always been dynamic. For the most part, its evolution has been positive. Marriage today is far more mutually supportive, egalitarian, and secure for children than it was centuries ago. Take heart, conservatives. The institution of marriage does change and adapt over the years, and that is what makes it endure.

Sally Steenland is Director of the Faith and Progressive Policy Initiative at the Center for American Progress. Steenland, a best-selling author, former newspaper columnist, and teacher, explores the role of religion and values in the public sphere.