The Family Tree

Bough, Drift, and Bridge worked the same great tree together — Bough among its branches, Drift listening to how it grew, Bridge walking the paths between its limbs — and together they could prove something that sounds impossible: that two languages, spoken oceans apart, are cousins. "Languages have families," said Bough, tracing a branch. "Sisters, cousins, ancestors. And we're not guessing — we can show it." "The trick," said Drift, "is that a language doesn't change all at once, or randomly." "And the proof," said Bridge, "is the words that still rhyme across the gap."

"Start with me," said Bough, high in the branches. "Related languages are genetically related — which just means they descend from a shared ancestor, one older language they all grew out of. We call that ancestor a proto-language. Usually no one alive ever heard it — it was spoken long before writing — so we reconstruct it, working backward from its living descendants, the way you might sketch a grandparent's face from a room full of grandchildren. Every language on one branch of my tree is a descendant of the same proto-language. None of them is the 'original.' They're all equally its children."

"Now the how," said Drift, who listened to the slow music of change. "Languages drift apart through regular sound change — and regular is the whole secret. When a sound shifts in a language, it doesn't change in one word and skip the next on a whim. It changes consistently — the same sound, in the same setting, shifts the same way across the entire vocabulary, over generations. One community's ancestors start softening a certain sound; their descendants soften it everywhere; meanwhile a sister community, far off, shifts a different sound its own consistent way. Give it centuries, and the two speech-communities can no longer understand each other — not from chaos, but from many small, regular changes piling up in different directions."