Evolutionary Theory is the published culmination of 30 years’ worth of collaboration between evolutionary biologists and philosophers of science. It provides a structure for framing our understanding of the relationship between evolution and all other aspects of biology. The book is divided into three parts, along with an introductory chapter and a concluding chapter. The introduction provides the history behind attempts to develop hierarchical thinking in developing evolutionary theory. Chapters in the first part address principles and basic organization of hierarchy as applied to biological evolution. The second part examines integration of hierarchical mechanisms within dynamic processes. The third integrates hierarchical theory and macroevolutionary patterns. The conclusion applies this structure to the extended synthesis debate.
First editor Niles Eldredge has been a key proponent of revolutionizing our understanding of the nature and pace of evolutionary processes. Eldredge, who is a past recipient of NABT's Distinguished Service Award, is emeritus curator of the Division of Paleontology at the American Museum of Natural History. Along with his coauthors and coeditors, he has assembled a diverse collection of chapters on how hierarchical thinking allows us to advance our understanding of the relationship between evolutionary mechanisms and all other aspects of biological history, processes, and dynamics.
Eldredge defines his use of the term “hierarchy” in the introduction: “that biological entities, be they molecules or species, are seen as parts of larger wholes—for example, populations are parts of species—and that this structural organization of biological entities is in itself germane to understanding the evolutionary process” (p. 1). Later in the introduction, he provides a figure that visualizes the correspondence between the ecological hierarchy (from biosphere, through lower levels such as biotic, population, organismal, and cellular) and the evolutionary (genealogical) hierarchy, from the top-level “tree of life” down through monophyletic taxa, populations, germlines, and genomes (Figure 0.2). Pievani returns to this central idea in the conclusion: “Organisms are simultaneously part of the two different interacting hierarchies: as reproducing ‘packages’ of genetic information (replicators), they are part of the genealogical hierarchy; as matter-energy transfer systems (interactors), they are part of the ecological hierarchy…” (p. 353).
The utility of hierarchical thinking in understanding biological history and processes is fully developed in the body of the book. For example, a chapter is devoted to explaining “why genomics needs multilevel evolutionary theory” (ch. 6). The struggle to understand and explain non-coding DNA, transposable elements, and the size of the genome is recast in light of the role of genes, individuals, and evolving populations as hierarchical levels that interact to produce the genome of an individual or a species. Hierarchical thinking has also prompted reinterpretation of the fossil record. Realizing that larger systems are composed of smaller ones, and that “process rates and products, integration, boundaries, spatiotemporal continuity, and other features can be different at different levels of organization” (p. 244) has shifted the way paleontologists view the forces at work and the magnitude of effect when exploring the causes of past events.
Evolutionary Theory is a framework for understanding the history of life on Earth and for coming to grips with ongoing biological processes and changes. It is being applied to “describe the multidimensional reduction of diversity in the biosphere during the Anthropocene, focusing on urbanization and urban scaling” (p. 362). The value of this way of thinking about evolution is fully explored and supported in this book, and further enhanced by the outreach of involved scientists organized as The Hierarchy Group (http://hierarchygroup.com/).
The organization of the book allows the reader to sample chapters in various ways; there is no need to begin at chapter one and read straight through. However, the introduction will provide a useful tool to comprehend the concepts and terminology used throughout. This volume is tightly packed with information; unless you already have a strong background in the field, you might find it challenging to comprehend the implications of the case being made. Re-reading earlier chapters might be more effective after reading the later chapters, as you gain more background. I think of this as a resource for my own “deep background” for understanding the mechanisms of evolution. Having read this, I find myself changing the phrasing I use when explaining evolution to my college freshmen. If you have an interest in evolutionary mechanisms, I recommend taking the time to dive in, repeatedly, to peruse chapters and revisit the introduction from time to time.
This compilation is technically excellent, but not an easy read; the depth and coverage probably are beyond the level needed for anyone other than a researcher.