Ewald R. Weibel
Symmorphosis: On Form and Function in Shaping Life

"In engineering, it is important to design a machine for the most economical functioning, and to build it as cheaply as possible. The underlying principle is to be economical with resources both in the construction process and in the operation of the machine. Is it also a principle in biology to build organisms economically, not to waste resources and to achieve the least expensive operation?" (p. 12)
In this highly technical, initial book length treatment of the subject of symmorphosis Weibel attempts to show that animals are "designed" economically. He also paves the way for further research on the subject with ideas about how to do so.

Outside of the first and last chapters, readers are feed little besides the details of quantitative studies performed on cells, tissues, muscles, organs (especially the lungs), and blood vessels. Few will want to get into the details of the middle chapters. They can be quite dense. They also seem to function as a sort of smoke screen to the problems of the theory. How can something not be correct when we have so many numbers to support it? Right? Wrong. At least sometimes wrong.

Not to suggest that symmorphosis is dead in the water or doesn't have much truth to it, but as defined in the Preface, symmorphosis simply isn't going to always be the case. It will never be a scientific theory with universal application. That definition is

that the quantity of structure incorporated into an animal's functional system is matched to what is needed: enough but not too much. (p. xii)
In our world of natural selection this seems to make sense--at least on the surface. If a functional system doesn't have "enough" of something then natural selection will drive the species to the point of having enough. However, natural selection isn't perfect and genetic drift happens. Natural selection can be slow. It can be behind the times and the current environment. And it can only work with what it is initially given or with what it has already developed. These factors alone should be enough for the pioneers in the field to change the definition of symmorphosis to something a little more flexible and much less exact. However, it isn't until some very short disclaimers near the end of the book that Weibel admits the possibility of exceptions and pitfalls of his theory.

Early on Weibel claims that "cells are designed economically" and that it is an established "principle that cells do not burden themselves with baggage they don't need." (p. 14) While this is partially true, it does still ignore the fact that there is "too much" of some things at the cellular level thanks to the cumulative nature of evolution. For instance, most DNA is "junk", otherwise known as pseudogenes, and can hardly be called or considered economical. On the macro scale, vestigial organs and other body parts are completely ignored. Evolution tends to get around to removing or converting such things, but it takes numerous generations to weed out these inefficiencies. Symmorphosis should include, rather than turn a blind eye to, items like these and incorporate them into a working, flexible framework.

Another possible methodological error committed is the apparent attribution of everything an animal is to its genes. For instance, the section between and including pages 47-50 doesn't determine whether the differences in mitochondria per muscle is caused mostly by genes or the environment (including exercising). Fast running animals (including only some athletic humans) have higher mitochondria counts. So what? Are they "designed" that way via evolution or did they get that way by running fast and often? We don't know whether the people were born athletes or whether they became such through training. Without answering this question the design element of symmorphosis theory seems to go out the window. The experiment would be a simple one (albeit unnatural and perhaps unethical and cruel). Raise one of the pronghorn (shown on the book cover and used in many of the examples) in captivity and don't allow it to exercise. Then compare its mitochondria count with the domesticated goats (which is the other animal it is compared to in the book) and the mitochondria counts of wild pronghorn who are running on a daily basis.

At the conclusion of an experiment (involving O2 pathways), the results "find that no excess structure is maintained." (p. 208) That may, or may not, be true for the case at hand, but it certainly doesn't have universal application. George Williams wrote a book that focuses almost entirely on the waste that we can easily find in organisms. Others have found waste and excess structure in the neuroanatomy. The list could go on and on.

Finally, on page 212, Weibel begins to move to firmer ground. He states

What counts is not perfection in the design of each element in the sense of the engineer, but rather the tendency to achieve a well-balanced optimum for the whole on the basis of what is available in the first place... What counts in an integrated system such as an animal body is good integration of the parts to make a successful whole, and this is where symmorphosis appears as a most useful theory worth pursuing and testing.
This last sentence is finally right on the mark, but it isn't what most of the book is about. Most of the book attempts to "prove" animal parts and wholes are optimally designed, that things are perfect, and that there is no waste. A more objective and readable approach could have been taken. Weibel frankly admits this near the end on page 217.
I could have...[looked] around for anecdotal evidence, good examples where form and function are closely connected--and there are many--as well as cases where the principle seemingly fails.
This is what I would have liked to have seen, but Weibel feels that would have led to disconnected examples. I disagree. Big picture thinking that doesn't ignore the areas where Weibel's version of the principle fails ultimately will lead to a better theory, more research, and more findings.

from the publisher:
This book addresses a simple question: Are animals designed economically? The pronghorn can run at speeds of up to 60 kilometers an hour and can maintain this speed for nearly a full hour. Clearly, the form of this elegant animal is beautifully matched to the function it needs to perform.

This is symmorphosis. The theory of symmorphosis predicts that the size of the parts in a system must be matched to the overall functional demand. Moreover, it predicts that animals must provide their complex systems with a functional capacity that can cope with the highest expected functional demands, possibly including some safety margin to prevent the system from failing when it is overloaded. In Symmorphosis, Ewald Weibel tests these predictions by working out the quantitative relations between form and function.

Physiologists will value this book because Weibel shows them that morphological information can be as quantitative as physiological data. Anatomists will value the book for its demonstration that advanced integrative physiology crucially depends on adequate but rigorously quantitative and testable information on structural design. Finally, anyone interested in the origins of the diverse forms of animals will be fascinated by Weibel's demonstrations that show how animals as different as shrews, pronghorns, dogs, goats--even humans--all develop from essentially the same blueprint by variation of design. This is a hidden beauty of the animal kingdom, which can be uncovered by a rigorous investigation of the quantitative relations of form and function.

Ewald R. Weibel is Professor of Anatomy, Emeritus, University of Berne.

"Symmorphosis is (and I use the term advisedly) magisterial: the best description anywhere of a provocative and creatively stimulating research approach to a large number of very important basic questions in animal--more specifically mammalian and human--anatomy, physiology, and evolution. This book is synthetic in the best sense of that word."
--Malcolm S. Gordon, University of California, Los Angeles