Sex has always been a public concern for a number of reasons, not least of which is the fact that reproduction tends to require it. Who is having sex with whom? Who is procreating and how many times? No society has ever been indifferent to these questions. Their answers reveal who will hold power, the size and quality of a society’s fighting force, and the agricultural and architectural needs of generations to follow.
Twenty-four hundred years ago, Plato’s Republic laid out explicit and detailed instructions for how a hypothetical city’s rulers should manipulate its populace into participating in a eugenic breeding program to maintain balance and harmony, which Socrates calls “justice,” between all classes within the city. The preoccupation with sex and reproduction as a civic problem is not new.
What is new is that, for the first time in human history, the global population is projected to contract not due to war, disease, or hunger, but because individuals everywhere are choosing to have fewer babies. Seemingly overnight, scientists and politicians swung from fears about scarcity caused by overpopulation to panic about the economic and cultural impact of declining birth rates and aging citizenry. It’s not just reproduction that is falling, but intimacy too. Even before the pandemic, young people in America were not getting it on at the same rate as previous generations, and the trend has only accelerated in the last five years.
From Thomas Malthus to Idiocracy, the threat of unsustainable overpopulation has been the dominant paradigm for centuries. Highly urban civilizations have dealt with the problem of overcrowding since the days of Uruk, but generalized concerns about overpopulation did not emerge until the modern, globalized era following the Industrial Revolution. Malthus, an English economist, observed in 1798 that food production grows arithmetically while population grows exponentially. Eventually, the demands of the latter will outstrip the capacity of the former. In the 20th century, as the cost of pollution and climate change became clear, concern gradually shifted from the threat of famine to the growth-driven spike in carbon emissions catalyzing extreme weather events, which will eventually render large swaths of the globe functionally uninhabitable.
Then the new millennium brought new fears. In recent years, Western media has developed an obsession with a strange trend in the opposite direction in Japan and South Korea. Around 10 years ago, I recall a glut of voyeuristic media coverage on this issue: long Atlantic articles about strange, sexless Japanese youth and Vice clips about simulated intimacy or the animatronic stuffed seals being deployed to address the country’s elder care crisis. Even China, with its famous and disastrous one-child policy, is now desperate to reverse course and grow its population once more. We red-blooded Americans liked to gawk at those alien Orientals who couldn’t even figure out how to reach their population replacement rate.
But American birthrates had been falling, too. They’ve been on a steady decline since a peak in 2007. Everywhere you look in the developed world — and in many developing countries too — birth rates are slipping near or below the replacement rate of 2.1 children per woman. The UN’s “World Population Prospects 2024” report projects that the global population is likely to peak at over 10 billion in 2080, then begin to fall. The peak will come sooner, in the 2040s, for high-income countries, which will also need to support a higher proportion of elderly residents.
This was beginning to filter down to laypeople like me pre-pandemic, but it only became a mainstream concern within the last few years. Prior to that, demographic anxiety and such distasteful ideas as “The Great Replacement”1 were a fringe, hard-right preoccupation. Now, alt-lite trolls and blonde, barefoot tradwife influencers are spreading their pronatalist propaganda everywhere.
Fiction is finally starting to catch up with this new, soon-to-be-shrinking world. Speculative fiction has largely foreseen ever-accelerating growth, in many cases with space colonization serving as an escape from an over-crowded Earth. Where an author creates a post-apocalyptic, depopulated Earth, the cause is usually cataclysmic: a nuclear war, a global pandemic, or the collapse of agriculture.
There is a subgenre of speculative fiction I call “birth rate fiction.” This is fiction that takes as its premise the consequences of changes in a society’s birth rate. A sub-subgenre of birth rate fiction is “population bomb fiction,” which takes overpopulation as its premise and its name from the 1968 nonfiction book by biologists Paul and Anne Ehrlich, who warned of impending global famine and mass starvation in the face of a population explosion. Although the predicted calamities never materialized, the book was a bestseller and its anxieties influenced generations of policymakers.
I recently read Harry Harrison’s Make Room! Make Room! (1966), the book on which the Charlton Heston movie Soylent Green (1973) is based. My edition features an introduction by Paul Erhlich, solemnly noting that the nightmarish dystopia depicted of a vastly overpopulated New York City is less a work of science fiction than a sneak preview. In Harrison’s New York of 1999, birth control is stigmatized and hundreds of millions of Americans strain the nation’s food production capabilities. A permanent, bloated, immiserated underclass struggles to survive on ever-dwindling rations. Rebels upstate sabotage the water pipelines into the city. Every square foot of habitable space is occupied. Crime goes largely unpunished and the breakdown of social order is a regular occurrence.
Other works of population bomb fiction include the cannibalistic dystopia of Anthony Burgess’ The Wanting Seed (1962), which bills itself as “a Malthusian comedy,” Stand on Zanzibar (1968) by John Brunner, and J. G. Ballard’s “Billennium” (1961), the short story of a claustrophobic real estate farce in a disastrously crowded metropolis. Although each of these works differs in the extent of its fantastical elements, the organizing principle among them is that each seems to ask not “What if,” as most speculative works do, but “When?” Their shared assumption is that the track has already been laid that will take us to these terrible, logical conclusions.
The other side of the population bomb fiction coin is “birth rate collapse fiction.” Margaret Atwood’s The Handmaid’s Tale (1985) and P. D. James’s Children of Men (1992) are the most prominent two that come to mind, each exploring the catastrophic sociopolitical implications of a sudden decline in birth rate. These stories are less common in the canon of speculative fiction, but as we come to terms with our global demographic trend about-face, the literature is growing.
The latest entrant in the English-language corpus of birth rate collapse fiction is the new translation of Sayaka Murata’s novel Vanishing World (2015), translated by Ginny Tapley Takemori and published by Grove Atlantic in April 2025. Although declining birth rate is not an explicit feature of the book, the decline of sex and love that it illustrates is a clear extrapolation of the real-world demographic crisis gripping the island nation.
Set in a contemporary, parallel-universe Japan in which postwar advances in artificial insemination shifted cultural norms away from copulation and eventually even romantic love, the book follows our narrator, Amane, a young woman who is one of the last people to have been conceived through sexual intercourse. She grapples with the urge to conform to her sexless society while navigating her own increasingly stigmatized desire. In this world, romantic love for fictional characters is encouraged, and even those who fall in love with real people seldom engage in sexual activity with them.
Amane is unusual in that she is attracted both to fictional characters and to real people — and even more rare, she has sexual desire for both categories. In this alternate Tokyo, the custom of marriage remains for the purposes of companionship and financial security, but sexual contact between spouses is considered perverse and branded as incest. In fact, Amane divorces her first husband after he kisses her and attempts to have sex with her:
I was horrified. I’d never imagined that a member of my own family would have an erection because of me. I tried to scream, but he covered my mouth with his. I felt my tongue being licked all over, and nausea welled up within me. I vomited into his mouth, and as he recoiled I pushed him away and ran into the toilet, where I threw up again and again.
Amane reports her husband’s attempted intimacy to the police, who are horrified on her behalf and shelter her while she makes alternate living arrangements. Sex between spouses is considered a perversion, while extramarital sex is tolerated but thought of as unclean: “Love and sexual desire were like waste material, something to be disposed of outside the home.” Amane’s second husband, with whom she enjoys a more harmonious union, shares this normative belief and gratefully confides in her: “The outside world is soiled by my feelings of love and my sexual appetite. The only place I feel clean is at home.”
The book is obsessed with cleanliness and disgust. Despite the narrator’s obsession with sex, it is not an erotic book. The multiple sex scenes are written with clinical, antiseptic distance. The overall effect is deeply disturbing, occasionally repulsive, and often hilarious, all at the same time — as in the above-quoted passage. When Amane takes on a new real-world lover, Mizuto, he has never had sex before and needs to be taught.2 She explains the signs of arousal, and they look at sexual images on their cellphones together:
For a while we sat in silence, staring at our phones, and when I felt I was ready I said, “I think I’m okay now.”
“Yeah, me too, I think. What do we do now?”
“You have to put that into something called the vaginal opening. I don’t think you can find it by yourself, so I’ll show you.” I opened my legs and pointed to my vagina.
“I can’t really see any opening . . . Is that okay?”
“It’s made from quite an elastic material, so it’s okay.”
“Weird. Did people in the old days really do this?”
“Everyone did, apparently. I mean, this is how humans are designed to copulate.”
“Very strange.”
Mizuto looked totally mystified as he pushed his penis against my groin.
“Now you have to move your hips to stimulate our sexual organs. Then some liquid will come out of your sexual organ, Mizuto, and when that happens, it’s over.”
“Sounds difficult! I’ll do my best.”
By trial and error we stimulated our sexual organs, and eventually some liquid came out of Mizuto.
The inside of my vagina was dry, and I felt a sharp pain that I’d never felt before. The sensation of water flowing into my body was much more mysterious than usual. It felt like Mizuto was making it rain inside my body.
Vanishing World shows us a realm in which the fundamental human drives to seek love and sex have become obsolete. Ultimately, it’s a story about what it means to be “normal” in a changing culture. Amane, in spite of her sexual deviancy, is not an embittered, alienated outsider on the margins of society. She actively strives to conform, finding that her inner life is shockingly malleable — up to a point. When we finally reach that point at the very end of the book, what results are 10 of the most disturbing pages I have ever read. It’s a brilliant, shocking conclusion to an eerie novel.
This isn’t a reading experience that will appeal to everyone, but it’s clear that Murata is a major talent. I want to be unsettled by my literature. I crave new and intense inner experiences, and Murata delivers them in spades with Vanishing World. She is a prophet for the new social paradigms emerging, first in the East and now in the West — a writer to show us how perverse our normalcy can be.
Lillian Wang Selonick is a writer and science communication professional in the Washington, D.C., region. Her work has been published in Futurist Letters, The Republic of Letters, Joyland Magazine, Variant Literature, Ricepaper Magazine, and others. She writes about classic literature and science fiction on Substack at The Lillian Review of Books. Find her on Substack or at lillianwangselonick.com.
Roughly, the Great Replacement theory is the idea that Jews, mostly, are engaged in a conspiracy to import massive numbers of nonwhite immigrants while driving down native-born fertility to replace white Americans and Europeans.
This decoupling of sex from love and reproduction brings to mind the song “Drive-In Saturday” by David Bowie, which envisions a glam doo-wop post-apocalyptic dystopia where sex has been forgotten and needs to be relearned: “Perhaps the strange ones in the dome / Can lend us a book, we can read up alone / And try to get it on like once before / When people stared in Jagger’s eyes and scored / Like the video films we saw.”
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Enjoyed reading this! Regarding the Western obsession with East Asian birth rates, I remember reading a Slate piece from the early 2010s by Josh Levin that pointed the double standard in how the West liked to view falling European birth rates as the fault of capitalism (e.g. youth unemployment, high housing costs) while falling East Asian birth rates as sexual defectiveness, especially in the men. It was effective copium for many Americans: 'Whew, at least we're going to avoid that fate because we're not commies like the Euros and we're not dickless nerds like the Asians.'
So it's been pretty funny watching that panic now take hold in America, with people blaming stuff like Gen Z Boss and a Mini for American youth sexlessness.
Actually...Plato's Laws include projected laws to force men to marry. Augustus, in Rome, instituted bonus rights to encourage having children (the 'ius trium liberorum' was accorded to women who had three or more children). Of course, Plato himself had no children as far as we know, and Augustus's one biological child was put out of the way fairly early on. Wealthy, educated, and successful societies/classes have always had fewer children than some utopians and lawmakers have wished.