EVOLUTION & DEVELOPMENT 3:5, 366–368 (2001) © BLACKWELL SCIENCE, INC. 366 BOOK REVIEW A review of Images of development: environmental causes in ontogeny by Cor van der Weele Brian K. Hall Department of Biology, Dalhousie University, Halifax NS Canada B3H 4J1 Correspondence (email: BKH@is.dal.ca) Images of Development. Environmental Causes in On- togeny. van der Weele, C. 1999. State University of New York Press, Albany. 182 pp. $19.95. ISBN 0-7914-4046-X. To demonstrate that the concept that embryonic development is neither predetermined nor preformed but controlled epigeneti- cally is over 100 years old, van der Weele discusses Hertwig’s (1894) epigenetic rebuttal to Weismann’s theory of determining factors controlling development. The term “epigenetics” was coined by C. H. Waddington (1956) as a preferred alternative to “Entwicklungsmechanik,” “experimental embryology,” or “de- velopmental mechanics.” Because the origin of the term is not well known, and because epigenetics is often misunderstood or used with different and nonoverlapping meanings, I include Waddington’s definition and rationale for that definition. The leader in this endeavor [study of the causal processes of devel- opment] was Wilhelm Roux, who coined the title “Entwicklungs- mechanik” for such studies. This word is still commonly employed in German. Its literal translation in English is “developmental me- chanics,” a phrase which is not only rather long and clumsy as the name of a branch of science, but which carries a perhaps unfortunate suggestion that only machine-like, physical processes are being en- visaged. Another rather awkward phrase, “experimental embryol- ogy,” is often used in English in its place. Perhaps the most satisfac- tory expression would be “epigenetics.” This is derived from the Greek word epigenesis, which Aristotle used for the theory that de- velopment is brought about through a series of causal interactions be- tween the various parts; it also reminds one that genetic factors are among the most important determinants of development. It is, how- ever, not yet in common use. (Waddington 1956, p. 10) Waddington used “epigenetics” to capture the essential com- bined genetic and environmental control of development; “Entwicklungsmechanik” implied much too mechanical a concept of development. In the intervening years, epigenet- ics has had three fates: • Epigenetics has been ignored by those reductionists who see genes controlling all aspects of intrinsic de- velopmental programs. • Epigenetics has been restricted to modification of gene activation through processes such as methylation, ge- nomic imprinting, and modification of chromatin structure, a view often referred to as “epigenetic inher- itance.” 1 • Epigenetics has survived to embrace all aspects of the control of gene activity in development (or for some, in ontogeny), whether that control is genetic or environ- mental, a view that we may call “epigenetic regulation of development” (Hall 1992, p. 89; van der Weele, p. 12). van der Weele’s book, a volume in the SUNY Series in Philosophy and Biology, is perhaps the most thorough eval- uation of and justification for the epigenetic regulation of de- velopment—the “environmental causes of ontogeny” of the subtitle. Although she builds on past definitions and analyses of epigenetics, van der Weele surpasses the attempts of many others (mine included) to keep epigenetic regulation of de- velopment before the biological community. Her blending of philosophical and biological approaches and treatment of the many classes of environmental control over development is both informed and informative. One very refreshing aspect is the way the biology informs the philosophy. So often, the philosophy can seem irrelevant to, obscure, or even obfus- cate the biology. 2 I learned as much if not more from this short book (139 pages of text, seven of notes, supported by 20 pages of references) than from almost any other treatment of the topics of epigenetics, phenotypic plasticity, cyclomor- phosis, and the environmental control of behavioral and structural evolution. van der Weele presents compelling ex- amples with which I was unfamiliar, which I had forgotten, or which I had not thought about in the context of the epige- netic regulation of ontogeny (the examples go beyond devel- 1 See Jablonka and Lamb (1995, 1998) for epigenetic inheritance, and see Hall (1998) and other papers in the same issue of J. Evol. Biol. for critiques of epigenetic inheritance. 2 For a recent argument for why the philosophy of science does matter, see Wilkins (2001).