When a trend makes the cover of The Atlantic, you know it's really arrived. That's surely the case with the "sex recession," the term Kate Julian coined in a blockbuster article to describe a phenomenon that social scientists have been tracking and puzzling over for years now. Americans — and not just Americans — are having less sex than they used to.

A lot less sex. They're starting later and engaging with less frequency, with fewer people over a lifetime, and with less satisfaction. We may seem to the casual observer to be a sex-obsessed society, but it appears that impression is as accurate as someone's Instagram feed. And while there's some data to cheer about — a decline in teen pregnancy is surely a positive development, for example, as is the dramatic decline in new HIV infections — the overall picture is a depressing one, given how strongly correlated a positive sex life is with personal well-being.

What is the explanation for this sustained decline? Cultural conservatives will predictably indict the continuing echoes of the now-50-years-old sexual revolution that cheapened intimacy and disrupted the purportedly natural order of family-formation. Feminists need only gesture at any given week's headlines to bring their own indictment of violent male entitlement as the root cause. In both cases, the blame falls on changes in the culture.

The narrative satisfactions of such cultural explanations are obvious, which is why I'm instinctively inclined to look first for material explanations. And there are plenty on offer. Perhaps environmental pollutants are to blame for a drop in libido as they are plausibly to blame for a global drop in sperm count? Or perhaps it's the opposite, and the removal of lead from gasoline explains the drop in teen pregnancy as well as it explains the drop in teen criminality?

Economic explanations are also ready to hand. Partly as a consequence of the Great Recession, a whole cohort of young adults have lived with their parents at much higher rates and for much longer into their 20s (and even 30s) than previous generations. It's hard to build a stable relationship under such conditions. Meanwhile, those fortunate enough to have good-paying jobs increasingly feel married to them, leaving little time to explore the depths of human companionship.

Then there's technology, changing our habits and thereby our minds and brains. Are ubiquitous screens making us more distractible and depriving us of high-quality sleep? Has pornography-facilitated masturbation acted like a drug, blunting our drive to seek fulfilling erotic relationships? Is the sex recession a side effect of our widely-attested plague of anxiety and depression, or of the libido-dampening drugs prescribed to treat those conditions?

Sifting through and evaluating such a broad array of explanations would require copious research — and, as with much social science, a chief obstacle will likely be a lack of an adequate control group. But in this case, there's actually a natural control available: gay people.

Consider that list of material explanations. Environmental pollutants don't discriminate based on sexuality the way they do based on social class. The Great Recession hit gay people the same way it hit straight people, and they suffer the same high stress of the modern workplace. Smart phones should be disrupting everyone's sleep alike. If these are the culprits, then gay men and lesbians should be having just as much trouble forming lasting bonds as straight people.

What about the cultural explanations? Well, if the main effect of pornography is to provide a cheap and easy alternative to interacting with real people, then you'd expect rates of dating and couple-formation to decline for gays as well as straights. But if the primary impact of pornography is in some sense educational, teaching young adults what sex is or ought to be like, then that education might play out very differently among gay youngsters than it does for straights, since most straight porn is still made about women but for men.

Or consider the impact of apps like Tinder. Julian devotes extensive space in her article to the ways in which these apps fail to bring people together, even for casual intimacy, while crippling social spaces like bars where people used to go specifically to encounter new people. But then she notes in a parenthetical that the impact has been very different in the gay and lesbian community. There, the apps have been much more successful, and active dating is much more common. "This disparity raises the possibility that the sex recession may be a mostly heterosexual phenomenon," she says.

That's a very important aside. If it's true, then it strongly militates against the material explanations. But it also argues against cultural explanations, like kids being crippled by helicopter parenting or social media destroying young people's body image. And it complicates both simple narratives about the need for traditional sexual restrictions (gay couples get along fine without them) and about the inherent abusiveness of men (gay men are also men, and gay male relationships have to navigate a wide array of possible power differentials, just as straight relationships do).

What it suggests instead is that something has gone wrong in relations between the sexes, that men and women increasingly just do not know how to relate to each other in intimate situations. The feminists may well be right that it's straight men who have more adapting to do, but if the evidence is to be believed both straight men and straight women are suffering from the situation they're in and both have a powerful incentive to find a way out.

That complaint, of course, is not a new one either; there's a reason there are so many great songs about the inability to communicate. But if we've come to a such a pass that we can plausibly blame falling fertility in part on sheer fatigue at the prospect of even trying to partner up, we might actually have to figure out how to do something about it.