Numbers, words, and other symbols for precise quantities, are a human invention that had a broad impact on our cognitive and behavioral lives. This claim is based on extensive findings obtained by many researchers across a host of fields including linguistics, psychology, and archaeology. Through a novel synthesis of these findings, Numbers and the Making of Us shows that the invention and refinement of numbers across cultures had a profound impact on the human condition.A key point underscored in the experimental data surveyed is the following: While even at birth humans have some abilities to differentiate quantities, these abilities are very limited until we are taught number words and counting. We seem to have a native ability to discriminate small quantities from each other, say two from three items. We also have a native ability to discriminate large quantities from each other if they differ in marked ways. We can differentiate, for instance, four from twelve items even at birth.Surprisingly, perhaps, we require numbers to build upon these basic quantity differentiation skills. Numbers are the conceptual scaffolding that allows us to construct uniquely human quantitative thought. In the book, this point is supported with data from prenumeric children, anumeric adults in places like Amazonia, and members of other species.So how do humans arrive at numbers if we do not just “grow” into the recognition that, for instance, eight items can be consistently and precisely distinguished from nine items? How were numbers ever invented?Through the examination of linguistic data across cultures, the book highlights a simple point: Numbers are typically invented after people come to recognize correspondences between the fingers on their hands and other items in their natural environment.This manual route to numbers is not the only one cultures may take, but it is the most common route. As people come to recognize, in a haphazard and inconsistent manner, that a “hand” of something can refer to a specific quantity (five) of that something, they verbally reify numerical concepts. These verbal numbers can then be passed to others, refined, and built upon. The subsequent construction of more elaborate numerical concepts is essential to the development of other impactful cultural practices like agriculture and writing. In other words, the book suggests that the cognitive tools called numbers helped lead to a reshaping of the lives of most humans.