Comparative Biomechanics: Life's Physical World. Steven Vogel. Princeton University Press, Princeton, NJ, 2003. 582 pp., illus. $60.00 (ISBN 0691112975 cloth).
A provocative article published in 1998 focused on a disparate group of scientists who pay for their own research (Jon Cohen, “Scientists Who Fund Themselves,” Science 279: 178–181). Their reasons for self-funding are dissatisfaction with the grant refereeing and awarding process, irritation over the time that grant applications can absorb, and the rejection of new ideas, which hampers innovation. I have met many of the scientists cited in this article and I find them admirable—exemplars who prompt my wistful reflection, “I wish I'd thought of that.”
Steven Vogel is one of those cited as using “his salary to fund his own relatively inexpensive research on biological fluid mechanics.” A professor at Duke University in Durham, North Carolina, Vogel has established an international reputation, starting with his doctoral work on the flight of fruit flies. His later work has probed such diverse topics as the design and ventilation of prairie dog burrows, leaves and sponges, the way in which the leaves of trees deform to resist high winds, and the design of plant stems. He is that rare animal, a biologist who is at once fluent in mathematics, conversant with physics and physical chemistry, and an accomplished practical engineer.
More than that, the quality of Vogel's writing allows him to convey complex ideas clearly and make them so accessible that his books are hard to put down. His Life in Moving Fluids: Physical Biology of Flow (Willard Grant Press, Boston, 1991) was the starting point for my studies in that area. His earlier Life's Devices: The Physical World of Animals and Plants (Princeton University Press, Princeton, NJ, 1988) was so attractive that I have “lost” two copies to my students; that book was deservedly awarded the Irving and Jean Stone Prize for Science Writing for Public Understanding. Steven Vogel is able, thanks to his skill with the pen, to bring his enthusiasm for functional studies of living organisms to a wide audience and thereby (and I write this with admiration) to supplement his salary substantially.
In the preface to his latest book, Vogel makes the point that while “biomechanics” is often taken to refer to human problems, particularly medical ones, the book's title, Comparative Biomechanics, embraces the whole natural world. The book is aimed at biology undergraduates at any level beyond introductory courses but, as is increasingly the case with modern biology, it presumes and often requires a passable knowledge of the physical sciences and mathematics.
The four introductory chapters deal with basic physical dimensions and their biological meaningful derivatives, such as power and work, force and pressure. Vogel introduces us to the Système internationale d'unités, to which he adheres sedulously throughout the book. He also starts us off on an accepted series of symbols for parameters: Here, accepted usage can be ambiguous; for example, “E” can stand for energy or Young's modulus of elasticity, while “e” stands for efficiency. Never fear: All the symbols he uses are listed on pages 519 and 520 and, where uncertainty could arise in the text, he is careful to guide us.
Part 2 comprises 10 chapters on fluids, starting with discussion of the static properties of gases and liquids and moving to flowing fluids, both around and within organisms. I particularly enjoyed chapters 12 and 13 on the generation of lift and thrust for swimming and flying. This is a rapidly moving and fertile field of biological research and Vogel handles it effortlessly and with great insight (fortunately, the book arrived just in time for me to update my first-year lectures). In my view, this section is a must for anyone studying animal locomotion.
The next 10 chapters deal with solids and structures. Vogel makes the useful points that most biological materials have a far greater range of properties than the materials of human engineering, and that organisms have the ability to alter material properties locally, modifying them in response to stress or the environment. He is careful to point out that organisms are not better engineers than humans and that, indeed, they often make the best of a limited palette of inorganic minerals and organic polymers, which often impose severe structural limitations; nonetheless, he clearly remains in awe of the amazing strength and energy-absorbing capacity of the silk of spiders.
Continuing from materials to structures and thence to mechanisms, he goes on to consider static structures, such as trees or shells, as well as moving structures, such as worms or horses. A key feature of the mechanics of animal movement is their use of muscle, which is the subject of one useful, accessible, and economical chapter. Muscle, Vogel points out, is tricky stuff: It can generate force, but it costs metabolic energy to do so even if it does no work; it can pull, but it cannot push; most curiously, it can be lengthened while activated and thereby absorb energy. In this chapter, Vogel skates around the details of muscle biochemistry and concentrates on its mechanics. This epitomizes the clarity with which he has focused his text.
In the concluding chapter, “Loose Ends and Perspectives,” Vogel moves away from his main themes to consider matters such as safety factors—how safe is adequate and in what contexts—and the ability of living organisms to respond mechanically to experience, something human engineering and material science is scratching at but with only limited success. He doesn't believe that nature does it better than we do, merely differently, and cites as evidence our dependence on wheels, chains, gears, and the other appurtenances of machinery, all of which are unknown in living organisms.
A litmus test of any book is the quality of its bibliography. In this book are 25 pages of references ranging in date from the middle of the 19th century to 2002 and, mirabile dictu, page citations for the references. Why doesn't everyone do this? There are occasional minor complications: D. E. Alexander is not distinguished in the text from the more prolific R. McN. Alexander, for example.
The standard of presentation and cross-referencing is, given the scale of the book, remarkably high. It is perhaps carping to wonder what the following sentence on page 382 means: “A banana leaf, pushed sideways, twists rather than bends, again using a structure, its petiole (or leaf stem), of very torsional stiffness.” Rather more serious is the discrepancy between the equation given for the second moment of area of an elliptical rod in figure 18.3 (p. 368) and that in the text on page 369 (the latter is correct).
One cannot leave this book without remarking on the easy gaiety with which Vogel sprinkles his writing with puns, literary asides, alliteration, and tactical use of one-word sentences. Space constraints allow me to give you only a few examples. On page 334, in the context of how a hole stops the propagation of a crack in a sheet of thin material, he writes, “This removal of further foil should foil the further facility of the foil to fail.” You get both pun and alliteration rolled into a single sentence. Again, in his attribution of the use of a polar plot that compares the lift and drag coefficients of airfoils, we find on page 251 that this was “a device introduced by that towering figure, Gustav Eiffel.”
Americans seem surprisingly loath to use hyphens, but Vogel does so to great effect: “Molecular techniques now make it unnecessary to seek out those near-oxymorons, functionless anatomical features” (p. 510). I could go on. This is one book I shall not lend to students; I will tell them they must buy it.
