When historical novelist Robin Maxwell was looking for a book idea a couple of years ago, her husband asked who her new “literary lovers” would be.

“ ‘Tarzan and Jane!’ just blurted out of my mouth,” she says, laughing at how forcefully the idea seized her. “It was like lava from a dormant volcano.”

And so, 100 years after the Lord of the Apes first swung into the world’s pop culture window, there is “Jane: The Woman Who Loved Tarzan,” a lush, romantic take on the English lord raised by primates — told from Jane’s point of view.

“We’re calling it ‘50 Shades of Green,’ ” Maxwell says.

This is just one leaf on the vine, however. A century after his birth, Tarzan is affixed as one of literature’s most enduring creations. Edgar Rice Burroughs’s archetype of primordial man in an atavistic jungle, more trusting of nature than mankind, struck a chord that still resonates. He is free of religion, politics, nationality and any of the oppressive rules, regulations, oversights, traffic cameras, parking tickets and other indignities imposed on modern man.

Tarzan of the Apes,” an 80,000-word ad­ven­ture about an orphaned boy in the jungle, was a wild sensation when it debuted in the October 1912 edition of The All-Story Magazine. Published in book form in 1914, it spawned a series of 24 novels (and two for teens), selling an estimated 100 million copies in at least 35 languages. It is recognized by the Library of Congress as one of the “Books That Shaped America.” It has been turned into 52 authorized films, a radio show, a comic strip, a Broadway musical, merchandising without end, and even Tarzana, a city in California centered around Burroughs’s property.

To mark the anniversary this year, there’s even more: “Tarzan: the Centennial Celebration,” a hefty coffee-table book covering art, movies and stories; numerous conferences, including the “Tarzan Centennial Conference,” Nov. 1-4 at Bridgewater College in Bridgewater, Va.; a documentary about the first Tarzan film (“Tarzan of the Louisiana Jungle”); a German stop-motion animated feature. Warner Brothers has picked up the option for another Tarzan flick, according to the Burroughs estate, 80 years after Olympic swimming gold medalist Johnny Weissmuller portrayed him.

Globally, there are new editions of Burroughs novels (“The Return of Tarzan,” “The Beasts of Tarzan,” “The Son of Tarzan,” etc.) coming out in at least a dozen countries. This isn’t new. Post-Czarist Russia printed so many pirated copies that a Moscow publisher told the New York Times in 1924: “They read it in offices, read it in street cars, read it in trains, read it in factories. Go to the villages and you find the educated young soldier reading ‘Tarzan’ to a circle of peasants with mouths agape.”

Gore Vidal, in 1963, on the prevalence of Tarzan in this country: “There is hardly an American male of my generation who has not at one time or another tried to master the victory cry of the great ape as it issued from the androgynous chest of Johnny Weissmuller.”

Take your pick of what the ape man represents: Unfettered freedom? Domain over one’s environment? Raw male sexuality? The original Warrior in a State of Nature?

It doesn’t matter. As Maxwell put it in a recent essay, Tarzan never dies.

“I would say it’s because he’s selfless,” says Jim Sullos, president of Edgar Rice Burroughs Inc., the family-run business that manages the late author’s estate, when asked to explain the enduring appeal. “Tarzan is not greedy. He doesn’t want anything from anybody, he doesn’t need anything from anybody. He’s not trying to be in charge, but people want him to be. He lives without rules or restrictions but does so in an honorable way. . . .He represents a freedom we just don’t have anymore.”

In the world of fiction, Tarzan sprang to life more than a century after Robinson Crusoe was shipwrecked, about 20 years after Mowgli was raised by wolves in “The Jungle Book,” and about a dozen years after Joseph’s Conrad’s “Heart of Darkness” immortalized the cruelties and mysteries of Central Africa. Superheroes would not exist for two more decades.

In the less attractive real world, Tarzan came to be in the Age of Adventure. The European powers had, a few decades earlier, swarmed over Africa in a colonial rush. H.M. Stanley’s expeditions and David Livingstone’s African adventures were regarded as heroism defined. Robert Falcon Scott searched for the South Pole to disastrous ends. T.E. Lawrence was exploring architecture in the Middle East but was not yet Lawrence of Arabia. Howard Carter was in Egypt but had yet to find the tomb of King Tut.

In this era, when vast parts of the globe were unknown to Western readers, Eddie Burroughs spent a lot of time thinking about the worlds he hadn’t seen.

Born in 1875 to a well-to-do Chicago businessman, he was expelled from prep school and graduated from a military academy but didn’t qualify for West Point. He joined Custer’s old unit in the U.S. Army but lasted less than a year. Teddy Roosevelt rejected him as a recruit for the Rough Riders.

He kicked around out west, where a gold-mining operation went bust. Running a stationery store in Idaho didn’t last, and neither did a stint as a railroad cop in Utah. Back in Chicago, he tried selling patent medicine and managing stenographers at Sears, Roebuck and Co.

A few years later, Burroughs was suddenly in his mid-30s and pawning his wife’s jewelry for cash.

And then — there’s always a “and then” in these kinds of stories — he was reading a pulp magazine, checking to see whether his company’s ads were correctly placed. He thought the magazine’s stories were so lousy that even he could write better.

So he sat down and wrote a science-fiction piece, “Under the Moons of Mars,” and sold it to All-Story. (Today, you know this tale as “John Carter,” the Disney film from earlier this year.)

He sold it for $400, roughly the modern equivalent of $9,300. This got his attention.

“I was not writing because of any urge to write nor for any particular love of writing. I was writing because I had a wife and two babies,” he later told an interviewer. “I loathed poverty and I would have liked to put my hands on the party who said that poverty is an honorable estate.”

Intrigued by his dabblings in science and by Darwin’s theory on evolution, Burroughs wrote another story for the magazine: A yarn about a British couple, Lord Greystoke and Lady Alice, on an ill-fated sailing trip to Africa. They perish, leaving behind a son, John Clayton, who is taken in by a tribe of apes, the Mangani. These apes, it turns out, are something like Darwin’s missing link — they have a language and a structured society.

John Clayton becomes Tarzan, and Tarzan becomes the tribe’s head honcho, by dint of his courage, honesty, strength and bravery. Later on, he encounters Jane — there’s always a “Jane” in these kinds of stories — and what do you know, she’s from Baltimore!

The book ends (spoiler alert) with her going back to the family summer home in Wisconsin. Tarzan follows her, there’s a house fire, he goes leaping through the trees in Wisconsin (don’t get picky) to save her and then nobly decides to leave her and her fiance to their happiness.

Readers went wild.

“It was a huge hit, right from the beginning,” says Scott Tracy Griffin, author of “Tarzan: The Centennial Celebration.”

Burroughs recognized a cash cow when he saw one, churning out one Tarzan book after another. He incorporated himself as a writer and trademarked Tarzan, the character. The latter was a particularly brilliant move because copyrights expire, but trademarks do not.

“He was always thinking of how to capitalize on [Tarzan] in every new medium that developed,” Griffin says. “When radio came, Tarzan became one of the first prerecorded radio shows. Then it was the first big Sunday ad­ven­ture comic strip, and that helped launch the comic strip industry. And then there were the movies.”

(Trivia: In the early books, Tarzan does not swing from vines. He leaps from tree to tree. Also in the books, he quickly became a sophisticated polyglot; the movies simplified his linguistic skills to nouns and verbs. Hence, “Me Tarzan, you Jane.”)

But the movies were kind to the Tarzan legend. The swimming scene in “Tarzan and his Mate” featured a nude body double for Maureen O’Sullivan, which was considered so shocking that it helped lead to ratings for films. And the movies made stars out of Weissmuller and other men who portrayed Tarzan.

Ron Ely, who portrayed him on television for two years in the 1960s, did his own stunts, was often injured and, for a new generation of fans, was Tarzan personified.

“I was so stamped with the character, that’s the way people saw me, with the parenthetical name — Ron ‘Tarzan’ Ely,” he says now, semi-retired in California, with his third child just graduating from college. “It was certainly limiting. I moved my career to Europe for a while to try to escape it.”

He says that Tarzan, though, is of a particular time and place, and that the efforts to put him in any other period simply don’t work. The Central African jungle took weeks, if not months, to reach in the early 20th century. It was without electricity, a viper-ridden place of peril to outsiders. All of that made Tarzan both more plausible and more intimidating.

“He’s just not a character of this time and age,” Ely says. “He’s a character of 1912. The past 100 years helps us look back to see what things were like then. He’s a snapshot of an era in time.”