In the earliest American comic books of the 1930s, female characters generally took supporting roles. To the muscle-bound male superheroes, they were the obedient sidekicks (Hawkgirl, Bulletgirl) or the hapless girlfriends constantly in need of rescue (Lois Lane). The scarce few female superheroes around ended up with the feeblest of foes and storylines (the exploits of the Invisible Scarlet O’Neil became progressively less heroic and more soap-operatic) or had fancy monikers (The Woman in Red, Miss Fury) but no actual superpowers.

Then, literally out of the sky, arrived Wonder Woman. An actual female superhero with actual superpowers, she had the beauty of Aphrodite, the wisdom of Athena, the strength of Hercules, the speed of Mercury, and the unparalleled attention of a hitherto untapped female readership.

“She was the only hero that made you feel good about yourself,” as women’s rights trailblazer Gloria Steinem said. In the 1970s, Steinem chose Wonder Woman as cover girl for the inaugural issue of women’s magazine Ms., and helped establish Wonder Woman’s status as a perennial feminist icon.

In her new book The Secret History of Wonder Woman, historian Jill Lepore makes the case that the connection between Wonder Woman and feminism is even more intrinsic than previously thought. Just as Superman was forged out of science fiction tropes and Batman emerged from the shadows of detective noir fiction, Lepore shows that Wonder Woman sprang directly and overtly, unitard and all, from feminist ideology and storytelling.

“The backstory assigned to Wonder Woman is that she’s created by her mother out of clay, in a matriarchal Amazonian society where women live eternally in a paradise without war,” says Lepore. “It borrows entirely from feminist utopian fiction of the 1910s written by authors like Charlotte Perkins. But because feminist utopian fiction is less well known, no one understands it comes from there.”

Muddy fictitious origins aside, Wonder Woman’s real-life creator was William Moulton Marston. In his professional life, he was a Harvard-trained psychologist who invented the polygraph and campaigned for its use in courtrooms. And, in his personal life, he was uncommonly close with some uncommon women. Marston lived in a polyamorous relationship with his wife Elizabeth Marston and mistress Olive Byrne. Olive was a former pupil of Marston’s and the niece of Margaret Sanger, the Planned Parenthood advocate who coined the term ‘birth control’ and cofounded America’s first birth control clinic. “No woman can call herself free who does not own and control her own body,” Sanger wrote. Olive’s mother Ethel, the other cofounder of the clinic, was arrested and nearly died protesting her own imprisonment with a hunger strike.

Clearly, Marston witnessed the feminist, suffrage and birth control movements of the early part of the twentieth century from an intimate vantage point. So in 1941, when he was hired by publisher MC Gaines to come up with a remedy to America’s moral panic over comic books – Batman had lately been wielding a gun, and it had even been suggested that the idolisation of Superman’s powers verged on fascistic – he suggested, in his words, “a feminine character with all the strength of Superman plus all the allure of a good and beautiful woman.”

“Marston’s argument was that you can fight fascism with feminism,” says Lepore. “You can see the influence of watching the women in his life on his political imagination.”

With the Lasso of Truth as her signature weapon – a mystical version of Marston’s polygraph – Wonder Woman made her debut in late 1941. She was an instant hit, providing a refreshing alternative to the knock ‘em, sock’em violence traditionally expected of comic book superheroics. Marston infused the comics with what he saw as the inherently feminine qualities of love, compassion and wisdom.

The character did, however, spend an astonishing amount of time bound up in chains. Marston’s symbolic point was that Wonder Woman would ultimately break free, of course – but there was increasing concern that the abundance of bondage imagery in the comic (gimp masks and spanking were also involved) was downright kinky.

“Marston wanted her to be an allegory for the emancipation of women,” Lepore says. “He said, again and again, that Wonder Woman had to be constrained so that she could break free. But there were many people, including Gaines, who thought that it just looked like bondage.”

The fact that, years prior, Marstson had engaged in robust research into the psychology of sexual submission and domination, suggests that he was indeed indulging something of a fascination, if not a fetish.

“I think what’s so interesting is that, really, it’s plainly both those things,” says Lepore. “It’s a complicated legacy.”

Some would say a contradictory legacy. Even as Wonder Woman was being embraced as a feminist figure, actress Lynda Carter, who played the character in the ‘70s television series, objected strongly to her own status as a sex object.

Lepore suggests that Wonder Woman is the symptom of a culture eager to represent women’s power as sexual. “Maybe audiences are more comfortable with women wielding sexual power than wielding actual political power. Wonder Woman was explicitly the embodiment of women’s political power, coming from the land of Amazons to the US to fight for democracy and women’s rights – and yet she had to do all that dressed like a pin-up girl.

“But what’s important to me in looking at this in trying to recover this lost chapter in the history of women’s rights is to acknowledge, yeah, there is a lot of kink in Wonder Woman, and she does look like that, but so much of her representation and her plot lines are inspired by the political struggles that women had been waging for decades.”

In the struggle for Hollywood blockbuster screen time, audiences are starting to see superssisters doing it for themselves. Marvel Comics’ hammer-wielding Thor has been recast as a woman, Scarlett Johansson’s Black Widow is genuinely kicking butt beside Captain America, and Marvel has finally announced that their first new movie with a lead female superhero, Captain Marvel, is in the works.

Wonder Woman herself will make her comeback in 2016, in Zack Snyder’s Batman v Superman, with more films and a possible TV series slated after that. She’s to be played by Israeli model and actress Gal Gadot, who spent two years in the Israel army and starred in the Fast and Furious franchise. (Her signature quote in those films was, “You don’t send a man to do a woman’s job.”)

Worryingly, Wonder Woman’s origin story, and its feminist subtext, may not make the cut. In 2011, when the comic book character got a gritty reboot, the story turned, if anything, fundamentally anti-feminist: the peaceful Amazons were reimagined as man-slaying sirens, while Wonder Woman herself became the daughter of the immortal womaniser Zeus rather than a literal gift of the gods. So far, it appears the new movie is taking its lead from the revamped version.

“That’s like reinventing the story of Superman’s origins and saying, we don’t need the Krypton thing – let’s actually have him come from Kansas. There’s a casual casting aside of the feminist origins of Wonder Woman. It’s been intentionally erased.”

It would seem that even after more than sixty years, in an unfortunate twist on that old superhero prerequisite, Wonder Woman’s secret identity remains largely secret.

“There’s definitely more to her than we see.”

This article originally appeared in the Sydney Morning Herald in November 2014.