Mark Denny discusses Ecological Mechanics

According to Mark Denny, the time is right for biomechanics to be folded into the broader study of ecology. In Ecological Mechanics, Denny explains how the principles of physics and engineering can be used to understand the remarkable ways plants and animals interact with each other and their surroundings, and how this controls where species can survive and reproduce. Recently, Denny shared some thoughts on the emerging discipline and his new book:

Ecological MechanicsEcological mechanics is not something I’ve heard of. Is it a new field of study?

MD: Yes and no. Biomechanics, the field in which I was raised, has traditionally focused on trying to understand how individual plants and animals work: how they are shaped to perform certain functions, what materials they are constructed from, how they interact with wind and moving water. But this biomechanical perspective has matured to the point where it can now be productively applied to questions of how individuals interact. In other words, the time is right for biomechanics to be folded into the broader study of ecology. That’s the basic idea of the book: to reveal to ecologists can they benefit from incorporating some physics and engineering in their approach, to challenge biomechanics to extend their expertise beyond the individual, to bring two well established disciplines together.

Can you give me a good example of ecological mechanics in action?

MD: I’d be delighted to! Let’s take coral reefs. They are an iconic example of how an assemblage of plants and animals interact to build a community that can grow and persist in a physically stressful environment, in this case the wave-beaten shores of tropical islands. But coral reefs exist in a delicate balance. Fish that shelter among branching coral colonies eat the seaweeds that otherwise would outcompete corals for space on the reef. If too many of the branching corals are broken by waves, the fish population declines, and the seaweeds take over. So, the state of the reef is a complex interaction between fluid mechanics (which governs wave forces), solid mechanics (which governs the ability of corals to resist those forces), and ecology, (which accounts for the community-wide consequences of coral breakage). But ecologists have had no way to predict how these interactions will play out as climate changes. Fortunately, ecological mechanics can now provide the answer. By taking into account both the predicted increase in intensity of tropical cyclones and the reduction in strength of corals due to ocean acidification, we can use the principles of engineering to accurately predict the change in species composition on a reef, and, from that, to use ecological principles to predict the change in competitive interactions between corals and seaweeds.

What’s the scope of the subject matter?

MD: Broad! In the first section we cover basic concepts from the physics of diffusion to fluid mechanics. We then use those concepts to understand the forces that plants and animals encounter both on land and in water, how animals move, and how the environment affects the temperature of everything, both living and dead. Then there’s a section on the mechanics of materials: how the chemical composition of a structure determines its stiffness and strength, how the shape of the structure affects the forces imposed on materials, and how structures interact in dynamic fashion with their surrounds. We then finish up by tying together the information from the previous sections. We explore how variation in the environment affects the plants’ and animals’ performance, and how that variation changes through time and space. We delve into the statistics of extremes (which can be used to predict the likelihood of ecological catastrophes), and we see how physics causes ecological patterns to emerge even in physically uniform habitats. There’s plenty here for both terrestrial and aquatic biologists, at scales ranging from the molecular to the global.

What tools will I take away from reading Ecological Mechanics?

MD: Great question. In a nut shell, you should come away with enough practical knowledge not only to understand the ecomechanics literature, but also to start working as a practicing ecomechanic. The chapter on thermal mechanics, for instance, teaches you how to construct a head-budget model for an organism that you can use to predict body temperature in any environment. The chapter on scale transition theory provides a recipe for predicting how the average performance of a population will change as the population spreads through space.

Sounds pretty technical, though. How much of a background in physics, math, and engineering would one need?

MD: Not much, actually. If you’ve had a course in basic physics somewhere along the line, and remember a reasonable amount of the algebra you learned in high school, the ideas presented here are should be easy to absorb. My own formal background in math and physics is absolutely minimal. Most of what I know about engineering I learned by explaining it to myself, and I think that has put me in a good position to explain this material to others. Readers are likely to be pleasantly surprised at how far a little bit of mathematics and basic physics can take them.

Given the scope and level of the discussion, what do you see as the audience for Ecological Mechanics?

MD: I wrote this text with several audiences in mind. First, there are ecologists and biomechanics actively involved in research, everyone from undergraduates on up. I feel certain that the breadth of information presented here will provide them with new perspectives on their subjects, new ways of thinking about the ways in which plants and animals interact with each other and with their environment, and the tools to explore those thoughts. The text can also be used as the basis for an upper-level undergraduate course. Combining as it does biomechanics and ecology, it could easily fit into a general curriculum in biology. It could equally well provide accessory information for other courses; various chapters could be used in isolation in a general biomechanics course, for instance, or a general course in ecology. And lastly, I hope there is an audience among folks who are just interested in science. Ecological mechanics involves such a compelling mixture of physical and biological science; I’m hoping that people will pick up this book just to scratch the itch of curiosity.

How did someone with little background in math and physics end up in a field like ecological mechanics?

MD: Pure serendipity. Like so many people, I went to college planning to go to medical school. I majored in zoology, avoided math, and put off taking physics until my senior year, and even then I took it pass/fail. But I found that physics offered a different (and intriguing) way of thinking about the world. And that really clicked into place when, in my final semester, I took a biomechanics course from Steve Wainwright and Steve Vogel. They showed me how the physics perspective could be applied to biology, and I’ve been riding that wow!! feeling ever since. I’d love to pass that excitement along to others, and books like this are best way I know to do that.

Mark Denny is the John B. and Jean DeNault Professor of Marine Sciences at Stanford University’s Hopkins Marine Station in Pacific Grove, California. His books include Biology and the Mechanics of the Wave-Swept Environment, Air and Water, and How the Ocean Works.

Running Randomized Evaluations

Glennerster_RunningRandomized “The popularity of randomized evaluations among researchers and policymakers is growing and holds great promise for a world where decision making will be based increasingly on rigorous evidence and creative thinking. However, conducting a randomized evaluation can be daunting. There are many steps, and decisions made early on can have unforeseen implications for the life of the project. This book, based on more than a decade of personal experience by a foremost practitioner and a wealth of knowledge gathered over the years by researchers at J-PAL, provides both comfort and guidance to anyone seeking to engage in this process.”–Esther Duflo, codirector of J-PAL and coauthor of Poor Economics

Running Randomized Evaluations: A Practical Guide
Rachel Glennerster & Kudzai Takavarasha

This book provides a comprehensive yet accessible guide to running randomized impact evaluations of social programs. Drawing on the experience of researchers at the Abdul Latif Jameel Poverty Action Lab, which has run hundreds of such evaluations in dozens of countries throughout the world, it offers practical insights on how to use this powerful technique, especially in resource-poor environments.

This step-by-step guide explains why and when randomized evaluations are useful, in what situations they should be used, and how to prioritize different evaluation opportunities. It shows how to design and analyze studies that answer important questions while respecting the constraints of those working on and benefiting from the program being evaluated. The book gives concrete tips on issues such as improving the quality of a study despite tight budget constraints, and demonstrates how the results of randomized impact evaluations can inform policy.

Suggested courses:

  • Program evaluation courses taught in Master in Public Administration/ International Development, Master of Business Administration, and Master of Public Administration programs.
  • Masters of Public Policy courses focusing on economics and impact evaluation.


Table of Contents

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Peter Dougherty reflects on the latest crop of textbooks from Princeton University Press

Dear Readers,

As summer moves (perhaps too swiftly) from July to August, and soon enough to September, we are celebrating our new array of excellent advanced textbooks, titles crucial to research and teaching in the academy. A scholar once characterized an outstanding text as a book that brings “point, verve, and a sense of general acceptance” to the field which it defines—a worthy objective, among others, of a scholarly publisher such as Princeton University Press.  (Please don’t ask me to identify the source; I came across this quote about 30 years ago).

Textbooks of a scholarly stripe have long held a proud place on Princeton’s list, dating back many decades, and have complemented our monographs and more general interest titles in serving up robust accounts of the fields in which we publish.  This year is no exception, featuring as it does the impressive cluster of advanced texts we’ve published since last fall.  In fact, this is arguably the best set of new texts we have published in years.  And this bumper crop of texts is unusual in that spans most of the fields in which we publish, not just one or two.  As we approach some of the big annual academic meetings, and with fall semester only a month away, it’s worth our reviewing some of these outstanding offerings.

Most notable in this year’s crop are the new science texts.  The earliest of our new science texts appeared last August in the form of Wally Broecker and Charles Langmuir’s new edition of the classic work, How to Build a Habitable Planet.  Habitable Planet was quickly followed by Biophysics: Searching for Principles by William Bialek, and an innovative new book on the physics of sound and music, Why You Hear What You Hear by Harvard’s Eric Heller.  Our science offerings concluded this past spring with Einstein Gravity in a Nutshell by Anthony Zee, author of the modern classic Quantum Field Theory in a Nutshell, now in its second edition, and Climate Dynamics, an exciting new book by Texas-based scholar Kerry Cook.  Rounding out the spring flock of science texts are the second edition of Steven Vogel’s Comparative Biomechanics, and Whitney Cranshaw and Richard Redak’s exciting Bugs Rule! An Introduction to the World of Insects.  Collectively, these texts are helping to turn a new page in PUP’s science publishing.

While launching the new science texts, we added handsomely to our world-leading list of economics texts with new offerings by two of our most successful and celebrated textbook authors: Stanford’s David Kreps, whose 1990 book, A Course in Microeconomic Theory, marked the rise of the modern PUP economics list, is back with his new text, Microeconomic Foundations I: Choice and Competitive Markets, while MIT’s Robert Gibbons, author of the widely admired 1992 book, Game Theory for Applied Economists, joined Stanford’s John Roberts in editing the path-breaking Handbook of Organizational Economics. In addition, we published Berkeley economist Steven Tadelis’s long-awaited Game Theory: An Introduction, and an important edited volume by Princeton psychologist Eldar Shafir, Behavioral Foundations of Public Policy.  Shafir’s volume touched a nerve at The New York Times when columnist David Brooks used it as the basis for a January 2013 column. These books and more will be on display later this month at the European economics meetings in Sweden.

The list of 2012-13 textbooks extends from science and economics into various other regions of the social sciences.  We began the academic year with Phillip Bonacich and Philip Liu’s Introduction to Mathematical Sociology, and finished the year on an equally quantitative note with Moore and Siegel’s new book, A Mathematical Course for Political and Social Research, two titles we will feature prominently at this month’s meetings of the American Political Science Association and the American Sociological Association. In anthropology we added two new teaching titles in Ethnography and Virtual Worlds by Tom Boellstorff and his colleagues, and Nikolas Rose and Joelle Abi-Rachid’s Neuro: The New Brain Sciences and the Management of the Mind.

Returning to the earliest months of the past academic year, it’s worth recalling that we published the fourth edition of the famed Princeton Encyclopedia of Poetry and Poetics in a low-priced paperback edition, thereby making it course adoption-ready in seminars on poetics and advanced classes on poetry.

For more on these and other textbooks, please check out Princeton Pretexts where we will be posting additional information about these titles over the coming weeks or our dedicated textbooks web site.


Peter Dougherty
Director of Princeton University Press

Einstein Gravity in a Nutshell

Zee_EinsteinGravityNutshell Einstein Gravity in a Nutshell is a remarkably complete and thorough textbook on general relativity, written in a refreshing and engaging style. Zee leads us through all the major intellectual steps that make what is surely one of the most profound and beautiful theories of all time. The book is enjoyable and informative in equal measure. Quite an achievement.”–Pedro Ferreira, University of Oxford

Einstein Gravity in a Nutshell
A. Zee

  • Provides an accessible introduction to Einstein’s general theory of relativity
  • Guides readers from Newtonian mechanics to the frontiers of modern research
  • Emphasizes symmetry and the Einstein-Hilbert action
  • Covers topics not found in standard textbooks on Einstein gravity
  • Includes interesting historical asides
  • Features numerous exercises and detailed appendices
  • Ideal for students, physicists, and scientifically minded lay readers
  • Solutions manual (available only to teachers)


Table of Contents

Sample this textbook: Introduction [PDF]

Additional information about the In the Nutshell series

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