Ecological Developmental Biology: Integrating Epigenetics, Medicine, and Evolution

Ecological Developmental Biology by Scott F. Gilbert and David Epel is a tremendous achievement of integration. The text discusses fields ranging from biogeography to chemical biology and diverse branches of the phylogenetic tree. It references both classic studies and the most recent primary data to illustrate the dependence of multi-cellular development on environmental context. The authors begin by establishing polyphenism, the ability of a single genotype to generate multiple phenotypes in response to environmental cues, as a common factor across plant and animal taxa. This concept is supported by well-known examples such as the temperature-dependence of sex determination in reptiles and by more exotic polyphenisms like stress-triggered cannibalism in spadefoot toad tadpoles. The authors include detailed molecular explanations for developmental phenomena and use recent epigenetic insights to explain how environment-induced phenotypes can be transmitted between generations. Also covered is the fascinating and surprisingly widespread phenomenon of developmental symbioses, wherein developmental cues are supplied by closely-associated foreign organisms. The second section discusses developmental disruptions caused by aberrant environmental signals and highlights the dramatic effects of teratogenic compounds and endocrine disruptors. Attention is drawn to the provocative hypothesis that disorders such as cancer and obesity have their roots in gene expression patterns established early in life. Although the focus shifts and the scope narrows, the theme of environmental sensitivity during development ties the book together. The final three chapters are likely to be the most controversial. Gilbert and Epel make an argument for the inclusion of organism-environment interaction alongside evolutionary developmental biology in an expanded evolutionary synthesis. In their opinion, evolutionary theory has erred in treating phenotypes as purely a consequence of genes and the environment as a passive selector between alternative phenotypes rather than a source of variation. They conclude with a preliminary attempt at integrating development, epigenetics, and the interaction between organism and environment into modern evolutionary theory. Their ideas are thoughtful and daring, if somewhat speculative. However, there can be no doubt that in this new and rapidly advancing field, detailed mechanisms will emerge to fill the gaps. One of the unusual features of Ecological Developmental Biology is the authors’ tendency to step outside the role of passive reporters and offer their own interpretations. The authors do not avoid the political implications of their ideas, especially where it concerns conservation biology and the effects of environmental contaminants on human health. In the philosophical “Coda,” which deserves a wider audience and perhaps its own book, they address how theories of development and evolution affect our understanding of human nature and the natural world and suggest that ecological developmental biology may modify the concept that evolution is a purely competitive affair. In an era in which research is advancing too fast for textbooks to keep up and the Internet is often a more convenient source of basic information, this book serves a unique role in providing the most recent information in a format that will encourage independent exploration of the primary literature and critical discussion of the authors’ ideas. This makes Ecological Developmental Biology more suited to an advanced seminar than a lecture-based course. Further, since Gilbert and Epel frequently indicate what is unknown and where more research is needed, this text also may be a starting point for scientists entering the field.