The science of same-sex marriage: with the two-year anniversary of same-sex marriage in Massachusetts comes a flood of studies, books, and research papers on the benefits of marriage for gay couples and the harm caused by denying it.

Chuck Colbert was already angry about not being able to marry his longtime partner, Troy Golladay. But when the Vatican released a statement in 2003 calling same-sex unions "gravely immoral," Colbert, then still a practicing Roman Catholic, saw his psychological and physical health decline. "It was chewing me up inside," he says. "I was very sluggish. I battled with either depression or seasonal affective disorder. I was nasty to other people. It was just poisonous."

That all changed after Colbert, 51, and Golladay, 38, were issued a marriage hcense just after midnight on May 17, 2004, in Cambridge--the first municipality in Massachusetts to issue licenses to same-sex couples. Soon Colbert and Golladay were in better mental and physical health, and the marriage allowed Colbert to get health insurance through Golladay's employer. "We now have a sense of security and place that we didn't have before," says Golladay, a marketing manager with the card company Hallmark.

The experience shared by Colbert and Golladay--mirrored by that of gay and lesbian couples around the world--hasn't gone unnoticed by academic and scientific researchers. Numerous scholarly books and research papers have been published in recent months demonstrating how allowing same-sex couples to marry produces positive health benefits for the couples--and how denying it has the opposite effect.

Researcher Darren R. Spedale spent two years in Denmark on a Fulbright scholarship researching same-sex partnerships, which have been legally recognized there since 1989 and provide most of the benefits of marriage. His new book, Gay Marriage: For Better or for Worse? What We've Learned From the Evidence, coauthored by Yale Law School professor William N. Eskridge Jr., is one of the first to present empirical evidence about the effects of legalized same-sex partnerships. "What we found is the legal benefit of marriage leads to an emotional benefit of security," Spedale says.

Public recognition also brought many couples out of the closet, says Eskridge. "The couples were more out to their families, their communities, their coworkers. And psychological literature suggests that how open you are, how comfortable you feel in your community, is strongly linked to having a better self-image and other health effects."

Right-wing religious leaders like to argue that allowing gay couples te marry will lead to an erosion of the institution of marriage, Eskridge adds. But in Denmark, among heterosexuals, rates of divorce and out-of-wedlock births have actually gone down since 1989, while marriage rates have gone up.

Eskridge and Spedale also found that legal recognition of same-sex unions has an impact on public health. Countries that recognize same-sex couples have had lower rates of sexually transmitted diseases, including AIDS. "When we asked couples how being married has affected their lives, a common answer was that it made them monogamous," says Spedale. "But even those couples who are nonmonogamous report that they are more careful with their outside activities. They want to protect their partner and don't want te bring anything home."

Stuart Gaffney married his partner of 19 years, John Lewis, in San Francisco after Mayor Gavin Newsom began issuing marriage licenses to gays in February 2004. "For the first time in our lives, we experienced being treated equally under the law," says the 43-year-old Gaffney, a policy analyst at the University of California, San Francisco's Center for AIDS Prevention Studies. "We literally felt years of shame lifting with the realization that now we were being treated as equals. It was a utopian moment for us."

But after a court ruled their marriage invalid--along with all of the San Francisco same-sex marriages--a few months later, "we felt that sense of shame placed right back upon us," Gaffney says.

In places where same-sex marriage is denied or banned, gay couples can feel "minority stress," says Ellen D.B. Riggle, associate professor of political science and associate director of the women's studies program at the University of Kentucky. "With minority stress, most people learn coping mechanisms, which can include drinking, substance abuse, and depression," she says.

Anthropologist Gilbert Herdt and psychiatrist Robert Kertzner have found that to be true. They are the authors of "I Do, But I Can't: The Impact of Marriage Denial on the Mental Health and Sexual Citizenship of Lesbians and Gay Men in the United States." The peer-reviewed study was published in the March 2006 issue of Sexuality Research and Social Policy, the journal of San Francisco State University's National Sexuality Research Center, where Herdt serves as director. It shows that in spite of their ability to create alternative family structures, gays and lesbians suffer hindered mental health and well-being as a result of being denied the right to marry.

And it can lead to what Herdt and Kertzner call "relationship ambiguity." "These couples are at greater risk of ending the relationship, particularly during hard times," says Kertzner, an associate clinical professor of psychiatry at UCSF who is also an adjunct associate research scientist in Columbia University's psychiatry department. "There's a vicious cycle of marriage denial," adds Herdt. "The stereotype is that gays are promiscuous and abnormal and therefore unfit to marry and raise children. But because gays are denied the right to marry, they are seen as being abnormal."

Even the debate over providing marriage rights--with its caustic rhetoric--can have an impact on the well-being of gays and straights alike. "The current debate features negative stereotypes, intentionally demeaning and delegitimizing rhetoric, and the institutionalization of discriminatory policies," according to a paper cowritten by Riggle. "While the target of the rhetoric and policies is same-sex couples, one set of citizens cannot be publicly demeaned without demeaning the entire citizenry and creating divisions within a society."

That's exactly what Kevin Alderson, coauthor of Same-Sex Marriage: The Personal and the Political, is afraid will happen again in Canada. As assistant professor of applied psychology at the University of Calgary, he is concerned over newly elected prime minister Stephen Harper of the Conservative Party, who has promised to revisit the country's recent legalization of same-sex marriage. "When the Conservatives took power earlier this year, I was on some level devastated," Alderson says. "I knew we would suffer the backlash."

But Canada's gay couples are not likely to lose their right to marry, and Alderson believes that studies spurred by marriage equality can act as a guiding light, especially in the United States. "Researchers will be able to establish that married couples in Massachusetts are doing better than those in other states," Alderson says. "We have to go beyond 'rah-rah' activism and look to research to show that same-sex marriage is a viable institution that does not detract from heterosexual marriage."

Indeed, Colbert and Golladay say they can provide the proof. "The intermingling of our lives legally and financially made us think differently," says Colbert, who is now a Reform Jew. "It gave us a heightened awareness of the responsibility we have toward each other. And it gives us a wonderful feeling of being part of the Commonwealth of Massachusetts and the common good."

Kuhr is editor at large for In Newsweekly.

RELATED ARTICLE: Are we getting married?

Among the places where same-sex couples have equal marriage rights, the number of marriages has varied widely

United States

5,994 In Massachusetts in 2004, after same-sex marriage became legal there on May 17

Canada

3,000 Estimated number of same-sex marriages from June 2003, when Ontario first al lowed them, through November 2004; federal legislation was passed in July 2005

Spain

1,000 Estimated marriages from June 2005 legislative legalization to March 2, 2006

Belgium

2,442 Total number of marriages from legalization in January 2003 through June 2005

The Netherlands

8,127 Total number of marriages from legalization in September 2000 through 2005