Childlessness is nothing new — for as long as we’ve had parents, we’ve had people who are not parents. Across centuries and cultures, at least 10 percent of women never have children, writes Elizabeth Gilbert.

But it is relatively new to have a cohort of people who are deliberate, outspoken, and even proud about being childless — or, as we prefer to say, childfree. We nonparents have traditionally been a quiet minority. And we’re still a minority — albeit a growing one, now about 20 percent in both the U.S. and the U.K. — but we’re no longer so quiet.

In 2010, the childfree started making some real noise. Get used to it; you’ll be hearing a lot more racket from us in the future. Here are some of the cultural signals and media moments that have rung out during the past year, putting the childfree lifestyle in the spotlight as never before.

Oprah’s having a baby! (No, not that kind)

Oprah Winfrey is probably the most powerful and influential childfree person on the planet. She doesn’t harp(o) on her decision to skip motherhood, but in a December 2010 interview with Barbara Walters, she said, “I have not one regret about not having children.” As she explained, “I could not have had this life and lived it with the level of intensity that is required to do this show the way it’s done. I’d be one of those people that their kid’s coming and saying, ‘Mom, you’ve neglected me.’”

Oprah has found other outlets for her nurturing instincts — like students at the school she set up in South Africa a few years ago. “These girls are like my children,” she said. “That’s not just rhetoric for me. I take their futures and the possibility for what their futures hold very seriously.” And now she’s channeling some of that maternal intensity toward the Oprah Winfrey Network, which launches on Jan. 1. “I look at this launch as the birthing of a baby,” she said. “I’m about as calm as a person who’s about to give birth to such a humongous baby can be.”

Watch Oprah talking to Barbara about her choice not to have kids (starting at 7:29):

You’ve come a long way, babyless

The childfree got another high-profile (albeit fictional) spokeswoman this year in Carrie Bradshaw, who defends her decision not to become a mom in Sex and the City 2. “We both love kids, but it’s just not who we are,” Carrie says of herself and her husband.

Julia Roberts played the happily childfree writer Elizabeth Gilbert in the movie Eat Pray Love this summer, even as Gilbert came out with the new book Committed, in which she discusses at length her decision to forgo parenthood and her delight at being a member of the “Auntie Brigade.”

Cameron Diaz talked this year about her happily childfree state, after saying last year, “We don’t need any more kids. We have plenty of people on this planet.”

Marie Claire magazine rounded up more childfree celebs, including Renée Zellweger, Eva Mendes, Janeane Garofalo, Rachel Ray, and Kim Cattrall.

Mad Men actor Vincent Kartheiser became one of the newest members of the club; he announced this fall that he intends to go childfree — and for environmental reasons, no less.

On the literary front, Jonathan Franzen‘s bestselling novel Freedom has an overpopulation leitmotif and an environmental-activist character, Lalitha, who declares her intention never to have kids.

Polly Vernon wrote “Why I don’t want a baby” for Marie Claire, Brittany Shoot wrote “Why I got my tubes tied at 27” for Salon, and yours truly wrote “Say it loud: I’m childfree and I’m proud” right here in Grist.

Other childfree evangelists blogged and tweeted, worked on documentaries and audio programs, and occasionally even made it onto TV.

FML

But ironically, the most compelling arguments for the childfree lifestyle this year came from parents.

Take the much-buzzed-about cover story in New York magazine, “All joy and no fun: Why parents hate parenting” — or, as the cover put it, “I love my children. I hate my life.” Jennifer Senior writes with jarring frankness about the downsides of parenting:

Most people assume that having children will make them happier. Yet a wide variety of academic research shows that parents are not happier than their childless peers, and in many cases are less so. … Perhaps the most oft-cited datum comes from a 2004 study by Daniel Kahneman, a Nobel Prize-winning behavioral economist, who surveyed 909 working Texas women and found that child care ranked sixteenth in pleasurability out of nineteen activities. (Among the endeavors they preferred: preparing food, watching TV, exercising, talking on the phone, napping, shopping, housework.) This result also shows up regularly in relationship research, with children invariably reducing marital satisfaction. The economist Andrew Oswald, who’s compared tens of thousands of Britons with children to those without, is at least inclined to view his data in a more positive light: “The broad message is not that children make you less happy; it’s just that children don’t make you more happy.” That is, he tells me, unless you have more than one. “Then the studies show a more negative impact.”

Senior’s grim portrait of parenthood is accompanied by a tantalizing description of the idealized childfree life:

Lori Leibovich, the executive editor of Babble and the anthology Maybe Baby, a collection of 28 essays by writers debating whether to have children, says she was particularly struck by the female contributors who’d made the deliberate choice to remain childless. It enabled them to travel or live abroad for their work; to take physical risks; to, in the case of a novelist, inhabit her fictional characters without being pulled away by the demands of a real one. “There was a richness and texture to their work lives that was so, so enviable,” she says.

Even the author of the forthcoming book Selfish Reasons to Have More Kids, economics professor Bryan Caplan, started from the premise that parenthood is a bum deal in a Wall Street Journal opinion piece that ran in the spring. It’s “true that modern parents are less happy than their childless counterparts,” he admits. “[C]hild No. 1 does almost all the damage,” he writes, citing the National Opinion Research Center’s General Social Survey. But here’s his positive angle: “Each child after the first reduces your probability of being very happy by a mere .6 percentage points.” Color me unconvinced.

Lots of people love parenting, of course, or are perfectly willing to make tradeoffs in order to enrich their lives with children. And lots of celebs are still hamming it up for the paparazzi with their picture-perfect progeny, fanning the “baby bump” craze.

But in 2010, it became clear that the pro-parenting contingent is no longer the only game in town.

It’s about time, because in 2011, we’ll get a big reminder that there are already plenty of us around — 7 billion reminders, actually.