Chicago ? You could call it a real-life glimpse at sex and the city.

A new survey from the University of Chicago found that typical urban-dwellers spend much of their adult lives unmarried — either dating or single. And that has led to an elaborate network of “markets” in which these adults search for companionship and sex.

“On average, half your life is going to be in this single and dating state, and this is a big change from the 1950s,” said Edward Laumann, the project’s lead author and an expert in the sociology of sexuality.

The results, released Thursday, are part of the Chicago Health and Social Life Survey to be published this spring in the book “The Sexual Organization of the City.”

Laumann and his staff at the university examined how race and sexual orientation play a role in forming relationships, and how multiple sexual partners and jealousy also work into the equation.

Among other things, they found that, between the ages of 18 and 59, those surveyed cohabited an average of nearly four years and were married about 18. The rest of the time — an average of about 19 years — they were dating or alone, with no steady companion.

Researchers interviewed 2,114 people in the Chicago area between 1995 and 1997, as well as police officers, clergy and social workers. They also took an in-depth look at neighborhoods with predominantly black, Hispanic and gay populations.

Playing the markets

Divorce was, of course, one of the big reasons so many people were single. But so was the fact that many young people are putting off marriage — sometimes because of school, but also because many are approaching the institution of marriage more warily.

That’s true for Nikhil Bagadia, a 24-year-old Chicagoan who has been dating a woman for about four months but wants to take things slowly.

“I think a lot of people jump into marriage before they should,” said Bagadia, who’s in pharmaceutical sales.

When looking for a partner, researchers found that people use two basic markets — “transactional” and “relational.” Bagadia prefers relational encounters, often facilitated by family, friends or even fellow churchgoers. He met his girlfriend through some of his college buddies.

Transactional relationships are relatively uncommitted and often meant to be short-term. They happen when two people who don’t know one another meet in a bar, health club or other public place.

Laumann and his colleagues said markets also often were defined by racial group, neighborhood and sexual orientation.

In Hispanic neighborhoods, for instance, family, friends and the church played a more important role in forming partnerships among those surveyed. Young, upper-income people on the city’s north side were more likely to meet their partners at school or work.

Researchers said the markets also operated differently for men and women.

Women surveyed were, for instance, less likely to meet a partner through work, church or other “embedded institutions” as they got older — making it more difficult to find someone. Laumann said that might be due, in part, to the fact that men in their 40s often sought women who were at least five to eight years younger.

Meanwhile, many gay men in the survey were largely focused on transactional relationships, while lesbians were far more interested in relational connections.

New sexual revolution?

Researchers also addressed the issues of multiple partners and jealousy.

Overall, 23 percent of men and 31 percent of women said they experienced jealous conflict at some point during their relationships. And researchers found that cohabitation resulted in more jealousy — and physical violence — than it did among married couples.

Men were more likely than women to have more than one sexual partner. Among those surveyed, 20 percent of men and 6 percent of women said they’d had sex with at least one other person during their most recent relationship.

“What’s going on now is making the sexual revolution of the ’60s and ’70s pale in comparison,” said Eli Coleman, director of the Program in Human Sexuality at the University of Minnesota. He called Laumann’s work the most comprehensive since that of acclaimed researcher Alfred Kinsey, who surveyed people about sex in the 1940s.

Still, Laumann and his staff found that social services, the church and law enforcement have been slow to address this latest sexual revolution.

For instance, they found no shelters in any of the studied communities for gay domestic abuse victims.

And most churches they examined were not good at “giving guidance about how you manage a stable but nonmarried relationship,” Laumann said.

“It’s not approved. It’s not talked about,” he said. “Or they just look the other way.”