Prologue

In 2018, an American missionary and adventurer named John Allen Chau set out to convert the inhabitants of North Sentinel Island to Christianity.¹ The Sentinelese, as they are known to the outside world, are among the world’s most isolated peoples, having lived in voluntary seclusion for thousands of years on their small island in the Bay of Bengal. What the islanders call themselves remains a mystery, as they are so reclusive and hostile toward outsiders that no meaningful communication has ever been established with them.

When Chau approached their shores, the islanders warned him away with bow-fired arrows. Undeterred by this explicit rejection, he persisted in landing on the island. The Sentinelese killed him and buried his body on the beach.

Though the local Indian authorities nominally registered murder charges against “unknown persons,” no serious pursuit of modern procedural justice followed. From one perspective, a kind of natural justice was already served, the same kind of justice served in one of those perennial stories about visitors to zoos who climb into wild animal enclosures and are subsequently mauled. The visitor is the one who should know better, in contrast to the animal that is acting only by instinct.

We can also appreciate the coincidence that the lethal Sentinelese response protected them from a serious existential threat. Though Chau, the zealous Westerner, was just a solitary individual, his body could have introduced pathogens to which the had no immunity, and him establishing sustained contact could have opened the door to further contact and eventually the likely erasure of their way of life. The Sentinelese behaved as if they had all of the facts and were protecting their rational self-interest. But, their knowledge of the history colonization and germ theory being unlikely, we would still ascribe their behavior to an idiosyncratically hostile culture, not subject to rational analysis.

But perhaps there was something at work here other than an unfortunate but avoidable collision between cultures that appear alien to one another? Perhaps the Sentinelese behavior even gives us a glimpse into the behavior of technologically sophisticated humans in the near future, not just the pre-historic past?

The New Earth thought experiment

Let’s consider a thought experiment. Imagine you are in control of a one-way colonization mission to an uninhabited planet that is a near-replica of Earth. You are responsible only for the well-being of your crew, and have no external constraints on crew size nor on the equipment you may bring with you, but are leaving Earth permanently behind. How many people would you take?

Even with a vast, hospitable New Earth to colonize and no crew size restrictions, it seems nearly certain that even with only cursory consideration you would not choose to bring billions, or even millions. You are more likely to take a small number – perhaps only a few thousand (if genetic diversity is accounted for in the planning).

Consider how your small crew would thrive, even with minimal supplies from the home world. If you dispersed yourselves along coastal areas into a federation of small bands, for example, you wouldn’t have to trouble with agriculture, subsisting on nothing but the natural bounty of the land and the sea. A society in the thousands would permit effective governance through direct participation rather than distant representation. Environmental impact would remain manageable without complex regulation. Social cohesion would be sustained by the absence of scarcity and each member’s role being visible and valuable to the community. You could still benefit from modern scientific and technical know-how, but leave behind a vast range of modern technology that in your new context would seem silly, wasteful, or harmful.

The preceding thought experiment gives you full control over whom to bring along. But how would you ever attain such god-like authority? In a less contrived New Earth scenario the many people who would want an opportunity for a fresh start wouldn’t just placidly accept being excluded. While, as we established, taking on additional colonists quickly defeats the less-is-more appeal of the whole mission, you and your select crew, being few, wouldn’t be in the position to say no. Even if you could keep unwanted passengers off your transport, how would you stop others from coming on their own? So the colonization of New Earth would unfold in a very different way than the disciplined mission we originally outlined. It would be a mad race for the best possible position on the new planet. While those with the least to lose by leaving Earth would gain a chance to come out on top, New Earth would eventually end up as crowded and despoiled as the home world.

You would want the mission to be a secret mission, then; you would want to keep the existence of New Earth secret and slip away unnoticed. But once there, you would keep a suspicious eye to the heavens, hoping against the appearance of unwanted Earthlings. Should any one day appear, you would be wise to repel them, no matter how friendly-seeming their overtures, or else more would surely follow.

Let’s return now to the Sentinelese. The essential Sentinelese qualities that emerges from descriptions of them, besides their hostility, are good physical health and discipline. They are muscular, appear well-fed, and their individual members cannot easily be tempted into alliances with outsiders bearing gifts. Both suggest that their group has plenty to go around and that it does go around. Their physical appearance is one obvious sign, but their unwillingness to be bought indicates they aren’t motivated by in-group power struggles to leverage outside resources for advantage over one another.

A reason for their hostility now comes into focus. Perhaps, as the Sentinelese have everything they need, individually and collectively, the outside world has nothing to offer them but the risk of ruin? Their most telling response to would-be visitors is their habit of turning their backs as a group, pantomiming defecation, and retreating to fire arrows. This ritual conveys their assessment of outsiders as nothing but waste.

The Numbers Advantage

Life on New Earth – and, several signs suggest, North Sentinel Island – could be better than ours in every way. Every way but one, that is: having the force of numbers to repel or execute incursions. But this advantage tends to trump all others.

The New Earth mission would die in its crib if it had to build and arm a military big enough to successfully hold off an Earthling invasion. It has to rely on stealth and secrecy, a highly uncertain proposition. Should the cover of secrecy fail and determined Earthlings arrive en masse, the mission would surely be lost; the best the colonists might hope for would be to make a heroic but futile stand.

If the threat to an imaginary and exclusive utopia doesn’t seem compelling, the plight of the flesh-and-blood Sentinelese, whose position is just as precarious, might. Their hostility protects them from the trespasses of tourists, poachers, and missionaries, but from the big, avaricious world they are protected only by the remoteness of their island and external preservation efforts. One can hope they are blissfully unaware of their insecurity. Perhaps they do know and, having everything to lose from capitulation but their lives, stand their ground anyway.

But what if the advantage of numbers could be nullified?

Let’s take the New Earth thought experiment one step further. Imagine that, at the same moment you discovered the habitable new planet with your proprietary telescope, you also identified a planet-destroying asteroid on a collision-course with this one. You need only sneak off to your new planet, as you intended to do in the previous iteration of the thought experiment. But, as they say, in for a penny, in for a pound. What if the heaven-sent asteroid is not quite on a collision course, but you had the means to nudge it onto one?² Finally, why bother with asteroids and interplanetary voyages at all? Your problem with Earth is not with the other Earthlings’ character, just their numbers. If you had a single-shot tool that could wink the bulk of humanity out of existence, you could have your New Earth right here.

We come now to the point of these thought experiments. New technologies are now emerging that could nullify the offensive advantage of numbers – and in particular, AI - surfacing hidden human incentives to dramatically and violently shrink the human population. There has been extensive coverage of the risk of AI-driven human elimination being triggered accidentally, by the emergence of a misaligned superintelligence. But insufficient attention has been paid to the shift in human incentives, or more accurately, the removal of unnoticed constraints, that would make intentional mass human elimination imaginable and likely. This investigation aims to address that critical blind spot in existing discourse on AI risk. For the AI researcher focused on the alignment problem this area may be “out of scope” or a “problem for later,” but not for the average person, for whom the accumulating risks from both misaligned or aligned AI make the distinction merely academic: what difference does it make whether AI eventually destroys everyone, if the last to fall have already used the technology to eliminate the vast majority of humanity?

Continue

1. Details about the Sentinelese, including the incident with John Allen Chau, come from “Sentinelese” on Wikipedia, February 18, 2025. https://en.wikipedia.org/w/index.php?title=Sentinelese&oldid=1276410385. Some relevant primary sources, referenced by the Wikipedia article, include Goodheart, Adam. “The Last Island of the Savages.” The American Scholar 69, no. 4 (2000): 13–44; Pandit, T. N. The Sentinelese. The ASI Andaman and Nicobar Island Tribe Series. Calcutta: Seagull Books on behalf of the Anthropological Survey of India, 1990; and Gettleman, Jeffrey, Hari Kumar, and Kai Schultz. “A Man’s Last Letter Before Being Killed on a Forbidden Island.” The New York Times, November 23, 2018, sec. World. https://www.nytimes.com/2018/11/23/world/asia/andaman-missionary-john-chau.html. ↩

2. The necessity of pre-emptive world-killing will be familar to readers of Cixin Liu’s The Dark Forest. Liu, Cixin. The Dark Forest. Translated by Joel Martinsen. First edition. A Tom Doherty Associates Book. New York: Tor, A Tom Doherty Associates Book, 2015. ↩