When she turned 30, Emily Witt sold a book proposal that she was not entirely committed to: a straightforward cultural history of sex in the internet age. At the time, Witt, who is a contributor to n+1, The Paris Review, and The New Yorker, questioned not the viability of her subject but herself as its interrogator. "I thought, Why would I do this?" she recalled at a Brooklyn bar near her home on a recent afternoon. "I'm boring, I'm insecure, I had a boyfriend. But I felt that I wanted to tell a story about right now. And sex is a major subject that seemed so urgent to everyone around me."

Then the publishing gods seemed to smile down upon her, in their cruel beneficence. Witt and her boyfriend broke up, to her personal chagrin, and suddenly she had both a compelling story and a voice for her subject — her own, hardened but newly curious. "The year I turned 30 a relationship ended. I was very sad but the sadness bored everyone, including me," Witt writes near the beginning of Future Sex, which is part memoir, part reportage, and part essay collection. (Chapters include: "Internet Dating," "Live Webcams," "Polyamory," "Burning Man.") While it is a first-person exploration of modern relationships by a single, straight woman, Witt's voice has a clear-eyed restraint and a tough, ironic sense of humor, especially when it comes to herself. There is very little about the book that is treacly or overheated. (It's "a gutsy first book," according to The New Yorker's Alexandra Schwartz).

But for all its steel and smarts, her story is nevertheless moving on a personal level. Though there is sometimes the sense that Witt is feeling gingerly around her still-fresh bruise, she is unafraid to touch the marrow of the matter: "When I first began to explore the possibilities of free love, I still half-expected that destiny would meet me halfway, that in the middle of all the uncertainty I would come across an exit ramp that would lead me back to all the comfortable expectations and recognizable names ... I was so disingenuous," she writes.

"Part of the reason that I wrote the book in the first place was that all these articles about single women felt like a dead end," Witt, now 35, explained. "They described the confusion that I was feeling now that my expectations for my adult life might not turn out the way I wanted because the world had changed. But they didn't describe a way out of it. They only lamented the decline of the date followed by the engagement followed by marriage."

Witt would seek her own answers then. Into the world of dating in the 21st century she plunged, newly single in 2011. She had casual sex with friends. She had a (false) chlamydia scare that threw her into an existential fright. She investigated the history of internet dating, tracing its origins from Match to OkCupid to Manhunt to Grindr to Blendr to, eventually, Tinder (which was not around when she started working on the book). Of course, she used these services, too, as unfruitfully as many others. She arrived at conclusions that, like the naked bodies brought to us by the apps, can surprise in their stark obviousness once the imagination and fantasy has been undressed: "... the technology itself promised nothing," she writes in the chapter on internet dating. "It brought us people, but it did not tell us what to do with them."

Most of all, during this time of belated sexual discovery Witt left New York for San Francisco, which was just beginning to become the moneyed tech playpen it is today. "I was never going to let myself go in the way that I could in a city full of strangers," Witt explained. "Plus it's an empirical fact that San Francisco is a city where people talk about their sexuality more."

Photo by Landon Speers.

At a San Francisco company called OneTaste, she tried orgasmic meditation, during which a man strokes a woman's clitoris for a prescribed period of 15 minutes while poetically describing her vulva back to her. If this appalls you, consider the orientation before Witt ever made it to that stage, which involved an assigned male partner who recounted, seemingly without guile, her own features to her. "As a man described to me the traces of my makeup, a blemish on my chin, and other flaws in my appearance that I had convinced myself were too small to be noticeable,” Witt writes, “I felt a unique experience of horror.”

She visited the set of Kink.com, a BDSM site located in the Mission that specialized in the Public Disgrace genre of internet porn, which is exactly what it sounds like. There she encountered a male porn star, Ramon Nomar, with a penis “like the trunk of a palm tree," and a female performer named Penny, who when asked, after a long scene of Disgrace-ment, which of the several painful-looking acts of sex were actually pleasurable, replied happily: "Like the whole thing!"

Witt signed up for Chaturbate — "It was amazing, the diversity of what men wanted performed for them and how little they offered to others," she observes — and got into the Bay Area's polyamorous scene, involving herself in the lives of three supremely well-adjusted Google employees in a lust triangle that was on the verge of becoming something more. "I've been in love with two people at the same time," Witt said. "And there was no way I could have been like, 'Okay, you be my primary relationship, and you be my secondary. And we're all going to tell each other about our feelings, and just be cool with it.'" She looked at me, incredulous. "That's not the world I live in."

Witt's intellect hovers so presently in the book, that the times when some experience manages to undo it makes those scenes all the more powerful. When she went to Burning Man to meet up with a guy she encountered at a wedding, they hooked up in his trailer. Witt writes: "I want to have sex with this person forever." No further analysis necessary.

"I'm way less embarrassed and shy than I was sexually," she admitted. "I used to be scared of a lot of stuff that doesn't scare me anymore. I'm more forgiving of people who are trying to live an original life of some kind, even if I can see it failing. I thought of myself as a liberal person, and then I realized all the ways I was constantly casting judgment on people, on myself, on who I was or wasn't. There's always this fear that you're going to open up too much and become this woo-woo, West coast, human-potential movement type person who believes in faeries and unicorns. I don't know where that limit is, still." She laughed. "Maybe I've passed it; maybe I've become that person."

Photo by Landon Speers.

Although Witt didn't set out with the intention of tracing this particular plot — "It wasn't contrived that I have this catharsis that changed the book," she said — her own personal journey informs the tone of the Future Sex, which arrives in the end where it started, only with more clarity and hopefulness. In the future, the act of sex won't change; only the ways in which we think about it will.

I asked her if she can now, after all her investigation and pondering, better determine the differences between dating, love and sex. "I just think of it all as sex now," she replied. "Just different kinds of sex." She went on: "We organize our society around the way we define our sexual relationships. And when you pretend it's about other things — that it's about liking the same books, or that it's about getting married — and that the sex is secondary, that's when you end up risking a lot of unhappiness."

And then, at the risk of endangering all this sober critical thinking, Witt revealed she was, in fact, now in a relationship — a serious one. "The whole book was written with the idea, What happens if you never fall in love, and how will you live your life then?" She laughed. "And now I've gone and fallen in love."