Psychology Today advocates multiple partners and open marriages and offers “evidence” that monogamy isn’t possible. Comparing man to animals is weird to me—we’re supposed to be separated out by reason and morality, right? —The Good Wife, Austin, Texas

Psychology Today, ever on the cutting edge, has had monogamy in its crosshairs lately. A casual search turned up at least nine articles on the subject in the last year. Here’s a representative quote, from “The Truth About Polyamory” by Deborah Taj Anapol:

“Our cultural obsession with monogamy is going the same way as prohibition, slavery, the gold standard, and mandatory military service. In other words, while serial monogamy is more popular than ever, lifelong monogamy is pretty much obsolete, and for better or worse, polyamory is catching on.”

Let’s break this down:

Monogamy is on a par with prohibition, slavery, etc. Spare me. Polyamory is catching on. Depends how we define the term. If strictly, show me your cites, lady. If more liberally, we can talk. More below. Serial monogamy is in, lifelong monogamy is out. True beyond dispute. However, we need to clarify what we mean. Time for the straight dope.

Let’s start with those investigations of animal mating habits you take issue with. It’s often said 9 percent or some other low proportion of mammals is monogamous. So? A puppy reaches maturity in a year; a human newborn needs 11 to 12 years. There’s an explanation for monogamy right there.

Except it doesn’t hold up. Among chimpanzees, the species most closely related to us, the young reach maturity in 8 to 15 years, comparable to humans. But chimps mate promiscuously and never pair off. Although the young remain with their mothers, there’s otherwise minimal family structure. Alpha males dominate and have sex more often than males farther back in the alphabet, but they don’t have harems to organize and defend.

My point is, there’s nothing in our biology that demands monogamy. Sure, it has practical advantages. For humans, rearing the young is a more labor- and resource-intensive process than for chimps, who don’t have college tuition to contend with. But I’ll bet we could come up with some free-love it-takes-a-village kibbutz thing if we put our minds to it.

A lot of Psychology Today contributors think that we’ve arrived at an advanced state of civilization, and we’d be happier if we abandoned the impossible dream of happy lifetime pairing and tried something else. The question is whether we’re actually doing so in significant numbers. Answer: Of course we are. It’s just not called polyamory, or some other trendy term. It’s called divorce.

Let’s look at monogamy alternatives, from least to most common (I’ll ignore celibacy):

Open marriage—that is, a married couple who expressly allow each other to have other sex partners. I don’t doubt there are secure, stable individuals who can handle this long-term without tears. But not a lot. PT contributor Michael Castleman cites unnamed “sexologists” as saying 1 percent of married couples are “committed to occasional non-monogamy,” with “another percent or two ‘curious’ enough to visit sex or swing clubs.” Self-report of sexual activity is notoriously unreliable, but never mind. We’ll say 1 to 3 percent.

Adultery. American men currently have a 28 percent likelihood of being unfaithful to a partner by the time they reach age 60, and women a 15 percent chance. Possibly this is more than in the past, but the change isn’t dramatic.

Polyamory. In its purest form, this term is apparently used to mean having sustained, emotionally intimate sexual relationships with multiple partners who all understand they’re sharing. Nothing persuades me this is common on my planet. However, if we expand the definition to cover the behavior of unmarried individuals who juggle multiple lovers at times, the number obliged to fess up would surely be impressively large. This provides useful context for our last category.

Divorce. Here we arrive at the heart of the matter. As of now, how many Americans will experience lifetime monogamy? Answer: less than half. As of 2011 for every 6.8 marriages there were 3.6 divorces—a 53 percent rate. This is significantly more than just 10 years earlier, when the divorce rate was 49 percent.

Even more striking: According to Pew Research, in 1968 the number of unmarried U.S. adults (including those widowed, divorced, and never legally married) was just 28 percent. As of 2010, it was 49 percent.

In other words, half of us are single and playing the field, and a sizable fraction of the other half will eventually shed their partners and join the fray. Conclusion: Lifetime monogamy has ceased to be the default American condition, even if the time of first marriage is when we start the clock. —Cecil Adams