Comparative Biomechanics: Life's Physical World (review)

Physiology is the study of how organisms work, and, in the minds of many biologists, it is a field concerned primarily with process. For example, texts on general comparative physiology are traditionally organized according to subjects such as circulation, respiration, or metabolism. But each of these processes relies on the mechanics of underlying structures. To understand the process of circulation, for instance, one must understand the mechanics of fluid flow and the properties of arterial walls. Indeed, it is possible to approach the study of how organisms work from a nontraditional perspective, one organized around the physics and engineering of living things. This is the thesis of Steven Vogel's monumental Comparative Biomechanics.

The biomechanical approach to physiology is not new—biomechanicists are fond of tracing their intellectual lineage back to the seminal work by Gallileo on the scaling of bones—and the field has grown rapidly in recent years. During this expansion, three texts have served as core tools for teaching biomechanics: Mechanical Design in Organisms (Wainwright et al. 1976), Animal Mechanics (Alexander 1983), and Life in Moving Fluids (Vogel 1994). Together, these texts provided a broad introduction to solid and fluid mechanics and their application to plants and animals, but teaching from them is problematic. Mechanical Design in Organisms is aimed at the practicing biomechanicist, and its compendious detail is likely to leave students gasping for air. Animal Mechanics admirably captures the spirit of the biomechanical approach, but the lack of intermediate steps in Alexander's mathematical treatment can be a frustration for undergraduates. Life in Moving Fluids is pitched right, but, as the name implies, it deals only with the mechanics of fluids. What practicing biomechanics has needed is a single, up-to-date, all-encompassing text that can serve as the basis for a unified course in the mechanical perspective on organismal function.

Hallelujah, our prayers have been answered! Comparative Biomechanics is just the text we have been waiting for. In this large but lively tome, Vogel provides an introduction to both the mechanics of fluids (air and water) and the mechanics of structural materials. These basic engineering principles are then applied to a wealth of biological topics, with a special emphasis on the mechanics of locomotion. Boundary-layer flows, life at low Reynolds numbers, flight, swimming, and the plumbing of circulatory systems are all introduced and tied together. The mechanics of simple and composite materials, beams, shells, and even muscle; it's all here.

As in Vogel's previous books, mathematics is kept to a minimum, and where employed, it is well explained.Vogel's knack for pithy analogies and puns keeps the reader amused and engaged (my personal favorite is reference to the jump of a flea as a "leveraged flyout"). Unusual in a text of this size, I found no errors worth mentioning. Vogel is clearly conversant with the whole field, and expert at cutting to the core of its principles. It will be easy to teach undergraduates from this text, and the breadth of material will allow instructors to pick and choose topics as appropriate.

Although primarily intended as an introductory level teaching tool, Comparative Biomechanics will nonetheless be useful to old hands in the field.There is little that is substantively new here (readers of Vogel's earlier books will recognize much that is familiar, including many of the jokes), but the synthesis of all of biomechanics is compelling, and Vogel has done a wonderful job of compiling references to recent work. The final chapter on the "Contexts of Biomechanics" serves well as a call for future work, and the excellent index makes it easy to find just the offbeat fact one is looking for.

As an introduction to a physical perspective on physiology, Comparative Biomechanics will serve as the standard of excellence for many years to come.