Gendercide

"Wonder Woman: Half the city is dying. Batman: Yeah. The male half."

- Justice League

A Depopulation Bomb variant that removes approximately half of the population of the world in one stroke, namely one complete gender, with one exception. The exception will be the protagonist, love interest, or MacGuffin of the story.

If it is the males who die off (as is most frequently the case), the story will be about how the surviving women rebuild society, or how Fish Out of Water males cope with a society that has already been rebuilt. If it is the latter, the Last Man on Earth, our hero, may initially think that his life is going to be all orgies and pampering from now on. This is classic Genre Blindness, as stories of this type almost never fit this pattern. The last man will quickly become a target, sought by every woman of power and means in the world, as his sperm may be the key to the survival of the human race.

This type of story seems to exist for several reasons. Primarily they exist to explore gender politics and behavior, but they also have the secondary benefit of providing an excuse to write literature in which most of the principal characters are female (a major change from a lot of fiction). In addition, classic gender roles, the glass ceiling and to some extent in some cases biology being what they are, the death of all men would effectively decapitate most of the world's organizational structure, meaning descent into chaos is likely, especially in stories set before 1970. This collapse (and probable renewal) of society provides an excellent source of conflict for writers to build their plot around. And finally there's Rule 34: being one of the few males alive (fertile or not) gives our hero the chance to seduce every woman he sees, which is a popular trope on the horny side of the Web.

Some hard-line feminist authors might create this kind of story as a utopian vision, in line with their view that men are the root cause of all the ills of society. Some anti-feminist authors might create exactly the same kind of story to produce a dystopia, to show that feminists are the cause of all the ills of society (see for example Edmund Cooper's Gender Genocide). Still others take the stance that humans are the cause of most human problems, and that if men aren't calling the shots, women will still make the same short-sighted and foolish decisions (at best, all new short-sighted and foolish decisions). The total collapse of society in these cases is not because of some inherent flaw in female leadership, but because three-and-a-half billion people just died all at once, with all the problems that causes. Either way, the dirty secret of these stories is that they're usually actually there to impart some political message, sometimes subtle and unobjectionable, sometimes not.

When all the women die off, the story is usually less about politics or gender issues and more about The End of the World as We Know It. These stories almost always take place After the End, in either a cruel Dystopia or a chaotic Scavenger World. Either way, the clear implication is usually that without the "calming presence" of women, the men will immediately nuke themselves to hell out of sexual frustration and other "manly" demands. Such a setting is of course highly prone to feature brutal male-on-male rape to add to the Nightmare Fuel, or for other reasons. Note this can happen with the women-left scenario, but much less often and with the rape part virtually nonexistent. The situation is slightly (but only slightly) less sexist if the men are "fighting over" the remaining women (in which case, there's at least a reason for conflict).

The name is a pun on genocide, and was first used by Mary Anne Warren in her 1985 book, Gendercide: The Implications of Sex Selection.

See also Gender Rarity Value and Childless Dystopia, both of which this trope is a prime setup for. If all of the members of a gender dies off, you may result in a One-Gender Race. Compare Sterility Plague, which can enable similar kinds of plots.

Anime and Manga
"The Woman-Nation, First Movement: Ancient Mankind (Track 3) The Woman-Nation, Second Movement: Collapse and Eradication of Male-Dominated Civilisation (Track 4) The Woman-Nation, Third Movement: Engineering and Preservation of a New Species (Track 5) The Woman-Nation, Fourth Movement: Founding of the Woman-Nation (Track 6)"
 * In the anime Girl's Bravo, the alternate dimension of Seiren has a 10/1 female/male ratio. The main character, milquetoast gynophobe Yukinari, gets propositioned by a couple of grade school girls and chased by virtually the entire female population of a city that has very few, or possibly no, men in it before he escapes back to Earth.
 * The So Bad It's Good anime OVA ICE takes place In a World where all men died after the space station Mir unexpectedly crashed into the ocean while still carrying experimental toxic substances. Girls Love ensues, obviously.
 * In the hentai manga St. Margareta Academy, "chromosome abnormalities" have caused a 25-to-1 female/male ratio; as a result, statistics show that 90% of all women will be deemed "useless to society", and are federally forced to enroll in a special school training sex slaves through S&M classes for nine years, for the purposes of "social services". Extremely disturbing (to put it mildly) BDSM ensues.
 * Vandread seems to be something like this early on. In this show's take, the all-male planet develops into a paranoid fascist dictatorship, while the all-female planet is a constitutional democracy. However it shows the men of their planet having few resources surviving in a harsh unforgiving world, where as the women inhabit a planet rich in resources but are morally and socially deficiant, constantly trying to one up each other and waste the resorces they have aplenty frivelously.
 * Yokohama Kaidashi Kikou does this with the relationship between male and female androids.
 * The manga Ooku: the Inner Chambers begins with a disease that kills off a large proportion of the male population of Japan during the Edo period. Subsequently, males continue to die of the disease while women take over almost all productive roles in society, including the shogunate. Only the female shogun is wealthy enough to keep a harem (the titular ooku) full of non-productive, pampered men in her care and, like its real-world female historical equivalent, the male harem lives a strictly cloistered life.
 * An alien example in the backstory of the Arume of Blue Drop. Once again it's the men who died out. The women solved things by giving themselves some male genes so that women could reproduce using machines to facilitate the process; it was only a stopgap measure and wouldn't keep them going forever. They made a smashing attempt to go get the last male Arume genes from human males on Earth (there were apparently some Ancient Astronauts a while back who got... busy). They chickened out in the end, though, having become too used to the new status quo, and took our women instead.
 * The Yuri Hime serial, Love DNA XX involves humanity contracting an epidemic that causes no males to be born. After the last man dies off, the governments start enforcing a rigid new gender system on the leftover females splitting them into "Adams" and "Eves". Though to be precise, it's not so much a new gender system as the same old one but more arbitrarily assigned.
 * One of the fictional comics of Bakuman｡ goes downhill when it has a Gendercide plotline.
 * It's only seen in the titles of the soundtrack songs, but this was apparently done to men after a sex-based civil war/armed rebellion in the backstory of Simoun:

- Simoun OST 1


 * A modified version appears in Macross: Do You Remember Love?: the Zentradi and Meltrandi (men and women of the same race, respectively) are actively trying to kill each other to such an extent that seeing the two genders peacefully coexisting on the Macross weirds the hell out of them.
 * Aquarion Evol:

Comic Books

 * The entire premise of Y: The Last Man. A Comic Within The Comic, made by a female survivor, tells the gender-reversed version.
 * The DC Elseworld story Created Equal is one of these, with Superman as the last man.
 * The adult comic Naked Earth.
 * In Enki Bilal's Nikopol Trilogy, Paris is introduced as a facist city-state where the Depraved Homosexual elite uses eugenics to minimize the percentage of females in their population, and keeps them out of sight in underground breeding farms. The eponymous protagonist, Alcide Nikopol, puts an end to the practice while turning the city-state to communism with the aid of the rebellious Egyptian god Horus. It's a surreal comic.
 * XXXenophile had one story where a naked male time traveler shows up in a woman's closet. He's from a future where all women have been wiped out and men reproduce by cloning. One side effect of the gendercide is that they got rid of all wars, starvation and diseases, and generally built an utopia, but now they've began to wonder if those "women" weren't good for something after all and maybe they should be brought back, so he's sent through time to conduct research. Thus, much acrobatic researchis had, after which he concludes that women are a very good thing to have after all.

Film
"Ian Malcolm: God creates dinosaurs; God destroys dinosaurs; God creates man; man destroys God; man creates dinosaurs. Ellie Satler: Dinosaurs eat man ... woman inherits the Earth. [Malcolm and Grant give Ellie a vaguely worried look]"
 * Hell Comes to Frogtown, in which "Rowdy" Roddy Piper plays Sam Hell, one of the last fertile men on Earth (and is thus in high demand). Along with Sandahl Bergman doing a sexy dance and a man-sized frog.
 * The Last Man on Planet Earth, A TV movie where a biological weapon, intended to kill the majority of soldiers on the opposing side, escaped its intended bounds. Some years later, in vitro fertilization seems to have taken the place of natural birth. Some men have survived, but they're fanatics, convinced that they should still be in charge. A female scientist manages to clone a man and quick-grow him to adulthood in a matter of weeks. Then she has sex with him and gets pregnant... There are women in this setting who like to make it out that the world is a much better place without the men; but given the eagerness some of the women show in destroying their enemies, it's implied that the women aren't much better.
 * Used on a smaller scale (with, of course, the exceptions of the love interest and the plucky teenage girl) during the latter half of 28 Days Later. With a dubious twist- the only reason men outnumber women in post-quarantine England is because the majority of the survivors were soldiers holed up in a manor house in the countryside as a makeshift headquarters. The Virus has identical effects on women and men, the men just have bigger guns. The end result of the soldiers' nine man society at first looks hardly dystopian -- apart from the blood spewing pseudo-zombies and the general feeling of depression -- up until the last women in England showed up, at which point they practically all turned into crazy rapists, presumably because they were convinced they were the last humans alive on Earth and the whole set-up was designed specifically to attract women so that they could alleviate this sense of despairing hopelessness by 'rebuilding the species.'
 * Polish Cult Classic Sex Mission is about two men waking up from cryogenic sleep to discover that they're apparently the only males in the world now. Hilarity Ensues.
 * David Cronenberg's Crimes of the Future is set in the world where women has killed by a disease, Rouge's Malady.
 * The first Jurassic Park movie has a reference to this. As they're driving through the park, Malcolm starts in on one of his little monologues, before Ellie commandeers it. Also apparently a Lampshade Hanging on the fact that women and girls tend not to die in Spielberg's work.


 * Gayniggers from Outer Space has the aforementioned extraterrestrials freeing the male population of Earth from evil oppressive "female creatures" and leaving a gay ambassador to instruct the men of earth in their new homosexual lifestyle.
 * Implied after the end of Dr. Strangelove. With the nuclear holocaust imminent, Government leaders plan to hole up in mineshaft shelters with 10 women for every man. Gen. Buck Turgidson is very excited at this prospect, provided the US doesn't suffer a "mineshaft gap". When you think about it they seem to be suggesting a pretty squicky prospect where every man will have ten sex slaves (beauty was mentioned as the main criteria), and women have little function other than breeding. It would be interesting to see what would happen after the women realized their odds would be ten to one.
 * In Casino Royale 1967, Evil Overlord wannabe Woody Allen has developed a strain of bacteria that, when released, would turn every woman beautiful and destroy every man over four foot-six (or taller than him).
 * On Venus, all the surviving men have been exiled to an orbiting moon in the sexist camp classic Queen of Outer Space, staring Zsa Zsa Gabor. All it takes to put these ladies back in their place is a trio of red-blooded American astronauts with enough Vaseline in their hair to a drown a bat.

Literature

 * In Joanna Russ' short story "When It Changed", a planet is colonized by Earth, but all the men die. In a twist, the women don't do a super better job at running things, though they are able to live fairly well on the planet. Unfortunately, men from Earth come and imply they will force the women to mate with them if the women refuse to do so willingly. As the women are all now lesbians (and have invented a way to have children), this does not bode well for them. Arguably Anvilicious, but sf in the early 1970s still had some gender issues.
 * Margaret Atwood's The Handmaid's Tale plays with a variant of this, in which 95% of all women were rendered sterile by a plague. This leads--in America at least--to a rigid theocracy which virtually enslaves the few remaining fertile women. The men are also frequently sterile but the theocracy insists that failure to produce children is the fault of women. This leads to handmaids trying to secretly conceive children by fertile men to prevent themselves being declared barren and sent to the work camps.
 * The feminist novel Herland, by Charlotte Perkins Gilman: The men of a tribe all kill themselves in a war, leaving the women to randomly develop the ability to reproduce parthenogenically and found a Utopia.
 * Frank Herbert's novel, The White Plague (here, it's the women who die).
 * Joanna Russ's The Female Man features a man-less world as the home of one of the principal characters. It is unabashedly utopian, and though it's stated it's the result of a plague that wiped out men in the distant past, there's one or two hints it might instead be the result of one of the other alternate worlds, where men and women are at war with each other. Russ was anything but subtle about how she felt women were held down by men. One of the longest, most detailed passages concerns a woman warrior from the latter world literally tearing a man apart with her bare hands, which may have been Russ working out some frustrations.
 * The Rainbow Cadenza is a libertarian sci-fi novel by J. Neil Schulman where men outnumber women seven to one, and all women are drafted into prostitution for three years. This happened due to a number of long wars in which more men were created (via chemicals which affected the gender of the sperm) than women.
 * Alice Bradley Sheldon/James Tiptree Jr.:
 * The novella "Houston, Houston, Do You Read?" is about a group of male astronauts on a circumsolar mission who run into trouble and are trying to contact Houston to return to Earth. They get picked up by a ship crewed only by women, and spend a good deal of time asking where all the people (meaning the men) are. Turns out, their ship had slipped through time several hundred years and in fact a plague had wiped out all men and most of the women on Earth, leaving only 11,000 survivors. The world the guys returned to had no crime or war but also no advancement.
 * The short story 'The Screwfly Solution' (also made into a Masters of Horror episode) has a rather disturbing version of this trope. Aliens distribute a virus that causes human mating behavior to change, turning men's sexual impulses into violent ones, essentially turning them all into psychopathic serial killers bent on destroying all women (and occasionally little boys). Once they have accomplished this, the aliens simply have to wait for all the surviving men to die before they move in and take over the earth. The story's title is based on a real-life method for eradicating Screwfly, which uses a hormone that subverts the fly's mating instinct so that the males mount the females in the wrong way, so no conception can occur. So, Truth in Television?
 * John Wyndham's novella "Consider Her Ways" features a world in which men have been killed off by a virus, etc, etc. The protagonist is a woman from our world who "travels" there while under the influence of an hallucinogenic drug. It was All Just a Dream -- Or Was It a Dream??
 * In one of Cordwainer Smith's stories about the Instrumentality of Mankind, "The Crime and the Glory of Commander Suzdal", the settlers an isolated planet nearly lose all the women to a virus or mutation which "turned femininity carcinogenic". A few surviving women actually turn themselves into men through massive testosterone injections and manage reproduction through embryonic implantation. Over the centuries their memories of womanhood and eventually the Earth itself are twisted into monstrous hatred. Then Commander Suzdal shows up in his scout ship...
 * Chaos Walking: In The Knife Of Never Letting Go, the protagonist Todd Hewitt grew up on an alien planet, in a town where there are no women. For his whole life, he believed that the reason was a Depopulation Bomb, which killed off all the women and had the side effect of allowing everyone to hear the men's thoughts. The truth is much more sinister.
 * In The Queen of The Damned the titular Vampire attempts this with males. By her own power. Or worse. A bunch of boys and girls who are just entering puberty, and no adult supervision? And yes, that was the official reason for the lack of girls.
 * Robert Merle's novel The Virility Factor, where a virus kills most men capable of reproduction, and a misandrist regime comes to power in the United States. When the cure for the disease is discovered, it falls, and the society starts treating the remaining men as sex objects.
 * In David Brin's Glory Season, a space ship of feminist colonists goes to a far, far away planet in order to create a perfect society. The women are in charge, and whenever one of them finds their 'niche' in society, they clone themselves over and over. There are men left alive, because the scientists knew that if their society was completely stagnant, eventually something would kill them. So, we have the clone children, or "winter children" who are the majority of the population, and then "summer children" who are born when men who have proven themselves useful get to vent their genetically suppressed lusts during the summer. The summer children are also called "variants", and the protaganists goal through the book is to find her 'niche' and be allowed to have a clone child.
 * In Honor Harrington, the planet Grayson has a fairly mild, albeit long-lived, form. Some desperate genetic engineering to save the colonists from a Death World in the backstory results in roughly 2/3 of males being miscarried. This state of affairs continues for almost a millennium, until they get access to advanced enough technology to figure out what happened and reverse it. It's a lot less destructive than most other examples, however - they pretty quickly adopt polygamy and move on with life.
 * In John Varley's Gaea Trilogy, the moon is bought out by a group of women called The Coven, who detest men. They're all lesbians, but they reproduce by ordering sperm shipments from earth.
 * Sheri S. Tepper, being an overtly feminist author, might be reasonably expected to use this, but in fact she averts it more than once in favour of a fate worse than extinction. In Gibbon's Decline And Fall, a misogynist cabal plans to use . A variation of this idea occurs in The Companions, which features an alien species in which the females are supposedly naturally incapable of rational thought, and have been for countless millenia.

Live Action TV

 * An episode of Sliders. Gendercide was the result of a virus, all male survivors were kept in isolation at a secure sperm-bank facility. Australia had become a world power due to having gotten less of the virus and therefore having more men.
 * The Masters of Horror episode "The Screwfly Solution" involves an epidemic of male-on-female violence
 * Occurred in an episode of Blake's 7, where a group of women were trying to exterminate all men. Avon summed it up nicely: "It's a problem, isn't it? You can have war between races, war between cultures, war between planets. But once you have war between the sexes, you eventually run out of people."
 * Happened in "Lithia", an episode of the Outer Limits revival, where the few surviving men were Human Popsicles. The thawed soldier protagonist proceeded to raise merry hell in the all-female society that sprang up, but it was prevented from being an Anvilicious misandrist Take That by the fact that, as ham-fisted and ill-advised as the man's attempts to change it were, the new society was utopian only in appearance (i.e. what with the leadership's rampant favoritism in resource allotment and Big Brother-esque control on the information flow). It ended with him being "put down" (euthanized or refreezed, can't remember) and the leadership declaring that trying to make men return was ill-advised, and that all efforts to do so would be ceased . Just to twist the knife further,.

Music

 * Believe it or not, there is a music example. "Cemetery Girls" by Schoolyard Heroes is about a Gendercide in which all males die.
 * Believe it or not, there's another. In "Extermination Day", by the NWOBHM band Angel Witch, a superior race of female aliens invades Earth and eliminates the male gender as punishment for violations of human rights.
 * There was a hit rockabilly song in the 1950s entitled "Thirteen Women and Only One Man in Town"; it experienced a resurgence in popularity in the mid-1990s. What many people did not know, either then or now, was that the song alluded to the only fourteen people left on Earth following a nuclear holocaust. Lucky guy....

Mythology

 * The original Greek depiction of the very human Amazon civilization variably implied they replenished their numbers the way most warrior cultures did, from invading villages. And depending on how charitable the writer was, any male children were either returned to be reared in those villages, or killed.

Video Games
"Great...(slowly) That makes me the last woman on Earth."
 * The N64 game Battle Tanx starts when a virus kills 99.9% of the women in Earth; the remaining ladies are promoted to living goddesses, the countries start fighting for other quarantine zones, and they finally engage in nuclear war. The protagonist Griffin Spade, who lives in New York, has his fiancée taken away by the government, so he seizes an M1 Abrams tank and sets out to travel across the USA to find her. In the sequel, it's revealed.
 * Played with in Fallout; vault 69 was populated by 999 women and 1 man, likewise Vault 68 was the same, except with 999 men and 1 woman. The vaults were purposefully built social experiments of the cruelest nature, and were specifically designed to experiment on how much stress a society could take before the people broke down into civil war.
 * Averted by Word of God in Touhou. Why would having both genders be present in a game be an aversion, the uninformed might ask? Because of the well over one hundred characters that have appeared in Touhou, no humanoid male has ever appeared on-screen, and the rare sentient male was a talking turtle or cloud. Apparently, in spite of having just as many male monsters as females, they just never decide to do anything.
 * Note, however, that Rinnosuke, a half-youkai, appears in one of the supplementary works.
 * Left 4 Dead. Mentioned swiftly in a quote by Zoey where she sounds, not so surprisingly, less than happy. There are of course, many fandom plays on this, including a comic where Zoey has to go from killing Infected to killing men when the Survivors make it to the safe zone. Of course, when applying Fridge Logic, one can realize she isn't the last woman on earth, as we have not only Rochelle, but Amanda Slater, the boat man's wife, but still the joke continues.


 * The backstory of Sword of the Stars describe the Morrigi as having barely survived through one of these: In Morrigi society, only females spend their whole life planetside while the males live almost entirely on starships. Due to a grueling centuries-long war with an unknown space-faring race, the entire Morrigi starfleet was all but wiped out and left what was left of the species (which wasn't much) with a 10-to-1 female/male ratio.
 * The Syren from Star Control 2 had a mirrored version happening to them: when their entire home planet was suddenly turned into a Lethal Lava Land, the few survivors were the species' budding space force... Which was overwhelmingly female.
 * The obscure PC game Gender Wars had the men and women of the world square off in a fight to the death as independent nations. The implications are lampshaded in the first mission for each side, where the goal is to steal stored reproductive material from an enemy base.

Web Comics

 * Angels 2200. A major plot point is whether the plague affected the rebel colonies as well. While Angels 2200 has no prominent male character, the gender imbalance does serve for general Fan Service, in the form of an endless supply of busty action girls in Stripperific latex space suits, in particular an Amazon Brigade of shapely beauties.
 * The first story arc of The Dragon Doctors has them investigating a valley where men can't exist--if any go in there, they become permanently female, so the population of the valley is effectively suffering from this trope despite nobody technically dying.

Web Original

 * One DnD story posted on /tg/ featured a sociopathic, misandrist tiefling bard swaying an elven queen into almost doing this. Before being killed by the party's (male) barbarian and (female) fighter.
 * The Flash-animated series Gotham Girls had a large section of episodes where all men in the city simply vanished and ceased to exist due to some sort of strange mad science. Very fortunately, they were all brought back unharmed by the device as well. There are a few interesting implications of this; the police force loses the majority of its members due to cops being male-dominated, but the violent criminals were even more male-dominated, so there are less people for them to police. There's also a sub-plot about a missing female detective--turns out, she was secretly a Transsexualism and also vanished with the rest of the men.

Western Animation

 * Ember and her cronies succeed in doing this to all the males in Danny Phantom, because one of them was dumped by her boyfriend. They got better, of course.
 * In the Justice League episode "Fury", an Amazon with a serious bent against the male gender decides to release a disease into the atmosphere that nearly kills off all of the men on the planet. This includes the male members of the Justice League (even Superman and the Martian Manhunter are affected, despite not being human, and Solomon Grundy, who is The Undead. It's implied magic is involved). It's up to Wonder Woman and Hawkgirl to save the day (of course, this includes fighting against an all-female alliance of villains).
 * Codename: Kids Next Door has a variant where a female villain develops a way to turn boys into girls and launches a war between the genders. This combined with her tyrannical rule creates a Bad Future where only a few boys remain, led by an aged Numbuh 4. Numbuh 3's Identical Granddaughter winds up teaming up with the boys to prevent it all via Time Travel.

Real Life

 * The Wolbachia bacteria is inside 40-70% of insects and can't be transmitted by bug sperm. So it kills males in their eggs. If a little male critter survives, the bacteria tries to transform it into a female.
 * Some good news for male bugs everywhere. The Blue Moon Butterfly has evolved a resistance to the bacteria and went from males being 10% of the population to 40%. They did it in a year, which is 10 butterfly generations. Start your mutating, males! Survive! Survive!!!
 * Paraguay, after the War of the Triple Alliance. Five years of nonstop war against Argentina, Brazil and Uruguay left about 50% of the prewar population and nearly 90% of the prewar male population dead.
 * Female fetuses are often aborted in some regions of China and northern India, depending on local culture. Where this is impossible, such as in some of China's rural regions, baby girls are sometimes simply murdered as soon as they are born. There are laws against this on the books, but they are either not enforced very rigidly or ineffective at curbing this. The cause is social mores that make male children more valuable -- "girl babies don't count." The Economist magazine wrote that "it is no exaggeration to call this gendercide," adding that the number of women "missing" in this way is well over a hundred million. This has led to increasing criminalization of selective abortion of females, including banning the use of ultrasound for non-medical reasons, but the laws have had limited effect because it's hard to prove the doctor informed a couple of a child's gender. Yin Yin Nwe, Unicef's representative to China, refers the fact that the one-child policy brings many benefits for girls, "but they have to be born first."
 * This results in a social problem for men too: it means that there is a perpetual drought of females for spouses. And unfortunately, this problem is "solved" by trafficking women from other countries who are forced into marriage to these men.
 * Infanticide has a long history in the regions. Back before birth control - i.e., before the twentieth century - one dealt with unwanted children in one of two ways: abortion, which was common virtually worldwide, and getting rid of the baby when it was born. In Europe and its offshoots, this took the form of giving your baby to an orphanage or a guild, or simply to leave them someplace that someone might pick them up. Whether the child lived or died - and at least nine out of ten babies abandoned in this way did die - was irrelevant, because their parents had not, technically, committed infanticide. In the (Indian) Subcontinent and East Asia, they gave them (honourable) death. Of course, there's many a case of parents throughout Eurasia meaning to dispose of their unwanted child, only to find they just can't do it; related to this, there are countless cases of the adoption of unwanted babies by those unable to have (more) children themselves.
 * World War One saw the deaths of ten million soldiers -- all of them male -- and six million civilians. Given equal distribution of civilian casualties by gender, that's over four men killed for every woman. When Europe tried to pick up the pieces after the war was over, they were faced with a plethora of women and a dearth of men.
 * By contrast, World War Two killed approximately sixty million people. Twenty-five million were soldiers (overwhelmingly male), while around thirty-five million were civilians. Again, given equal male and female civilian deaths, that means a little over two men dead per woman.