Want smart analysis of the most important news in your inbox every weekday along with other global reads, interesting ideas and opinions to know? Sign up for the Today’s WorldView newsletter.

On North Sentinel Island, a spit of coral and rock in India’s far-flung Andaman and Nicobar Islands, lives one of the planet’s most isolated groups of people. They are a tribe of hunter-gatherers known as the Sentinelese, a name given to them because no one has any clue what they call themselves. Nor does anyone know how many of them there are; the best guesses put their population at fewer than 100.