A New Scientist Best Popular Science Book of 2023 An Australian biologist delves into the extraordinary world of koalas, from their ancient ancestors to the current threats to their survival. Koalas regularly appeared in Australian biologist Danielle Clode’s backyard, but it was only when a bushfire threatened that she truly paid them attention. She soon realized how much she had to learn about these complex and mysterious animals. In vivid, descriptive prose, Clode embarks on a delightful and surprising journey through evolutionary biology, natural history, and ecology to understand where these enigmatic animals came from and what their future may hold. She begins her search with the fossils of ancient giant koalas, delving into why the modern koala has become the lone survivor of a once-diverse family of uniquely Australian marsupials. Koala investigates the remarkable physiology of these charismatic creatures. Born the size of tiny “jellybeans,” joeys face an uphill battle, from crawling into their mother’s pouch to being weaned onto a toxic diet of gum-tree leaves, the koalas’ single source of food. Clode explores the complex relationship and unexpected connections between this endearing species and humans. She explains how koalas are simultaneously threatened with extinction in some areas due to disease, climate change, and increasing wildfires, while overpopulating forests in other parts of the country. Deeply researched and filled with wonder, Koala is both a tender and inquisitive paean to a species unlike any other and a call to ensure its survival.