BEYOND the town of Cordova, on Prince William Sound in south-eastern Alaska, the Copper River delta branches out in silt and swamp into the gulf. Marie Smith, growing up there, knew there was a particular word in Eyak, her language, for the silky, gummy mud that squished between her toes. It was c'a. The driftwood she found on the shore, 'u'l, acquired a different name if it had a proper shape and was not a broken, tangled mass. If she got lost among the flat, winding creeks her panicky thoughts were not of north, south, east or west, but of “upriver”, “downstream”, and the tribes, Eskimo and Tlingit, who lived on either side. And if they asked her name it was not Marie but Udachkuqax*a'a'ch, “a sound that calls people from afar”.

Upriver out of town stretched the taiga, rising steadily to the Chugach mountains and covered with black spruce. The spruce was an Eyak dictionary in itself, from lis, the neat, conical tree, to Ge.c, its wiry root, useful for baskets; from Gahdg, its blue-green, flattened needles, which could be brewed up for beer or tea, to sihx, its resin, from which came pitch to make canoes watertight. The Eyak were fishermen who, thousands of years before, were thought to have crossed the Bering Strait in their boats. Marie's father still fished for a living, as did most of the men in Cordova. Where the neighbouring Athapaskan tribes, who had crossed the strait on snowshoes, had dozens of terms for the condition of ice and snow, Eyak vocabulary was rich with particular words for black abalone, red abalone, ribbon weed and tubular kelp, drag nets and dipping nets and different sizes of rope. One word, demexch, meant a soft and treacherous spot in the ice over a body of water: a bad place to walk on, but possibly a good one to squat beside with a fishing line or a spear.

This universe of words and observations was already fading when Marie was young. In 1933 there were 38 Eyak-speakers left, and white people with their grim faces and intrusive microphones, as they always appeared to her, were already coming to sweep up the remnants of the language. At home her mother donned a kushsl, or apron, to make cakes in an 'isxah, or round mixing bowl; but at school “barbarous” Eyak was forbidden. It went unheard, too, in the salmon factory where Marie worked after fourth grade, canning in industrial quantities the noble fish her people had hunted with respect, naming not only every part of it but the separate stems and shoots of the red salmonberries they ate with the dried roe.

As the spoken language died, so did the stories of tricky Creator-Raven and the magical loon, of giant animals and tiny homunculi with fish-spears no bigger than a matchstick. People forgot why “hat” was the same word as “hammer”, or why the word for a leaf, kultahl, was also the word for a feather, as though deciduous trees and birds shared one organic life. They lost the sense that lumped apples, beads and pills together as round, foreign, possibly deceiving things. They neglected the taboo that kept fish and animals separate, and would not let fish-skin and animal hide be sewn in the same coat; and they could not remember exactly why they built little wooden huts over gravestones, as if to give more comfortable shelter to the dead.

The end of the world

Mrs Smith herself seemed cavalier about the language for a time. She married a white Oregonian, William Smith, and brought up nine children, telling them odd Eyak words but finding they were not interested. Eyak became a language for talking to herself, or to God. Only when her last surviving older sister died, in the 1990s, did she realise that she was the last of the line. From that moment she became an activist, a tiny figure with a determined jaw and a colourful beaded hat, campaigning to stop clear-cutting in the forest (where Eyak split-log lodges decayed among the blueberries) and to get Eyak bones decently buried. She was the chief of her nation, as well as its only full-blooded member.

She drank too much, but gave it up; she smoked too much, coughing her way through interviews in a room full of statuettes of the Pillsbury Doughboy, in which she said her spirit would live when she was dead. Most outsiders were told to buzz off. But one scholar, Michael Krauss of the University of Alaska at Fairbanks, showed such love for Eyak, painstakingly recording its every suffix and prefix and glottal stop and nasalisation, that she worked happily with him to compile a grammar and a dictionary; and Elizabeth Kolbert of the New Yorker was allowed to talk when she brought fresh halibut as a tribute. Without those two visitors, almost nothing would have been known of her.

As a child she had longed to be a pilot, flying boat-planes between the islands of the Sound. An impossible dream, she was told, because she was a girl. As an old woman, she said she believed that Eyak might be resurrected in future. Just as impossible, scoffed the experts: in an age where perhaps half the planet's languages will disappear over the next century, killed by urban migration or the internet or the triumphal march of English, Eyak has no chance. For Mrs Smith, however, the death of Eyak meant the not-to-be-imagined disappearance of the world.