Languages abound in South Africa: it has 11 official ones, and dozens of unofficial. But the death on October 7th of Elsie Vaalbooi, aged about 100, saddened linguists. She was one of the last speakers of nlu, a click-based dialect of the once-nomadic San people. Only a handful of her aging relatives can still use nlu, the last known example of !Ui, a family of San languages spoken across southern Africa by hunter-gatherers, possibly for the past 30,000 years. It is now, it seems, about to expire.

According to UNESCO, the UN's cultural body, half the world's 6,000 or so languages could die within a generation. Indigenous, nomadic groups, such as Australia's aborigines (with 400 languages) and southern Africa's San, have rich deposits of old languages. But they are vulnerable as traditional lifestyles die. Of an estimated 1,400 African tongues, 500 are in decline, half of them facing imminent extinction.

Mrs. Vaalbooi had become a campaigner for the San tongues. "I want our language to come back. I want our water, our animals, our plants," she said as South Africa's government returned 40,000 hectares (100,000 acres) to her Khomani community in 1999. Her activism was matched by historians who say that the study of long-isolated languages will reveal the origins of human speech.

Remarkably, !Ui and a cousin language in Botswana, !Xoo, have proved more complex than almost any other. Spoken languages usually employ just 20 sound units or phonemes. English-speakers have 55 of them, but !Ui-speakers use more than 140, says Nigel Crawhall of South Africa's San Institute.

Study of such a complex language should reveal more about hunter-gatherer cultures. But time is short. When Mrs. Vaalbooi died last week, there was almost nobody left to say "!hoi ca", goodbye, in her mother tongue.

!Ui, !Xoo, !hoi ca