An Amazonian Language With No Word for Two

On the Maici River in the Brazilian Amazon, the roughly 800 Pirahã speak a language that, by most counts, has no exact number words at all. Daniel Everett — who lived among the Pirahã for years as a missionary, learned the language well enough to translate, and lost his faith somewhere along the way — argued that what looks like "one," "two," and "many" are better translated as "a small amount," "a somewhat larger amount," and "a lot." The boundaries shift with context. There is no morphological singular-plural distinction either.

In 2008, a team led by MIT psycholinguist Edward Gibson and Michael Frank ran controlled matching tasks with Pirahã adults: line up the same number of objects across from a model line. With one to three items the speakers were near-perfect. From four upward, accuracy collapsed in a graceful curve, especially when memory was involved (the model line briefly hidden). The Pirahã were not failing at perception. They were failing at the cognitive trick of holding a precise cardinality in mind without a word to peg it to.

Gibson and Frank's finding was a careful one. It is not that the Pirahã cannot think numerically; it is that exact numerical thought above the subitizing range turns out to be something language scaffolds rather than something it simply names. Number words are, in their phrase, a cognitive technology — a tool that the rest of us inherit so early we mistake it for an instinct.

The Pirahã case did not settle every question it raised. It just raised them in a way nobody has been able to ignore.