On November 17, 2018, when 26-year-old missionary John Allen Chau landed on North Sentinel Island in the Bay of Bengal in the hope of rescuing the natives from “the clutches of Satan,” they predictably slew him. The last tribe living in voluntary isolation in Asia, the Sentinelese kill almost everyone who lands on their shores. The strategy ensures distance from outsiders, protecting them from the diseases and social decay that have felled other tribes of the Andaman archipelago. Now, the attempts to retrieve Chau’s body—in violation of his express wishes—threatens to unleash a cascade of events that would endanger the survival of this island’s exceedingly vulnerable people.

It is hard to overstress how miraculous the continued existence of the Sentinel islanders is. Genetic studies of the contacted Andaman tribes indicate that they directly descend from modern humans who left Africa roughly 60,000 years ago. Traveling eastward along the coastlines of India, these wanderers eventually reached the Andaman Islands—some to stay, others to move further south toward Australia and Papua New Guinea. Intriguingly, the Andamanese may have derived 2 to 3 percent of their genes from an as-yet-unidentified hominin, but otherwise seem to have remained genetically isolated. Their languages constitute a separate language family—Andamanese—although linguist Anvita Abbi holds that it should be subdivided into two other families, Great Andamanese and Ang.

The Andaman islanders were feared by ancient mariners, because they slew anyone who was shipwrecked on their shores. In 1858, repelling bows and arrows with gunfire, British officials established a penal colony on South Andaman Island, now the town of Port Blair. To pacify the hostile natives, the colonizers captured and held some in so-called Andaman Homes. There they were plied with alcohol and other enticements to create “artificial wants,” in the words of one official, to satisfy which they would have to engage in peaceful “intercourse with a superior race.” Also at these homes, guards raped Andamanese women, injecting syphilis into a population that, because of tens of millennia of isolation, had no immunity to the germs that outsiders carry. Epidemics ravaged the Great Andamanese—comprising ten tribes of the South, North and Middle Andaman Islands—slashing their numbers from anywhere between 5,000 and 8,000 people to a mere 19 in the 1960s. By that time, the archipelago had passed to India, which settled the survivors on tiny Strait Island. (See “The Andaman Islanders,” by Sita Venkateswar.)

The Great Andamanese now number about 50 mixed-race individuals. The elders speak a mixture of the 10 original languages, and almost none of the youngsters even that. Most of the men drink. In 2014, I met with Nau, a Great Andamanese woman I had first encountered in the 1990s. She spoke of the desperate loneliness of speaking a language, singing songs and living with memories that she could share with virtually no one. The happiest time in her life, she said, was when as a child she roamed the jungle with her family. “I loved it. We lived free,” she recalled, describing the abundance of the forest and the sheer joy of living in it.

Hunter-gatherers routinely suffer from depression when, their lands usurped by outsiders, they are confined to permanent homes. The Onge of Little Andaman, who were similarly reduced from perhaps 1,000 individuals to roughly 100 at present, are beset with alcoholism and depression. In 2008, eight Onge men and boys died from drinking a liquid that they believed was alcohol; in fact, it was methylated spirit.

Last to succumb were the Jarawa, who live in dense forests on the western edge of South and Middle Andaman Islands and, until 1998, were defending their territory with their lives. They killed settlers who ventured into their territory to fish or hunt game, and got killed in return. That year however, they succumbed to decades of pacification efforts originally developed by Maurice V. Portman, a colonial administrator. Boatloads of Indian officials and anthropologists would land on Jarawa beaches, leave gifts of bananas, red cloth and other goodies from civilization, and retreat. The Jarawa were eventually seduced into laying down their arms and interacting with settlers in peace. Almost instantly, they were beset by epidemics of pneumonia, mumps, measles and other diseases; even the common cold seemed to be lethal to them. No one knows how many died.

The epidemics were eventually controlled, and the Jarawa now number about 450. They call themselves the Ang—meaning “human”—and are linguistically, culturally and genetically closer to the Onge and, probably, to the Sentinelese than to the Great Andamanese. Satellite images show that the Jarawa reserve contains the only undisturbed evergreen rainforest on the Great Andamans—everywhere else, there are settlements, rice fields or degraded forests—and the abundance of its wildlife continues to attract poachers. Some of them ply young Jarawa men with alcohol to induce them to catch and hand over mud crabs, prized in international markets. Creeping alcoholism and sexual exploitation by outsiders are serious concerns, as is the specter of infection with HIV or other dangerous diseases.

The Sentinel Islands have thus far escaped a similar fate. Contact attempts were abandoned in the 1990s, when officials and anthropologists were chastened by the lethal chain of events that the pacification of the Jarawa had precipitated. The island, a mere 60 square kilometers in area, can probably support no more than 100 people. That the Sentinelese and other Andaman islanders thrived for tens of millennia on such small pieces of land speaks not only to the soundness of the voluntary isolation strategy but also to an exquisitely fine-tuned adaptation to the local ecology. The botanical knowledge of the Andamanese is phenomenal. For instance, an Onge man harvests honey by crushing a certain leaf, smearing the paste on his body, and chewing it; when he blows on a hive, the bees fly away, leaving the honey to be collected at leisure. From time to time, Indian scientists announce “discoveries” based on mining their knowledge: a potential cure for malaria, a new species of banana. And not one of the Andamanese is known to have died in the massive tsunami of 2004; having felt the undulations of the earthquake, they knew to flee inland and uphill before the waves arrived.

Moreover, the Onge and Jarawa obeyed taboos, such as against hunting wild boars in the breeding season, that maintained the astonishing abundance of their environs. The Andamanese also seem to have kept population growth down to zero, likely by using natural contraceptives or perhaps even by biological adaptations such as late menstruation and early menopause, observed in the Onge.

For decades, members of civil society, including myself, have striven to ensure that the integrity of the remaining Jarawa and Onge territories and the no-contact policy for the Sentinelese are maintained and enforced. To our consternation, however, a few months ago India’s Home Ministry ordered the lifting of restrictions on foreigners visiting all the islands inhabited by Andaman tribes, including North Sentinel, with the objective of “promoting tourism and overall development” of the islands. Also in the offing for the Andamans and their sister chain, the Nicobar Islands further south, are a railway line through the Jarawa reserve, many new ports, a container terminal and massive naval installations. In the eyes of defense planners in India—a key U.S. ally—the islands are “unsinkable aircraft carriers” to be mobilized in any future confrontation with China. The original inhabitants of the Andaman archipelago seem to find room in these grand visions only as exhibits in an open-air zoo.

Meanwhile, the police are engaging in tense standoffs with the Sentinelese in trying to retrieve Chau’s body from the shore, where they buried it. These efforts can only lead to further fatalities or, even more dangerous in the long run, a renewal of “friendly contact” overtures.

I too approached the island in a boat in 1998, spotting from a distance a canoe in which two figures stood, fishing; others on the beach observed the encounter. Seeing us, the fishers moved back toward their shore, whereupon we left. I regret that visit; even if for some minutes, I violated their privacy and tranquility. Unlike Chau, however, it did not occur to me that I had any wisdom to impart to them. What can I, a representative of a civilization that, within the span of a few hundred years, has destabilized the biosphere of an entire planet, have to offer to a people who have thrived since the dawn of humankind on these tiny islands? Is it we who have something to teach the Sentinelese, or they us?