I turn 50 this month, and of the many surprises I've encountered in growing older, one has stood out: I get more hot, young guys now than I ever did in my youth. Weird.

I never thought I'd be single in middle age, but that's what happened when my long marriage fell apart. Suddenly single in my 40s, indoctrinated by a culture that says older women are reproductively worthless, I braced myself for loneliness. Turns out that was unnecessary, as young men were everywhere, vying for my attention.

At first, I thought this was some kind of fluke. But as I talked to older women friends about it, they shared similar stories. What the hell is going on? No one prepared us for this.

This epidemic of much-younger men seeking older women was widespread, yet no one was talking about it—at least not in a respectful or realistic way. If our story was told at all, it was in demeaning "cougar" tropes, with attractive older women presented as ridiculous exceptions to the unspoken rule that men prefer young women. I'd swallowed that lie, too, until my own life asserted a different truth.

As a journalist, I began asking questions. What was the sociology behind this? The history? The collective psychology? Was this a new phenomenon, and if so, what brought it about?

At first, I assumed it was all new—another quirky millennial thing. I figured the ubiquitousness of online porn had desensitized men and created a hunger for the taboo. Probably I was just a novelty fuck. Right?

Wrong.

The website Pornhub keeps meticulous statistics about what kind of porn people use. Their rankings for 2017 had "MILF" in third place, after "lesbian" and "hentai," with "step-mom" (a variant of "MILF") fourth, and "mom" (WTF?!) sixth.

So half of the world's most popular porn is about significantly older women. It isn't just me, and I'm not crazy. It is happening, worldwide. But I wanted to know why.

While my hypothesis about porn-related desensitization seemed to make sense, something about it didn't feel entirely accurate in real life. When I was with much-younger men, there was a tenderness there; a kindness that bordered, at times, on reverence, from them towards me. MILF porn didn't show that part—yet there it was.

I needed to understand what was driving this unique emotional bond my friends and I suddenly had with much-younger men. So I asked the men. Why did they want older women? What did they get out of it?

Time and time again, young men told me they preferred older women, but didn't know why. When they were able to articulate the reasons, novelty sex was never a factor. Instead, I got things like "they accept me as I am," or "they know what they want," or "they know who they are." In other words, even in a society such as ours, saturated with the objectification of young women, something in young men was still yearning for something more.

These guys weren't about a novelty fuck. They wanted to talk, to be validated, to connect. As I began allowing myself to explore these connections, I began to suspect that there was something ancient at play here. Something biological.

I turned to the work of primatologists for clues. In his 2013 book The Bonobo and the Atheist: The Search for Humanism Among the Primates, Frans de Waal talks about how male biologists have long told the world we are most closely related to chimpanzees, with whom we share 99.6 percent of our DNA, while hiding from the world that there is another ape with whom we also share 99.6 percent of our DNA: bonobos.

Humans, chimpanzees and bonobos all share a common extinct ancestor that walked the earth some 6.5 million years ago. But the matriarchal, polyamorous, bisexual, orgiastic bonobos were viewed as immoral by 20th-century white male biologists, whereas the patriarchal, violent behaviors of chimps were more consistent with who we collectively endeavored to be.

This made me wonder: Did young male bonobos or even chimpanzees mate with older females? If so, there would be a compelling biological explanation for what was happening to me.

Turns out, the answer was not just yes—but hell yes.

A 13-year-long study of chimpanzees, published in 2006 in the peer-reviewed journal Current Biology, concluded that "males prefer to mate with older females." Meanwhile, researchers from the Max Planck Institute for Evolutionary Anthropology found that among bonobos, mate selection was done entirely by females, and they chose the "most attractive" and virile (ie, young) males.

This means that in both of our closest primate relatives it is the norm, not the exception, for younger males to mate with older females. Which means it is probably the norm for us, too.

But this hasn't been an easy pill for male biologists to swallow. Researchers of the 2006 study grappled with it, theorizing: "Given that the human lineage evolved from a chimpanzee-like ancestor, [the study indicates] that male preference for youth is a derived human feature." I'm pretty sure they're blinded to our own nature, as so many of us are, by relatively recent cultural imperatives and social constructs.

The myth of male preference for younger females is a patriarchal social construct, and we should all stop accepting it as fact.

After all, our DNA, animal relatives and Pornhub all tell a very different story.

Alisa Valdes is a bestselling novelist, screenwriter and composer. A former staff writer for the Boston Globe and Los Angeles Times, she's now the arts and literature editor for the Weekly Alibi.