Reviewed by: Austronesian Undressed: How and Why Languages Become Isolating ed. by David Gil and Antoinette Schapper Jiang WU David Gil and Antoinette Schapper (eds.) 2020. Austronesian Undressed: How and Why Languages Become Isolating (Typological Studies in Language 129). Amsterdam: John Benjamins Publishing Company. ix + 510 pp. isbn 978-90-272-0790-6 (HB), 978-90-272-6053-6 (E-Book). The book under review is an edited volume with the goal of addressing the question posed in its title: how and why Austronesian languages become isolating. More specifically, it concerns the Austronesian languages in an area which David Gil describes as a crescent, stretching from Hainan Island in the north, along coastal Mainland Southeast Asia into most of the Malay/ Indonesian archipelago, with the other tip of the crescent at the Bird's Head of New Guinea. The question posed by this book is of great interest and significance to both Austronesianists and a wider audience in fields such as historical linguistics, language contact, creolistics, and typology, for at least two reasons. For one, within the Austronesian family there is a tendency of simplification from Formosan and Philippine languages, which exhibit a considerably higher degree of morphosyntactic complexity, to those currently found in the so-called Isolating Crescent. Such a trend roughly correlates with the direction of the Austronesian dispersal, hence the study undertaken here is a probe into the history of Austronesian languages and their speakers as a whole. In addition, isolating languages appear to be the anomalies on a worldwide scale. The study of isolating Austronesian languages therefore relates to a broader inquiry into whether there is any common driving force behind the simplification processes of languages in general. This volume contains ten main chapters dealing with a wide range of Austronesian languages, including Cham, Riau Indonesian, Minangkabau, Javanese, Central Flores languages, Alorese and its close relative Lamaholot, Tetun Dili, and the languages of eastern Timor. Also included in the volume is an introduction which sets the scene for the book with a concise summary for each chapter, as well as a concluding chapter by John McWhorter (who introduced the metaphor of languages "undressing") with a critical review on much of the content. Chapter 1 by David Gil opens with the question of what it means to be an isolating language. Traditionally, the isolating nature of a language is associated with a low morpheme per word ratio, but it is notoriously difficult to properly define wordhood, upon which the notion of isolating rests crucially (Dixon and Aikhenvald 2002; Haspelmath 2011). Here, Gil defines word as a structural unit characterized by the convergence of a set of language-specific properties, and proposes a novel definition of isolating language as one that lacks a robust [End Page 791] structural unit of word. As Gil then demonstrates, a language like Riau Indonesian has few properties that can converge to define this unit of word, which means that Riau Indonesian has little morphological structure, and is therefore isolating. This chapter evokes some insightful thinking on morphological complexity and illuminates it with an elaborated and thorough case study. However, since the potential sources of evidence for wordhood are language specific, the question remains as to whether this view on morphological typology is readily applicable to other languages on a practical level, with crosslinguistically comparable results. Notably, while Gil intends to lay the groundwork for the remainder of the volume, his definition of isolating languages is not adopted in other chapters (except for an additional chapter on Riau Indonesian by Gil himself). The subsequent chapters present a range of rich and original data on how and to what extent the Austronesian languages in the Isolating Crescent display isolating structures, and many of them also emphasize the question of why. As is argued in most chapters, morphological loss and isolating traits can often be ascribed to language contact, but exactly what kind of contact scenario led to simplification remains a question that is subject to different interpretations. Much of the discussion in this volume centers around the debate between two views: a pre-Austronesian substratum or insufficient adult acquisition. I shall summarize and evaluate these two views in turn. Three chapters endorse the idea...