Introduction

Abstract This introductory chapter lays out the motivation and scope of Adaptationist Evo-Devo. It invites readers—students, evolutionary biologists, evo-devo practitioners, ecologists, physiologists, biology enthusiasts—to explore a framework that links developmental possibility and adaptive explanation. The aim is not to declare a theoretical revolution, but to offer something many in the have quietly wanted: a way to move forward that builds on the strengths of existing approaches. After years of calls to expand, rethink, or reimagine evolutionary biology, often for good reason, some biologists find themselves caught between camps, unsure where they stand. This book suggests that maybe they don’t have to choose. The book shows how population biology, comparative biology, developmental analysis, physiology, and modeling each contribute something essential, and that they work best in conversation. For students confused by evolutionary buzzwords and terminology, it offers a way in, framing evolutionary questions in terms of what development makes possible, and how selection acts on and shapes those possibilities. The label “adaptationist evo-devo” isn’t a provocation, but a practical shorthand for the kind of integrative reasoning many biologists already use. It also revisits long-standing conceptual divisions between those who view adaptation as a main explanation versus those who view developmental factors as a main explanation, not to flatten them, but to show how, in practice, the boundaries often dissolve. Development and selection are inextricable, and understanding form requires attending to both. The introduction closes with an invitation to approach the diversity of life with shared curiosity and a collaborative spirit.