A solid base for scaling up: the structure of numeration systems

While numeration systems are found in almost every human society, they also vary strikingly around the globe. One important feature of many systems is being structured around a base. The presence, format and size of a base have implications for how representations of numbers are composed, conceptualized and used. The numerical cognition literature is rife with claims about which bases prevail, with sweeping generalizations on their origins and evolution. Yet these claims are rarely scrutinized, and research on numeration systems is plagued by a surprising lack of consensus on what a base <i>is</i>. This theme issue brings together scholars from the cognitive, social and behavioural sciences for a comprehensive overview of bases, aimed at creating common ground for communication and collaboration across disciplines. Contributions include (i) proposals for conceptual clarification and consistency, aided by a tool for visualizing system structure; (ii) reports on how bases are realized across different representational formats, cultures and time, in search of patterns and evolutionary trajectories; and (iii) analyses of cognitive implications and cultural imprints of bases. The main goal of this endeavour is to help build an integrative synthesis of both theorizing and findings on the cultural evolution of a key cognitive tool.This article is part of the theme issue 'A solid base for scaling up: the structure of numeration systems'.