My parents are incapable of getting over the idea that the vast majority of my friends are either single or dating one person exclusively. In their day, apparently, it was much more common to date many people casually, which would sometimes lead to a state of "going steady." Among today's college crowd, there is almost no distinction between dating and "going steady."

Of course, this doesn't mean that no one dates casually anymore, but social mores certainly seem to discourage it. My experience with the dating scene has left me with the impression that if a relationship has progressed past the initial few getting-to-know-each-other dates, it is considered cheating for one partner to date another.

This drastic shift in attitudes from my parents' generation to ours stems from the confluence of two factors: the sexual revolution and the subsequent AIDS epidemic. The social scene of my parents' generation (late 1950s to late 1960s) may have been characterized by casual dating, but it also seemed to emphasize the postponement of intimacy, especially sex. Those who were caught up in the counter-culture movement of the late 1960s rebelled against these values, among others. Suddenly, having multiple dates meant having multiple sexual partners. Though other social factors are certainly at work, it's telling that the birth rate among unmarried women 15 to 19 years old increased from 12.6 to 42.5 live births per 1000 women between 1950 and 1990.

In the wake of the sexual revolution came AIDS. Once the realization had sunk into the human psyche that sex can be life-threatening, the nature of relationships in our society had to change. And there were two main roads our culture could follow. The first was to return to the 1950s notion of postponed intimacy. The second was to retain sex as part of the dating scene, but to make relationships monogamous. And this is what appears to have happened. Quite simply, the behavior of the most technologically advanced and socially complex civilization the world has ever known has been forced towards emotional and sexual exclusiveness by the most basic of human needs--survival.

This isn't a new phenomenon. Sexual habits are, of course, fundamental to a society's success. The very reason most societies place value on monogamy is that it helps ensure survival. Polygamy tends to lead to jealousies and quarrels--which are disruptive and can even become deadly--and is probably not conducive to effective child-rearing. It seems reasonable that the institution of marriage evolved in response to this reality. The small communities which characterized early human history faced enough challenges without infighting over women.

What is significant about the effect of the AIDS virus is that for perhaps the first time, American society in all its complexity is shifting its habits not because of the political or economic realities of the modern world, but rather because the way we behave has suddenly imposed a very real and immediate threat upon our lives. Even if a cure for HIV were developed tomorrow, in my mind sex and romance will always be inextricably tied to the need for caution and restraint, due to ravages of a disease that is younger than I am.

But it is entirely possible that the tragedy of AIDS will have one positive result. In my parents' generation, dating was more casual, but the institute of marriage was far stronger than it is today. In the end, it is conceivable that the trend toward monogamy engendered by AIDS could lead to a drop in the still-rising percentage of marriages that result in divorce. How ironic that this scourge may help to heal our social fabric.

David H. Goldbrenner's column appears on alternate Fridays.