0 How the Cycladic Islanders Found Their Marbles: Material Engagement, Social Cognition and the Emergence of Keros Alexander Aston Received 7 Aug 2019; Accepted 25 Mar 2020; Revised 23 Mar 2020 This paper utilizes Material Engagement Theory (MET), which examines material culture as a dynamic and integral component of human cognitive systems, in order to explore the relationship between Cycladic marble sculpting and the complex social organization evinced at the sites of Dhaskalio and Kavos on the island of Keros. The article shows how the development of Cycladic sculpting in conjunction with transforming settlement patterns suggests that the figurines emerged as part of a kinshipping dynamic. In this context, evidence from the cognitive sciences reveals how Cycladic figurines were profound attention-capturing technologies which shaped the development of intersubjectivity and collective activity. Cycladic marble provided a medium through which a semiotics of value could be generated, circulated and manipulated across the archipelago. The article argues that marble artefacts formed part of a distributed cognitive system which enabled the regional organization of long-range voyaging regimes centred on Dhaskalio-Kavos. The role of Cycladic sculpture in mediating maritime social interactions is clarified by examining the dynamics of social cognition and the organizational burdens of long-range voyaging culture. The relationship between marble, social interaction and longboat voyaging provides a strong explanation for the development and transformation of Keros as well as for broader chronological developments in the region. Cycladic sculpting traditions mediated the shifting burdens upon social cognition during the Early Bronze Age, facilitating the novel forms of social organization in the central Cyclades as a response to both the pressures and the opportunities of the Aegean world. Keros provides an exemplary case study of material culture’s role in extending the boundaries of social cognition in ways that enable social complexity to emerge at new scales. Introduction The Early Bronze Age (EBA) was characterized by the rapid emergence of novel social complexity across Eurasia. In the Cycladic islands of the third millennium BC, new forms of social organization were intimately bound up with the development of sophisticated marble sculpting traditions. Cycladic figurines are one of the most celebrated and enigmatic classes of artefacts in all of archaeology (see Figure 1). The ‘canonical’ or ‘folded arm’ figurines of the Early Cycladic II (EC II, c. 2800–2300 BC) are stylized, iconic depictions of women that were created in the thousands and circulated throughout the Cyclades and beyond. Since the twentieth century, the perceived artistic value of the figurines has resulted in catastrophic looting, leaving the vast majority of known forms without any secure context (Marthari et al. 2017;