Life without numbers in a unique Amazon tribe
The Pirahã of the Amazon have almost legendary status in language research. They have no words at all for number. They use only only three words to count: one, two, many.

To make things confusing, the words for one and two, in Pirahã, are the same syllable, pronounced with a falling or rising inflection. And to make things really difficult, the word for one can sometimes mean “roughly one”, and the word for two can sometimes mean “not many”.

They provided a test for an old riddle: do words determine thought or does thought determine words?

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Peter Gordon, the psychologist at Columbia University in New York City who carried out the experiment says, “This is the first convincing evidence that a language lacking words for certain concepts could actually prevent speakers of the language from understanding those concepts.”

In order to test if their language prevented members of the tribe from perceiving higher numbers, Gordon set seven Pirahã a variety of tasks. In the simplest, he sat opposite an individual and laid out a random number of familiar objects, including batteries, sticks and nuts, in a row. The Pirahã were supposed to respond by laying out the same number of objects from their own pile. For one, two and three objects, members of the tribe consistently matched Gordon’s pile correctly. But for four and five and up to ten, they could only match it approximately, deviating more from the correct number as the row got longer.

The Pirahã also failed to remember whether a box they had been shown seconds ago had four or five fish drawn on the top. When Gordon’s colleagues tapped on the floor three times, the Pirahã were able to imitate this precisely, but failed to mimic strings of four of five taps.