This July, the 49th Tarzan movie will come swinging into theaters. Alexander Skarsgard is the latest actor to don the loincloth, and the new adaptation—a big-budget Warner Bros film called Legend of Tarzan—revives a franchise that dates all the way back to silent film, radio, and Edgar Rice Burroughs’s pulp novels that kicked it all off in 1912. And while the appetite for tales about the Lord of the Apes has diminished in recent years (Disney's 1999 animated version was the last theatrical release), for about four decades, U.S. audiences could expect to see a new Tarzan movie every year. (Take that, Avatar.)

What drove this Tarzan mania? Although the series was designed to appeal to young men who wanted to run away from society, rip off their clothes, and climb trees, it also had a second audience, a female one that gazed dreamily at this disrobed alpha male and relished the then-rare opportunity to admire and sexualize him. Women's sexuality was either ignored or viewed as problematic when Burroughs was publishing his stories, and diagnoses of nymphomania were on the rise. (The supposed symptoms included women flirting, having orgasms, or feeling more passionate than their husbands about sex.)

The reality is that women's sexual appetites are equal to men’s, a fact that has been confirmed by science repeatedly in recent years. But in 1912, when the Tarzan stories debuted, the female libido was generally denied, suppressed, and vilified, and it had few outlets for expression.

Tarzan was one of those few. There were other channels, of course, but none on his level. When Burroughs’s work was released, women's main romantic and sexual resources were novels centered around the marriage plot, such as works by Jane Austen, the Bronte sisters, and George Eliot. And while works like Pride and Prejudice are literary accomplishments, they focus on the romantic and protective aspects of love and lack any sort of deeper carnal desire. The mass-produced escapist novels that most of us consider “romance novels,” which offer a much stronger sexual component, would not come into being until the 1930s. Romance publisher Harlequin wasn’t even founded until 1949. (Note that Harlequin's rise coincides with a drop in the Tarzan craze.)

Unlike marriage-plot novels, Burroughs's writing doesn't shy away from Tarzan’s carnal and physical allure. He is described as a “war-like figure” with “black hair falling to his shoulders behind and cut with his hunting knife to a rude bang upon his forehead… He has 'a straight and perfect figure, muscled as the best of the ancient Roman gladiators must have been muscled, and yet with the soft and sinuous curves of a Greek god.” The reader can almost hear Burroughs saying, “hubba hubba!”. Compare that to Austen’s description of Fitzwilliam Darcy (a.k.a. Mr. Darcy), upheld to this day as a romantic ideal for women: ”[He] soon drew the attention of the room by his fine, tall person, handsome features, noble mien; and the report which was in general circulation within five minutes after his entrance, of his having ten thousand a year. The gentlemen pronounced him to be a fine figure of a man, the ladies declared he was much handsomer than Mr. Bingley.” There's little described here physically aside from the vague “fine figure” of his body, and more words are devoted to his wealth and class than to his looks.

Hollywood did offer Douglas Fairbanks, Rudolph Valentino, and Ramon Novarro, who each provided swashbuckling swagger for female viewers. Their coy looks in three-piece suits gave off a few sparks. But this was mere playground flirtation compared to Tarzan: His near-nude appearance, sweat-glistening body, physical means of communication, and constant flexing was sexual napalm to straight women, and this erotic detonation would have had few rivals. MGM shifted its marketing to capitalize on the movies’ main appeal. Advertising revealed this by trumpeting, “Girls! Would you live like Eve if you found the right Adam? Modern marriages could learn plenty from this drama of primitive jungle mating! If all marriages were based on the primitive mating instinct, it would be a better world.”

Burroughs maintained his focus on the physical when his books became films. He was concerned about the physique of the star who would play Tarzan. In a letter he wrote to Hollywood film producers, he insisted, “Tarzan must be young and handsome with an extremely masculine face and manner. Then he must be the epitome of grace… My conception of him is a man a little over six feet tall and built more like a panther than an elephant.” Later film versions would star Johnny Weissmuller, a former Olympic swimmer. Weissmuller's Tarzan movies hit their stride during World War II, when men were on the front lines and women were the primary moviegoers.

The racial bias of these stories can’t be overlooked. Tarzan is often seen as a bootleg version of Rudyard Kipling's The Jungle Book, which predated Burroughs's novels. Indeed, characters in both share the same origin story: A child is abandoned in the jungle, left to be raised by wild animals. But Tarzan is a white man of British nobility, while Kipling's Mowgli is Indian. In a 2014 speech, Harry Belafonte recalled watching a 1935 Tarzan film in a Harlem theater at age eight. The image was clear:

“This porcelain Adonis, this white liberator, who could speak no language, swinging from tree to tree, saving Africa from the tragedy of destruction by a black indigenous population of inept, ignorant, void-of-any-skills [people], governed by ancient superstitions with no heart for Christian charity. Through this film the virus of racial inferiority —of never wanting to be identified with anything African—swept into the psyche of its youthful observers.“

As historian Tony Warner has pointed out, Tarzan is a symbol of colonialism:

“The story charts the life of an aristocratic offspring of Lord Greystoke, who is orphaned as a child in Africa, raised by apes in the jungle, and soon becomes the King of that jungle and all who dwell in it. Tarzan, which means white skin in 'ape speak,' is faster, stronger, and more intelligent than the native Africans. For readers at the time and perhaps even now, whiteness equals civilisation.”

Tarzan being a white man not only reinforced racial stereotypes, but it also allowed white women to fantasize about a man with the racist signifiers of a person of color without crossing racial lines. When the first books were published, and even when many of the early movies were released, interracial marriage was still illegal in the United States But Hollywood liked to flirt with this taboo. One of the most famous examples is Valentino's 1921 film The Sheik, in which Valentino plays an Arabian ladies’ man. It was a box office smash hit. Tarzan advertising winked at this as well: “Could you ever be coaxed back to civilization as long as you had a bronzed mate like this to kiss you awake at every dawn?” one line went—the word “bronzed” hinting at Tarzan being perceived as non-white.

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Tarzan’s appeal also has a class component: He’s both an English lord by birth and a wild man living off the land. That makes him an object of fantasy at either extreme—both Prince Charming and penniless rebel. It also makes him accessible to anyone in any point along the class spectrum, especially considering the American Everywoman, Jane, who represents the film's female audience. To underline the point, the Tarzan himself rejects these societal divisions as artificial. Once his royal lineage is discovered, he doesn’t cloister himself in the upper classes as his fellow nobles did, but continues being a man of the world.

Margot Robbie as Jane and Alexander Skarsgard as Tarzan in the upcoming Legend of Tarzan film.

Tarzan was meant to be a romantic character—in the books and films, he possesses romantic qualities that are surprising given his otherwise macho persona. It is the combination of these traits that render Tarzan the ideal, if implausible, romantic fantasy for women, a hybrid of the mannered Mr. Darcy and the fierce, wild man. This crossover made him a secure yet sexual person onto which women could project their desires. Women also fell for Tarzan because of what he didn’t do—namely, hit Jane. Throughout the narrative, Tarzan is never violent toward women. In that era, some courts were still upholding a man’s right to beat his wife. And in multiple films during Tarzan's most popular period, men would slap or spank their wives, often to rein in female “hysteria” or put women in their place. But “savage” Tarzan never raises a hand to Jane.

The portrayal of Jane bolstered the appeal of the Tarzan story to women. In both book and film versions, Jane is a woman of action, meeting Tarzan on his own turf. She's often depicted as an adventuress—this in 1912, seven years before women had the right to vote. Jane slashes her way through the underbrush of Africa at a time when few women would have had access to male-only spaces (many dining clubs and bars at the time were segregated by gender). True, Jane was frequently the archetypal damsel in distress, but these moments serve mainly as plot devices to give the romantic leads opportunities to meet.

Their romance begins when Tarzan sees Jane from a distance and falls passionately in love with her at first sight. This struck-by-cupid’s-arrow cliché moment is something more in line with the actions of a Disney princess than a feral jungle-man, but this gender reversal establishes a level of commitment from Tarzan right from the get-go. That commitment is deepened by his monogamy. Throughout the books and the films,Tarzan is tempted by other women, but he remains faithful to Jane. He also longs to marry Jane (and does in the books and some film versions) despite inhabiting a world where that institution would have little to no value.

Samuel L. Jackson plays Civil War veteran and writer George Washington Williams in Legend of Tarzan.

The notions of fidelity and marriage spoke to the women of that era loudly. During World War I, when the Tarzan novels were gaining popularity, many men were fighting overseas, and it was a boom time for prostitution. The U.S. Army banned its soldiers from visiting brothels. Divorce rates were also on a steady rise from 1912 through 1945 despite the fact that divorce wasn't legal throughout the United States, Certain states created “divorce mills” or pop-up camps, and people traveled to them to secure marital separations. All the downsides of both divorce and infidelity fell on women, including incredible stigma. So it follows that they could only lose themselves in the Tarzan fantasy if he was prone to uphold monogamy.

Today, Tarzan lust is even more overt and accepted—just witness the way Alexander Skarsgard broke the internet with his abs—but it's also less striking. Film is now in a post-Magic Mike world where a woman's sexual gaze is being acknowledged and aggressively pursued by Hollywood. Earlier versions of Tarzan were a happy accident: a male adventure yarn that dovetailed with all the untapped sexual desire that women felt from 1912 through the ‘40s. Primatologist Jane Goodall said that she fell in love with Tarzan when she was a young girl and longed to marry him. She would have had a lot of company.

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