Asmat is, in its way, a perfect place. Everything you could possibly need is here. It’s teeming with shrimp and crabs and fish and clams. In the jungle there are wild pig, the furry, opossumlike cuscus, and the ostrichlike cassowary. And sago palm, whose pith can be pounded into a white starch and which hosts the larvae of the Capricorn beetle, both key sources of nutrition. The rivers are navigable highways. Crocodiles 15 feet long prowl their banks, and jet-black iguanas sun on uprooted trees. There are flocks of brilliant red-and-green parrots. Hornbills with five-inch beaks and blue necks.

This is an excerpt from Savage Harvest: A Tale of Cannibals, Colonialism and Michael Rockefeller's Tragic Quest for Primitive Art, by Carl Hoffman. Copyright (c) 2014 by Carl Hoffman. To be published on March 18, 2014, by William Morrow, an imprint of HarperCollins Publishers. Reprinted by permission.

And secrets, spirits, laws and customs, born of men and women who have been walled off by ocean, mountains, mud and jungle for longer than anyone knows.

Until 50 years ago, there were no wheels here. No steel or iron, not even any paper. There’s still not a single road or automobile. In its 10,000 square miles, there is but one airstrip, and outside of the main “city” of Agats, there isn’t a single cell tower. Here it’s hard to know where the water begins and the land ends, as the Arafura Sea’s 15-foot tides inundate the coast of southwest New Guinea, an invisible swelling that daily slides into this flat swamp and pushes hard against great outflowing rivers. It is a world of satiny, knee-deep mud and mangrove swamps stretching inland, a great hydroponic terrarium.

We were crossing the mouth of the Betsj River, a turbulent place of incoming tide and outrushing water, when the waves slammed and our 30-foot longboat rolled. I crawled forward, reached under a plastic tarp and fumbled blindly in my duffel for the Ziploc bag holding my satellite phone, and slipped it into my pocket. I hadn’t wanted to bring the phone, but at the last minute I’d thought how stupid it would be to die for want of a call. If Michael Rockefeller had had a radio when his catamaran overturned in this exact spot in 1961, he never would have disappeared.

He was 23 years old, the privileged son of New York Gov. Nelson Rockefeller, seven months into the adventure of a lifetime that had transformed him from clean-cut student to bearded photographer and art collector. One moment his boat was being tossed by the waves, just as ours was, and the next he and his Dutch companion were clinging to an overturned hull. And then Rockefeller had swum for shore and vanished. No trace of him was ever found, despite a two-week search involving ships, airplanes, helicopters and thousands of locals prowling the coasts and jungle swamps. The fact that such a simple, banal thing had happened to him made what was happening to us feel all the more real. There would be no foreboding music. One bad wave and I’d be clinging to a boat in the middle of nowhere.

The official cause of Michael’s death was drowning, but there had long been a multitude of rumors. He’d been kidnapped and kept prisoner. He’d gone native and was hiding out in the jungle. He’d been consumed by sharks. He’d made it to shore, only to be killed and eaten by the local Asmat headhunters. The story had grown, become mythical. There had been an off-Broadway play about him, a novel, a rock song, even a television show in the 1980s hosted by Leonard Nimoy.

I’d been fascinated with the story ever since I first saw a photo of Michael on his first trip to what was then called Netherlands New Guinea. In it he is kneeling, holding his 35-millimeter camera under the close eyes of natives. He was working on a documentary film in the highlands of the Great Baliem Valley. That film, Dead Birds, was a groundbreaking ethnographic examination of a barely contacted, stone-age culture that engaged in constant ritual warfare. The mountains, the mist, the naked men yelling and screaming and attacking one another with spears and bow and arrow, had fascinated and entranced me, as had the whole idea of contact between people from dramatically different worlds. In my 20s, I’d tried to get there, but it was too expensive for my young budget, so instead I’d ended up, briefly, in Borneo.

I spent hours looking at that photo, wondering what Michael had seen and felt, wondering what had really happened to him, wondering if I might be able to solve the mystery. That he had been kidnapped or had run away didn’t make sense. If he had drowned, well, that was that. Except he’d been attached to flotation aids. As for sharks, they rarely attacked men in these waters and no trace of him had been found. Which meant that if he hadn’t perished during his swim, there had to be more.

There had to have been some collision, some colossal misunderstanding. The Asmat people were warriors drenched in blood, but Dutch colonial authorities and missionaries had already been in the area for almost a decade by the time Michael disappeared, and the Asmat had never killed a white. If he had been murdered, it struck to the heart of a clash between Westerners and Others that had been ongoing ever since Columbus first sailed to the New World. I found it compelling that in this remote corner of the world the Rockefellers and their power and money had been impotent, had come up with nothing. How was that even possible?

I started poking around in Dutch colonial archives and the records of Dutch missionaries, and I found more than I’d ever imagined. After the ships and planes and helicopters had gone home, a series of new investigations took place. There were pages and pages of reports, cables and letters discussing the case, sent by the Dutch government, Asmat-speaking missionaries on the ground and Catholic Church authorities—and most of it had never been made public. Men who had been key participants in those investigations had remained silent for 50 years, but they were still alive and finally willing to talk.

***

On February 20, 1957, in a city of concrete and steel 6,000 times bigger than the largest hamlet in Asmat, Nelson Rockefeller introduced the world to a new kind of seeing. He was 49 years old, square-jawed and ambitious, the grandson of Standard Oil founder John D. Rockefeller. At the time of Nelson’s birth, which was announced on the front page of the New York Times, John D. was the richest man on earth, with a fortune estimated at $900 million. In two years, Nelson would become the governor of New York. In 1960, he would run for the presidency. In 1974, he would become vice president of the United States.

Inside a family-owned, four-story townhouse with elegantly curving bay windows at 15 West 54th Street—just around the corner from the Museum of Modern Art, which his mother, Abby Aldrich Rockefeller, had helped found—guests began arriving at 8:30 p.m. to a private reception heralding the first exhibit of the Museum of Primitive Art, which would open to the public the following day. The things they were celebrating came from a world away. A carved paddle from Easter Island. The elongated, exaggerated face of a wooden mask from Nigeria. Pre-Columbian Aztec and Mayan stone figures from Mexico. Around these objects were no ethnographic dioramas, no depictions of African huts or canoes and fishing nets. They rested atop stark white cylinders and cubes, illuminated by track lighting against white walls. They were to be viewed as works of art.

Nelson was dressed in the height of New York tribal finery: black tie. As the guests nibbled canapés and sipped wine, he told them that his new museum was “the first...of its kind in the world”—dedicated exclusively to primitive art. “We do not want to establish primitive art as a separate kind of category,” he said, “but rather to integrate it, with all its missing variety, into what is already known to the arts of man. Our aim will always be to select objects of outstanding beauty whose rare quality is the equal of works shown in other museums of art throughout the world, and to exhibit them so that everyone may enjoy them in the fullest measure.”

Michael Rockefeller was just 18 years old that night, and it’s easy to imagine the power the event had for him. His father’s pride over the new museum, the exotic beauty and pull of the objects, the cream of New York’s elite admiring them. Michael was tall and slender, clean-shaven and square-jawed like his father, with thick, black-rimmed glasses. He’d grown up with his two sisters and two brothers in the family townhouse in Manhattan and on the Rockefeller estate in Westchester County. As Abby Rockefeller had done with Nelson, so Nelson did with Michael, schooling him in art the way other boys were schooled in baseball, taking him to art dealers on Saturday afternoons. His twin sister, Mary, remembered how they loved to watch their father rearrange his art.

As he neared the end of his four years at Harvard, Michael was, in the words of a friend, “a quiet, artistic spirit.” And he was torn. His father expected his son to be like him—to pursue a career in one of the family enterprises, banking or finance, and indulge his artistic passions on the side. Michael graduated cum laude from Harvard with a B.A. in history and economics, but he yearned for something else. He’d traveled widely, working on his father’s ranch in Venezuela for a summer, visiting Japan in 1957, and he’d been surrounded not just by art, but by primitive art. And how could he make his “primitive art”-collecting father prouder than by going to its source and plunging in deeper than the forceful governor and presidential candidate had ever dreamed?

At Harvard he met the filmmaker Robert Gardner, who was beginning work on Dead Birds, and signed on as the sound engineer. “Mike was very quiet and very modest,” said Karl Heider, who as a Harvard graduate student in anthropology had shared a tent on the 1961 film expedition with him. In the evenings, Heider was astonished to see the wealthiest member of the team darning his socks.

But Michael was ambitious, too. “Michael’s father had put him on the board of his museum,” Heider told me, “and Michael said he wanted to do something that hadn’t been done before and to bring a major collection to New York.” He had already corresponded with Adrian Gerbrands, deputy director of the Dutch National Museum of Ethnology, who’d recently begun fieldwork in Asmat. The region was home to people who lived as hunter-gatherers and yet produced carvings of astounding beauty. “Asmat,” Heider said, “was the obvious choice.”

Michael made a scouting trip there during a mid-May break in filming. Only in the mid-1950s had a few Dutch missionaries and government officials begun pacifying the Asmat, but even by 1961 many had never seen a Westerner, and inter-village warfare and headhunting remained common. “Now this is wild and somehow more remote country than what I have ever seen before,” Michael wrote. In many ways, the Asmat world at the time was a mirror image of every taboo of the West. In some areas, men had sex with each other. They occasionally shared wives. In bonding rituals, they sometimes drank one another’s urine. They killed their neighbors, and they hunted human heads and ate human flesh.

They weren’t savages, however, but biologically modern men with all the brainpower and manual dexterity necessary to fly a 747, with a language so complex it had 17 tenses, whose isolated universe of trees, ocean, river and swamp constituted their whole experience. They were pure subsistence hunter-gatherers who lived in a world of spirits—spirits in the rattan and in the mangrove and sago trees, in the whirlpools, in their own fingers and noses. Every villager could see them, talk to them. There was their world, and there was the kingdom of the ancestors across the seas, known as Safan, and an in-between world, and all were equally real. No death just happened; even sickness came at the hand of the spirits because the spirits of the dead person were jealous of the living and wanted to linger and cause mischief. The Asmat lived in a dualistic world of extremes, of life and death, where one balanced the other. Only through elaborate sacred feasts and ceremonies and reciprocal violence could sickness and death be kept in check by appeasing and chasing those ancestors back to Safan, back to the land beyond the sea.

Expert woodcarvers in a land without stone, the Asmat crafted ornate shields, paddles, drums, canoes and ancestor poles, called bisj, embodying the spirit of an ancestor. The bisj poles were 20-foot-high masterpieces of stacked men interwoven with crocodiles and praying mantises and other symbols of headhunting. The poles were haunting, expressive, alive, and each carried an ancestor’s name. The carvings were memorial signs to the dead, and to the living, that their deaths had not been forgotten, that the responsibility to avenge them was still alive.

The Asmat saw themselves in the trees—just as a man had feet and legs and arms and a head, so did the sago tree, which had roots and branches and a fruit, a seed on top. Just as the fruit of the sago tree nourished new trees, so the fruit of men, their heads, nourished young men. They all knew some version of the story of the first brothers in the world, one of the Asmat creation myths, in which the older brother cajoles the younger into killing him and placing his head against the groin of a young man. The skull nourishes the initiate’s growth, even as he takes the victim’s name and becomes him. It was through that story that men learned how to headhunt and how to butcher a human body and how to use that skull to make new men from boys and to keep life flowing into the world.

The completion of a bisj pole usually unleashed a new round of raids; revenge was taken and balance restored, new heads obtained—new seeds to nourish the growth of boys into men—and the blood of the victims rubbed into the pole. The spirit in the pole was made complete. The villagers then engaged in sex, and the poles were left to rot in the sago fields, fertilizing the sago and completing the cycle.

Anything outside of the tangible immediacy of what the Asmats could see had to come from that spirit world—it was the only comprehensible explanation. An airplane was opndettaji—a passing-over-canoe-of-the-spirits. White men came from the land beyond the sea, the same place the spirits lived, and so must be super beings.

Michael did not plunge into this realm a lone adventurer; he was a Rockefeller, not to mention a trustee of the Museum of Primitive Art. His traveling party included, among others, Gerbrands and René Wassing, a government anthropologist assigned to him from the Dutch New Guinea Department of Native Affairs.

Michael’s field notes from his first trip to Asmat and the letters he wrote reveal a deepening seriousness regarding his collecting. Before his second expedition, he laid out “objectives; themes of investigation; criterion for stylistic variation.” He wanted to produce books and mount the biggest exhibition of Asmat art ever.

Michael returned to Asmat in October 1961. Wassing joined him again and in Agats he badgered a Dutch patrol officer into selling him his homemade catamaran, into which Michael stuffed a wealth of barter goods—steel axes, fishing hooks and line, cloth and tobacco, to which the Asmats had become addicted. He and Wassing, accompanied by two Asmat teenagers, visited 13 villages over three weeks.

Michael collected everywhere he went and in quantity, loading up on drums, bowls, bamboo horns, spears, paddles, shields. He was most impressed by the bisj poles. With no sense of irony, he wrote: “This was one kind of object that seemed to me inviolate for the encroachment of western commercialism upon Asmat art.” In the southern village of Omadesep he’d bought a set of four on his first trip; they now stand in the Michael C. Rockefeller Wing of the Metropolitan Museum of Art, which absorbed the collections of the Museum of Primitive Art after it closed in 1976.