Reviewing a science book for high-school honors courses

Biology
Fourth edition, 1996. 1206 pages + appendices. ISBN: 0-8053-1957-3.
The Benjamin/Cummings Publishing Company, 2725 Sand Hill Road,
Menlo Park, California 94025.

This Impressive Textbook
Is Strongly Recommended

William Z. Lidicker, Jr.

In various cases, Campbell anticipates misconceptions that students sometimes bring with them into the classroom, as well as questions that can arise in the students' minds as they read. For example: In his exposition of evolution, he points out that the fact of evolution is logically separable from any putative mechanism of evolution. He thus refutes the common misperception -- so often fostered by inferior middle-school and high-school books -- that evolution and natural selection are the same thing. He also calls attention to the difference between maladaptive and nonadaptive changes (page 421), and he refutes the popular misconception that evolution leads to perfection (page 433).

It may be hard to imagine that a 6.5-pound book filled with detailed material can be a joy to read, but this one is.

Chapter 1 of Biology is an introduction in which Campbell sets forth twelve themes that will recur throughout the book:

Life is organized on many structural levels

Each level of biological organization has emergent properties

Cells are an organism's basic units of structure and function

The continuity of life is based on heritable information in the form of DNA

A feeling for organisms enriches the study of life

Structure and function are correlated at all levels of biological organization

Organisms are open systems that interact continuously with their environments

Diversity and unity are the dual faces of life on Earth

Evolution is the core theme of biology

Science as a process of inquiry often involves hypothetico-deductive thinking

Science and technology are functions of society

Biology is a multidisciplinary adventure

After the introduction, Campbell provides 49 chapters that are grouped into eight units: "The Chemistry of Life," "The Cell," "The Gene," "Mechanisms of Evolution," "The Evolutionary History of Biological Diversity," "Plants: Form and Function," "Animals: Form and Function" and "Ecology."

When it isn't feasible to cover the entire book, a high-school teacher will be able to build a powerful course by using only chapter 1 plus two or three chapters from each of the eight units. This is appropriate because Campbell's recurrent themes provide coherence and connections among many discrete topics.

Having declared that "Evolution is the core theme of biology," Campbell succeeds in making it the core theme of his book. Moreover, he does this with skill. Read, for example, the opening lines of his chapter 37 ("Animal Nutrition") and see how he unobtrusively puts the entire subject of nutrition into an evolutionary context.

Of course, no book can treat every new bubble of intellectual activity in the biological sciences, but I am a little disappointed to find that there is no explicit description of the recent explosive developments in conservation biology and in landscape ecology. (Landscape ecology is the study of the interactions between different communities at places where they meet -- e.g., where a cornfield meets a forest, or a forest meets a marsh.) Still, Campbell's overall treatment of ecology is superior work. It is refreshing to find that he covers environmental issues at various places in the book, including all the chapters in Unit 8. He does not isolate them, as many other authors do, in an afterthought chapter about "human ecology."

Campbell is particularly successful in his efforts to portray science as a continuing human adventure. He begins each of his eight units by presenting a lengthy interview with a research biologist, and he often discusses the historical development of important concepts. (His account of Mendel's contributions, in chapter 13, is especially well done and informative.) Even more impressive are his reminders that biology is rich in unanswered questions, a point that he underscores with phrases such as "Lively debate continues" or "Currently, biologists think that . . . ."

To his credit, Campbell doesn't attempt to avoid the philosophically difficult issue of reductionism versus holism. Instead he addresses it with understanding, and links it to the theme of emergent properties, in his opening chapter:

Because the properties of life emerge from complex organization, scientists seeking to understand biological processes confront a dilemma. One horn of the dilemma is that we cannot fully explain a higher level of order by breaking it down into its parts. A dissected animal no longer functions; a cell dismantled to its chemical ingredients is no longer a cell. According to a principle known as holism, disrupting a living system interferes with the meaningful explanation of its processes. The other horn of the dilemma is the futility of trying to analyze something as complex as an organism or a cell without taking it apart. Reductionism -- reducing complex systems to simpler components that are more manageable to study -- is a powerful strategy in biology. For example, by studying the molecular structure of a substance called DNA that had been extracted from cells, James Watson and Francis Crick deduced, in 1953, how this molecule could serve as the chemical basis of inheritance. The central role of DNA was better understood, however, when it was possible to study its interactions with other substances in the cell. Biology balances the pragmatic reductionist strategy with the longer-range objective of understanding how the parts of cells and organisms are functionally integrated. [page 4]

The concept of emergent properties in the chemistry of life makes an impressive reappearance in chapter 6, "An Introduction to Metabolism." This chapter also has an excellent treatment of thermodynamics -- a topic which has fundamental importance in biology but which is badly muddled (or ignored altogether) in most introductory textbooks.

Like all the biology books that we see these days, this one is elaborately illustrated, but the illustrations in Biology are not mere adornments. They have been designed to be informative and explanatory. Figure 12.2, for example, is clever, absorbing and educational at multiple levels. Four small photographs show two sets of human parents, while four more photographs show sons and daughters that those parents have produced -- and now the student is asked to match the parents to their respective offspring. In trying to do so, the student confronts several aspects of heredity and sexual reproduction.

Another notable illustration is figure 4.8. Here, structural diagrams of the sex hormones estradiol and testosterone are flanked by photos in which male and female wood ducks display their striking sexual dimorphism. Here again there are multiple lessons, the most obvious of which is: Subtle differences in molecular architecture can produce profound differences in development, physiology and behavior.

• Page 406: In "Observation #1," Campbell writes "fertility" when he means fecundity.

• Pages 419-421: In his discussion of the Hardy-Weinberg equilibrium, Campbell implies that evolution must always occur -- i.e., there must always be some generation-to-generation changes in gene frequencies -- if natural selection is operating. That is not accurate. If, as an example, the selective pressures favor homozygotes over heterozygotes, a population's genotypic frequencies can remain stable, even though the population is not in Hardy-Weinberg equilibrium.

• Page 425: "Notice again," Campbell says, "that nonrandom mating -- inbreeding or assortative mating -- increases the number of gene loci in the population that are homozygous, . . . ." That is true only for positive nonrandom mating, in which an organism chooses mating partners that resemble itself. In negative nonrandom mating, an organism choose mating partners that differ from itself -- and this promotes a reduction, not an increase, in homozygosity.

• Page 443: Campbell twice confuses the terms dispersion and dispersal. Dispersion is a description of how organisms are arrayed in space. Dispersal is a process in which individuals leave their homes and spread to new locations.

• Page 638 (figure 30.11): It is misleading to say that the adipose fin is "characteristic of trout." Adipose fins occur in other salmonid fishes as well, and also in bony fishes belonging to some other families -- e.g., the catfishes.

• Page 651: Here and on some later pages, Campbell uses "placental mammals" to designate the eutherians, implying that marsupials lack a placenta. In fact, however, all marsupials have a placenta that is equivalent in complexity to the placenta of the eutherians. Campbell also perpetuates the common, erroneous belief that all marsupials have pouches. (In reality, only about half of them do.) And Campbell conveys a false impression when he casually writes that "The opossums of North and South America are the only extant marsupials outside the Australian region." That statement masks the wonderful diversity of the New World marsupials: Our hemisphere has at least 75 marsupial species, which are arranged in nineteen genera and three families. (The family Microbiotheriidae comprises just one species, Dromiciops gliroides. This highly distinctive, arboreal marsupial inhabits temperate rain forests in Chile and Argentina, where it is known by the vernacular name monito del monte -- the "little monkey of the mountain.")

• Page 654: Not all bats are insectivores, frugivores or vampires. Some bats are carnivores, others make a living by catching fish, and still others feed on pollen.

• Page 883: "[K]angaroo rats lose so little water that they can recover 90% of the loss by using metabolic water . . . ." That's true, but it carries a misleading implication. The student needs to understand that all mammals exploit metabolic water, and that the kangaroo rat is not unusual in this respect. What makes the kangaroo rat extraordinary is that metabolic water can supply such a high percentage of this animal's water requirement.

• Page 940: The "toad" in figure 42.4 is the common European frog Rana temporaria.

• Page 1,080: Grizzly bears are not typical inhabitants of coniferous forests.

• Page 1,081: Blackflies and mosquitoes are more typical of the taiga than of the tundra.

• Page 1,087: Intertidal zones are inhabited by bryozoans, not by bryophytes.

• Page 1,098 (in table 47.1): For both the males and the females, the "proportion of cohort dying" in year 8 should be 1.0.

• Pages 1,121-1,130: In his section about interspecific interactions, Campbell ignores one of the most common symbiotic relationships: amensalism. He says that commensalism is rare ("Few absolute examples of commensalism exist"), but this is not so. He also overlooks indirect interspecific interactions, although ecologists now appreciate that these can be very important in nature. As an example of indirect interaction, consider a situation in which species A and species B are competitors, and both A and B are prey for some predator. If the predator diminishes the population of species B more than it diminishes the population of species A, then the predator may indirectly confer a net benefit on species A. Notice also that this contradicts the conventional idea that predation is always detrimental to a prey species.

• Page 1,179: The small bird in the lower photo is identified as a "reed warbler," but it really is a dunnock (Prunella modularis).

• Campbell uses the term ecosystem in the ambiguous manner that is currently fashionable. In his glossary and on page 4, he says that an ecosystem comprises a community plus its physical environment. This implies that, as far as biological complexity is concerned, ecosystems stand at the same level as communities. Elsewhere, though, Campbell states that ecosystems represent the "most inclusive level in the hierarchy of biological organization," and he thus claims that ecosystems have more biological complexity than communities do. There are at least two problems with such a claim. First, viewing a community as an "ecosystem" does not endow that community with any new biological complexity. The term "ecosystem" merely draws more attention to the interactions between biotic and abiotic components. Second, ecologists have proposed units (such as the landscape, the biotic province, and the biosphere) that rank higher than the community in terms of biological complexity.

• In his listing of interspecific interactions (on page 1,121), Campbell correctly defines competition as an interaction that is detrimental to both species. But then he falls into a trap that has caught many other authors as well: He describes interspecific competition as if it exists only in situations where different species have overlapping demands for some resource that is in short supply. This leads to such unfortunate conclusions as "competition cannot be important unless population sizes are near carrying capacity . . ." (page 1,132). It also inhibits recognition of detrimental competitive interactions which don't directly involve the acquisition of resources. For example, two species of plant may inhibit each other's growth by releasing toxic metabolites. This is a form of competition.

While focusing on ecological matters, I want to add that Campbell's chapter on population biology (chapter 47) is, overall, remarkably good. He includes immigration and emigration in the population-growth equation, he makes a clear and correct distinction between r (a population's actual per-capita rate of growth) and r_max (the population's potential rate of growth under ideal conditions), he recognizes the irony in applying the name "life table" to what is really a tally of deaths, he offers an excellent treatment of human population growth, and he recognizes that density regulation, in most situations, depends on multiple factors.

In This Worthy Textbook,
Nothing Is Dumbed Down

Michael T. Ghiselin

Such role models are appropriate here, for Biology should be regarded as a book for students who are interested in biology as a career and who need a solid knowledge of the fundamentals before they undertake specialized courses in college. This is a worthy text in which nothing is dumbed down and nothing is glossed over as too difficult.

Is the book suitable for high-school students in an honors course or an advanced-placement course? The answer depends in part upon the students. Campbell has put a great deal of biology into Biology, and some students -- even though they are bright, diligent and qualified to take an honors course -- may feel overwhelmed by it.

Wherever I have checked Campbell's material in detail, I have found it to be unusually accurate. There are few errors, and I have not encountered any egregious blunders of the sort that so often occur in inferior books. (Just to prove that I have looked carefully, let me describe one of the few mistakes that caught my eye: In figure 30.2, on page 629, the artist has added an imaginary piece to the gut of a larval tunicate, making the gut extend through the entire length of the animal's tail.)

In general, the mistakes and missteps in this book arise not because Campbell has got things wrong but because he hasn't got things quite right. His historical material, for example, includes a common anachronism: He makes Gregor Mendel's work look more like modern genetics than it really was.

One of the great merits of Biology is Campbell's effort to tie things together by using a few major themes. This helps the reader to strive for something more than the brute memorization that can make biology courses deadly. Evolution is definitely the central theme of the whole book, and Campbell repeatedly draws attention to the utility of evolutionary thinking in making sense of otherwise unintelligible phenomena.

Similarity can be a rather tricky concept, and judgments about similarity are often highly subjective. This leads to the question of how and whether similarity is useful in tracing genealogies and in recognizing common ancestries. Systematists are not of one mind about how we should go about the task of classifying organisms, and the systematists' controversies can be confusing to outsiders. Campbell provides an adequate treatment of these controversies and tries to explain three major schools of systematic thought. Unfortunately, however, he calls the three schools "phenetics," "cladistics" and "classical evolutionary systematics." This nomenclature isn't quite right.

Phenetics isn't a kind of systematics. Phenetics is the study of similarity. It is a field of scientific inquiry, like genetics or embryology. When Campbell says "phenetics," he actually is referring to pheneticism, a school of systematics which had its heyday during the 1960s and which revolved around the doctrine that classifications should be based strictly upon observed similarities.

Cladistics, too, is a field of study -- the study of biological lineages or genealogies. When Campbell says "cladistics," he really is referring to cladism, a style of systematics in which classification is strictly genealogical.

As for "classical evolutionary systematics": This is a school of systematics that represents a sort of middle position between pheneticism and cladism. Its practitioners incorporate both phenetic and cladistic criteria into decisions about classification.

The classification system that usually is taught to beginning students presents a real problem because it is based on a mixture of cladistic criteria, phenetic criteria, and old traditions. One of these traditions is the notion that we should divide the animals into two equivalent groups called the vertebrates and the invertebrates. This fancy, which goes back to Lamarck, is rather like dividing the residents of the United States into two groups called "New Yorkers" and "others." The invertebrates are the "others" that remain after we subtract the vertebrates -- the group to which we ourselves happen to belong -- from the rest of the animals. They don't have any common feature that is scientifically interesting or meaningful. Although Campbell emphasizes that more than 95% of all the animal species are invertebrates, he adheres to the equal-space tradition that textbook-writers have always followed: one chapter for the invertebrates, then one chapter for the vertebrates.

In his chapter about the invertebrates, Campbell makes a heroic effort to get away from the usual, dull listing of taxonomic groups, and he tries to give a précis of the comparative anatomy and comparative embryology that underlie the classification of animals. This leaves him little room for telling about the animals' other properties or their ecological roles, and his attempt to deal with embryology is oversimplified to the point of outright error. In particular, he confuses the distinction between the schizocoela and the enterocoela with the distinction between protostomes and deuterostomes. Let me explain this:

In some animals, the body cavity is a true coelom, i.e., a cavity lined with an epithelial layer made of mesoderm. These animals are called the coelomates, and they are divided into two groups -- the schizocoela and the enterocoela -- according to how the coelom arises during embryogeny. In the schizocoela the coelom forms as a split in the mesoderm, but in the enterocoela the coelom forms as an evagination of the gut. Campbell recognizes that the distinction between the schizocoela and the entercoela is fundamental in classification, but he muddles it with another distinction that is equally important, i.e., the distinction between protostomes and deuterostomes. (This latter distinction, based on how the mouth originates during embryogeny, is so powerful that the deuterostomes -- which comprise the phyla Chordata, Echinodermata and Hemichordata -- are viewed as a separate branch of the animal kingdom.) In trying to make things simple, Campbell treats the protostomes as if they all were schizocoela, but this is just wrong. Many protostome groups do not even have a true coelom.

When he focuses on our own phylum, the Chordata, Campbell rightly cites three diagnostic characters -- the notochord, the dorsal, hollow nerve cord, and the postanal tail. But then he adds a fourth character: the presence of pharyngeal slits. This is a mistake, for pharyngeal slits aren't unique to the Chordata. Pharyngeal slits are also present in the Hemichordata, a phylum that isn't even mentioned in Campbell's book.

All in all, the chapter on vertebrates is more satisfactory than the one about invertebrates: It does not concentrate so heavily on classification, and it gives more information about form and function. For example, Campbell explains how vertebrate jaws have arisen through modification of earlier structures. But even so, this book -- like so many others -- perpetuates the impression that the essential reason for studying biology is the need to understand humans.

In his efforts to describe biodiversity, Campbell is more effective when he deals with the plants and the fungi than when he deals with animals, because he conveys a better appreciation of the various roles that the plants and fungi play in the economy of nature. If he wanted to present the animals in a comparable way, he would have to add another chapter or two about the invertebrates, emphasizing how these immensely diverse animals live their lives and how they fit into the natural world.

William Z. Lidicker, Jr., is a professor emeritus in the Department of Integrative Biology at the University of California at Berkeley, a curator emeritus of mammals in that institution's Museum of Vertebrate Zoology, and a fellow of the California Academy of Sciences. His research deals with the evolution, ecology and conservation biology of vertebrates.

Michael T. Ghiselin is a biologist, a senior research fellow at the California Academy of Sciences, and chairman of the Academy's Center for the History and Philosophy of Science. His research has emphasized comparative anatomy and the evolution of modes of reproduction. His books include The Triumph of the Darwinian Method and The Economy of Nature and the Evolution of Sex.

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