Why indigenous languages are dying out in Latin America

When she died last week at the age of 93, Chilean ethnographer Cristina Calderón took with her the Yahgan language. She was, alongside her sister Úrsula — who died in 2005 at 84 — the last full-blooded member of the Yahgan people, an indigenous ethnic group of nomads whose traditional territory includes Chile’s southernmost islands.

Ms. Calderón had been declared a Living Human Treasure by the Chilean government and UNESCO, and her death was mourned by President-elect Gabriel Boric, who takes office on March 11. “When my sister Úrsula passed away I was left alone, with no one to talk to,” Ms. Calderón told El País in 2016. None of her seven children or 14 grandchildren wanted to speak Yaghan.

The now-defunct language had a lexicon of approximately 32,400 words. For comparison’s sake, the average adult English speaker has a vocabulary of around 20,000 words, with a passive vocabulary of around 40,000 words. To prevent the language from disappearing completely, the Calderón family...