The recent surge in stories about young men abandoning higher education — college women outnumber men 3 to 2 — may have surprised a few headline writers, but the graffiti about the decline of men and boys has been on the wall for decades.

We’re merely seeing the culmination of 50 years of feminist advances combined with economic shifts that have left men unemployed and socially sidelined. Early warning signs were clear in the 1990s when men began organizing — a disconsonant concept, I admit — around grievances about divorce and subsequent custody battles. Fathers were feeling increasingly displaced by child-custody arrangements that often “repurposed” fathers as weekend visitors in their children’s lives.

“Trickle down” may not work in economics but it sure does in society and culture. The lesser regard for men’s interests was also manifesting among younger-aged males as girl power seized the public imagination. School curriculums were being adjusted to become more go-girl and less boy-centric.

In practice, this meant a growing intolerance toward boy behavior in general; complaints that they couldn’t sit still in school like the girls; and an epidemic of ADHD diagnoses and medication of children, mostly of boys (11.7% male to 5.7% female, according to the Centers for Disease Control and Prevention). Just ask any mom with a son born in the past 25 to 30 years: Boys became suspect, wrong from the start. Or, as I began my 2008 book, “Save the Males,” quoting a then-10-year-old boy: “Men bad, women good.”

School reading lists were suddenly missing books about heroes, chivalry, knights and other such symbols of boyhood fantasy, while girls were embracing female heroes (we don’t say “heroine” anymore) and fantasizing about becoming Supreme Court justices and fighter pilots. “Girl power,” first introduced in 1991 by punk band Bikini Kill, had become a household phrase by the time Mary Pipher’s “Reviving Ophelia: Saving the Selves of Adolescent Girls” became a bestseller. Pipher, a psychologist, highlighted the challenges modern girls and teens faced with both a “lookist,” girl-destroying culture and culture shot through with sexual violence, resulting in eating disorders and suicide attempts.

While correcting the cultural deficits and opportunities for girls was a grand mission that wouldn’t have gained traction without the relentless activism of feminist-minded women — and men — we sometimes veered into zero-sum territory. If girls were to succeed, boys would sometimes lose and, well, too bad. Hadn’t they had the upper hand long enough? This was no one’s stated aim, I’m pretty sure, but it became difficult to ignore trends aimed at diminishing the value of men and, collaterally, boys.

Sperm banks began flourishing in the 1980s. Financially secure women were able to buy home self-insemination kits at the same time they began outpacing men in medical and law schools. Recent figures show that the global market for frozen sperm, which theUnited States leads, will reach close to $5 billion by 2025. Who needs a real daddy?

Apparently, nobody, if you bought into a 1999 study published in American Psychologist titled, “Deconstructing the Essential Father,” in which researchers sought to prove that fathers aren’t necessary. Their admitted mission, which included studying “cross-species,” was to shift family policies away from heterosexual families toward alternative family structures.

It is little wonder that fathers became unnerved by such advanced social research. If fathers aren’t essential, then how are boys to imagine themselves? Fathers are essential to daughters, too, but boys need fathers to show them how to become men. Say what you will, but the strongest force of nature is imitation. Monkey see, monkey do. Ever watch a little boy walking alongside his father, trying his best to match his stride and swing his arms just so? This dependence only deepens when a young man tries to figure out how to organize his life.

By 2000, the first books appeared cataloguing feminism’s unintended consequences. While girls were catching the waves, boys were treading water. Among them were “The War on Boys,” by Christina Hoff Sommers, a senior fellow at the American Enterprise Institute, and “Raising Cain: Protecting the Emotional Life of Boys,” by child psychologists Michael Thompson and Dan Kindlon. By 2007, Kindlon had written another book: “Alpha Girls: Understanding the New American Girl and How She Is Changing the World,” based on his observations of his own daughters and statistics such as the ones that began this column.

Girls born since 1980, he said, are different from their mothers. They suffer no delusion that they are the second sex or, laughably, the weaker sex. They’re hands-on-hips Superwomen wondering, as New York Times writer Maureen Dowd did in her 2005 book, “Are Men Necessary?,” which Hanna Rosin answered in 2014 with her book, “The End of Men.”

Given the above, why would young men bother going to the trouble and expense of college? And they won’t if we don’t start making our boys feel as valuable as our girls. As Thompson recently noted, “We can’t have a country of women in white-collar jobs and men in blue-collar jobs. That’s not going to be good for this society.”

The karmic irony is that women shopping for frozen sperm only want the highest quality, college-educated kind. If trends continue, we may be joining the ivory-billed woodpecker among the extinct.