Numbers do not exist in all cultures. There are numberless hunter-gatherers embedded deep in Amazonia, living along branches of the world’s largest river tree. Instead of using words for precise quantities, these people rely exclusively on terms analogous to “a few” or “some”.

In contrast, our own lives are governed by numbers. As you read this, you are likely aware of what time it is, how old you are, your checking account balance, your weight and so on. The exact (and exacting) numbers we think with impact everything from our schedules to our self-esteem.

But, in a historical sense, numerically fixated people like us are the unusual ones. For the bulk of our species’ approximately 200,000-year lifespan, we had no means of precisely representing quantities. What’s more, the 7,000 or so languages that exist today vary dramatically in how they utilise numbers.

Cultures without numbers, or with only one or two precise numbers, include the Munduruku and Pirahã in Amazonia. Researchers have also studied some adults in Nicaragua who were never taught number words.

Without numbers, healthy human adults struggle to precisely differentiate and recall quantities as low as four. In one experiment, a researcher will place nuts into a can one at a time, then remove them one by one. The person watching is asked to signal when all the nuts have been removed.

Responses suggest that anumeric people have some trouble keeping track of how many nuts remain in the can, even if there are only four or five in total.

This and many other experiments have converged upon a simple conclusion: when people do not have number words, they struggle to make quantitative distinctions that probably seem natural to someone like you or me. While only a small portion of the world’s languages are anumeric or nearly anumeric, they demonstrate that number words are not a human universal.

It is worth stressing that these anumeric people are cognitively normal, well-adapted to the environs they have dominated for centuries. As the child of missionaries, I spent some of my youth living with anumeric indigenous people, the aforementioned Pirahã who live along the sinuous banks of the black Maici river.