Teaching the Essential Principles of Development

A revolution in understanding developmental biology has been fueled by molecular and genetic approaches to the discipline. Two recently published textbooksofDevelopmental Biology are worthy contenders in the fight to maintain perspective in the midst of this molecular detail. Essentials of Developmental Biology by Jonathan Slack and Principles of Development by Lewis Wolpert, Rosa Beddington, Thomas Jessell, Peter Lawrence, Elliot Meyerowitz, and Jim Smith are intendedas introductions andoverviewsof the field suitable for undergraduate students. While both texts present the major principles and supporting evidence to the student, their approach to the material is very different. Slack focuses on the understanding of development gained throughmolecular and genetic experiments. In his streamlined presentation each sentence counts; theories and supporting experimental evidence are presented but interpretation is left largely to the student and instructor. This minimalist approach emphasizes the modern view over the classical. In contrast, Wolpert et al. present a more detailed narrative. Here too, the emphasis is on current molecular and genetic evidence, but such details are incorporated in the context of classical experiments. Wolpert et al. use the experimental evidence to promote and support their conceptual framework as a unified theory of development. The decision of which text to choose is based in part on teaching style. Instructors often use either a top-down or a bottom-up approach. In the top-down approach, the instructor uses a detailed text and winnows the essential material for the student. In a bottom-up approach, the instructor uses a sparse text as a foundation, then supplements with lectures, additional readings from the literature, popular press or other texts. Wolpert et al. approaches development from the topdown: they present concepts, theories and interpretations; experiments are used as support. Slack moves from the bottom-up: he presents the data that the teacher and student use to further their own synthesis.