American Scientist

This Is Biology: The Science of the Living World. Ernst Mayr. 327 pp. The Belknap Press of Harvard University Press, 1997. $29.95.

Without question, the 20th century has been the epoch of biology—as measured by its advances, its total research support including that for practical areas such as medicine and agriculture, and its growing importance to our future. One only has to consider the serious problems posed by population growth, the deterioration of the environment and the increase in infectious diseases to realize the prime importance biology will have to the continued existence, not to say anything about the success, of the human species. No other science has been more relevant for humans during the past 100 years or will be for the foreseeable future. Hence a thorough understanding of biology is essential for all who want to consider themselves educated and responsible. But such knowledge is not easy to obtain, even for professional biologists, because of the breadth of research disciplines and the diversity of explanatory systems within biology.

This Is Biology, from the leading evolutionary biologist of this century, presents a view and understanding of biology that serves the specialist in biology, the general scientist and the layperson alike. The vast majority of biological research is in functional biology, as are most treatments about the life sciences for the general reader. What Mayr believes is needed and what he advances so forcefully in this volume is an examination of biology from the position of evolutionary explanations.

The author presents a broad scope of biology covering more than two centuries, demonstrating an encyclopedic grasp of empirical facts and theoretical concepts of the life sciences. This Is Biology is a project that very few biologists would even consider undertaking and even fewer could complete successfully. It is written in reasonably nontechnical and clear, yet forceful language that is supported by a detailed glossary, an index and literature citations. The ideas and information in each section are introduced in a historical presentation, which not only gives the reader a clear picture of the development of biological concepts and facts, but also is the best method to present the intricacies of biological details to either the nonspecialist or the biological specialist.

Mayr's analysis of biology is founded on three major points. First and foremost, he considers biology from an evolutionary point of view that is not only his great strength, but is also most critical for a general volume on biology at this time. Second, he argues for the strict autonomy of biology under the heading of organicism, in that there are biological explanations that cannot be reduced to laws or explanations in the physical sciences. Third, Mayr examines reductionism of all types as it is applied to the biological sciences and contrasts it with a holistic approach, favoring the latter.

Organicism is central to the entire exploration of biology in this volume, and this discussion must be read with considerable care and thought; Mayr's discussion of organicism is terse and difficult, but his concept represents a major and new approach to biology. The term organicism may not be the best for Mayr's paradigm, however, because the word was introduced by Ritter, and was used to express much the same idea as the holism advocated by Smuts and others. The difference between the earlier concept of organicism and Mayr's more elaborate one was not clear to me until I had given the material several close readings. Mayr's organicism actually includes organization, but more importantly it also encompasses the genetic program, evolutionary explanations and even certain functional explanations—a very broad view of what is unique to biology.

Mayr defines organicism in the glossary as "the belief that the unique characteristics of living organisms are not due to their composition but rather to their organization." This definition covers much of Mayr's ideas—but not all, because it omits mention of the genetic program and of evolutionary explanations. Perhaps the definition could be sufficiently broadened by adding "and evolutionary history" at the end. The definition of organicism with the addendum mentioned above provides a clear idea of this important new paradigm; yet considerably more analysis will be required—far more than could be presented in this small volume—before all details of this simple definition are appreciated. Clearly organicism also includes a number, but not all or even most, functional explanations in biology. Clarification of just which functional explanations are included in organicism will constitute a major problem in detailing the context and limits of this new paradigm. There is much fascinating work ahead for interested biologists and philosophers.

The author stresses the distinction between proximal versus ultimate causation, or functional versus evolutionary explanations, and their different roles in biological analyses. Unfortunately, functional versus evolutionary explanations are not synonymous with nomological-deductive and historical-narrative explanations as has been assumed by most workers. All functional explanations appear to be nomological-deductive, and all historical-narrative explanations appear to be evolutionary, but there is a sizable part of evolutionary explanations that is strictly the former. The overlap between these systems of explanations in biology continues to confuse much biological inquiry.

Unfortunately, the book's discussion of functional biology—a major part of biological activity—is largely lacking. This is the result partly of Mayr's desire to cover what he considers to be the core of biology, namely that part of the biological sciences falling under the heading of organicism, and partly of considerations about the structure and length of this work. Functional biology is restricted mainly to the eighth chapter, "'How?' Questions: The Making of a New Individual," but even this chapter deals largely with evolutionary matters. Other material on functional explanations originally included in the manuscript was omitted at the last minute.

Clearly no explanation in biology is complete in the absence of an evolutionary explanation that holds for all levels of biological organization including the molecular and cellular. Yet functional explanations are essential prerequisites for any evolutionary explanation, a fact that has been ignored by most evolutionary biologists. Moreover, the statement Mayr quotes from Theodosius Dobzhansky, "Nothing in biology makes sense except in the light of evolution," is simply not true. Functional explanations in biology, even in the complete absence of any evolutionary consideration, make a great deal of sense, as is apparent every time you get a diagnosis from your doctor about what ails you. These diagnoses may not be complete biological explanations, but they do make sense and are of much concern to you, the patient!

Although much functional biological explanation on all levels of organization can be reduced completely to physics and chemistry, it is clear that not all functional explanations can be so reduced. A major challenge in biology is to ascertain those functional explanations that cannot be reduced to the laws of the physical sciences. Some possibilities include the Hardy-Weinberg law of equilibrium, and all the population genetics based on it, and the concept of ecological competition. The lack of a fuller discussion of functional explanations in biology and especially of their relationships to evolutionary ones is an unfortunate shortcoming in this volume, but not everything could be included. And again here is an interesting and important topic for future workers.

The autonomy of biology and the question of the reduction of biology to the physical sciences are quite correctly of great concern to Mayr. Unfortunately these points, which are so self-obvious to anyone working with whole organisms, are completely ignored, forgotten or never realized by many, perhaps most, working biologists today. Entire departments of biology, such as my own, have changed into ones of molecular and cellular biology with the belief that all biology can be completely understood on these levels of organization as well as completely reduced to explanations in the physical sciences. Mayr's strong position to the contrary on both points is an excellent antidote to this widespread but narrow thinking in modern biology, and should be carefully considered by professional biologists and laypersons alike.

Of even greater importance is Mayr's position that a philosophy of science based on physics is simply too narrow to be valid. This is not to claim that a philosophy of science based on physics is incorrect—quite the contrary. Rather such a philosophy is just incomplete. Physics is a simple science largely because of the apparent decision of physicists to restrict their science to nomological-deductive explanations. Nothing is wrong with that, as physicists have every right to decide what to include in their science. Possibly there are no historical events within physics proper, although I doubt it. But by excluding historical-narrative explanations, physicists have established a rather artificial boundary for themselves, and in doing so have lost all claims that physics is the proper science on which to establish a sound philosophy of science.

Mayr advocates the strong position that biology is a better science on which to develop further a philosophy of science, mainly because biology possesses a major component of historical-narrative events that must be explained along with the nomological principles. Biology is not unique in this aspect, as geology and astronomy also have a large component of historical-narrative events, but I agree with Mayr that biology constitutes a far more interesting foundation for the further development of the philosophy of science. Biologists in general have concerned themselves little with the philosophical or methodological foundations of their science, an approach that has been to the detriment of biology. What comes through loud and clear from this entire volume are continuing problems in biological understanding because of this overall lack of interest by biologists in the philosophical foundations of their discipline. In spite of the intense interest during the past quarter century by younger philosophers of biology, we are only seeing the first and very tentative foundations of an expanded philosophy of science. This is a most exciting area for the future understanding of biology to which theoretical biologists will contribute as much as philosophers of science. Mayr points out a number of important areas, such as the role of the genetic program during ontogeny, the central importance of population thinking, and interactions between functional and evolutionary explanations—that is his proximal and ultimate causation—that will have central roles in this development of an enlarged philosophy of science.

This Is Biology is a most fascinating book because it is not a perfectly finished work. Mayr knows well enough that it is not possible to deal with all of the intricate details of so complicated a discipline as biology in a single volume and has not attempted to do so. He has focused on the highlights and points out possible avenues for further thought; indeed there is stimulus for much thought hiding on almost every page of this book. Mayr's clear writing style permits the reader to grasp the core of what is being advocated and hence to be able to think further on the topic. I found much to think about on my first reading of This Is Biology, and even more on the second and third. This is a volume of importance for anyone with the slightest interest in biology, and one that gains ever more importance with one's increasing interest. It is not a book for light bedtime reading, but one for concentration and contemplation. The rewards are great, however, making This Is Biology a pleasure to recommend without reservations to the layperson, the general scientist and the professional biologist alike.—Walter J. Bock, Biological Sciences, Columbia University