Reviewing a high-school book in biology

BSCS Biology: An Ecological Approach
1998. 774 pages. ISBN of the student's edition: 0-8403-9659-7.
Copyrighted by Biological Sciences Curriculum Study
(Colorado Springs, Colorado). Published by Kendall/Hunt
Publishing Company, 4050 Westmark Drive, Dubuque, Iowa 52004.

Editor's Introduction -- Kendall/Hunt's BSCS Biology: An Ecological Approach is the eighth edition of the book that is commonly called the BSCS Green Version, or simply "the BSCS Green." Earlier editions, the most recent of which was dated in 1992, carried the title Biological Science: An Ecological Approach. Two reviews of the 1992 edition appeared in The Textbook Letter, July-August 1992. All in all, the eighth edition closely resembles the seventh -- and as you will read in the reviews below, it contains factual errors and other defects that were present in the seventh edition and that haven't been corrected. The innovations in the eighth edition appear to consist chiefly of new typography, new color schemes, and some sales-promotion gimmicks. One gimmick is a faddish "Foreword," with some hype that tries to link the book to "national standards" and "benchmarks." (This "Foreword" appears in the student's edition, though it speaks only to the teacher.) Another gimmick, apparently concocted to provide some political correctness, is a silly article about a blind man who "has risen above his physical restrictions" to become "a premier level paleontologist and editor of Evolution, the field's most prestigious journal." There is no explanation of how a blind man can work as an editor of anything -- and the claim that Evolution is a paleontological journal is false. This article seems significant because earlier editions of the Green Version weren't sullied by such rubbish.

Given Some Careful Revision,
This Book Could Be Excellent

William Z. Lidicker, Jr.

I am further distressed to see that this eighth edition suffers from grossly incompetent editing. When Stuart H. Hurlbert reviewed the seventh edition for The Textbook Letter, he politely concluded that it was a worthy book but it needed considerable refinement. Unfortunately, Kendall/Hunt's editors have not heeded his criticism. In most cases, they haven't even corrected the errors that he identified.

At the conceptual level, this book is strong. Topics such as evolution, the growth of the human population, and environmental deterioration are handled without apology or compromise. In chapter 2, when the writers consider the variables that affect population size, they include immigration and emigration -- factors that often are omitted by the writers of other introductory books. In chapter 3, the writers properly acknowledge the importance of cooperative (positive) interactions and indirect interactions among species. Chapter 8 has a good discussion of probability. Chapter 20 offers a solid treatment of the dichotomy between innate behavior and learned behavior. And in general, the writers succeed in conveying the open-ended, exciting nature of science.

The book concludes with four appendices. One of these is an illustrated "Catalog of Living Things" that, for some groups, goes down to the level of families. This is an extremely useful feature, although it is not free of errors.

The illustrations in BSCS Biology: An Ecological Approach are abundant but of inconsistent quality. Some are excellent -- e.g., figure 13.33, "Comparison of monocot and dicot characteristics" -- but many others act as decorations only. They are too small to disclose important features, they are inadequately explained, they contain errors, or they have erroneous captions. A handful of examples will serve to show that Kendall/Hunt's illustrators and editors have not paid adequate attention to their artwork:

• On the opening page of Section One, an image of Earth is shown in unexplained false colors, and the caption asks an unanswerable question.

• Page 7: The text directs our attention to figure 1.4, where "A small bird feasts on the fruit near the top of the bush." But the small bird is a chickadee, and chickadees are insectivorous.

• Figure 5.2 comprises two photographs of epithelial cells, obviously shown at the same magnification. The magnifications given in the caption are "X400" for one photograph, "X1000" for the other.

• Figure 6.4 shows a human ovum and a rat ovum looking like small chicken eggs!

• Figures 7.9 through 7.11 illustrate human embryos. All three figures have mistakes, including a misspelling of karyotype and an erroneous labeling of the extra-embryonic membranes.

• Figure 8.21, illustrating nondisjunction, contains six errors! For example, an XXY individual is labeled "XXX male"; abnormal sperm cells, lacking sex chromosomes, are turned into "XO female" individuals, even though the sperms haven't united with ova; and erroneous labels indicate that some (but not all) of the "XO female" individuals are inviable.

• Figure 9.9, which deals with Galápagos finches, is divided into two parts that have no evident relation to each other. The upper part comprises sketches of thirteen finches that are labeled with their common names only, while the lower part is a diagram involving ten finches that are denoted by their scientific binomials only. The student is left to wonder which finch is which. The caption gives no help, and it refers to the tool-using finch as the one "at the top right"; actually, the tool-using finch is shown at the lower left.

• The caption for figure 9.17 is wrong. The Kaibab squirrel is the animal on the right.

• Figure 9.18, "Adaptive radiation of mammals," is disgraceful. It is so badly obsolete that it seems to date from the original edition of the Green Version, and it shows two mammalian orders floating alone, unconnected to the others.

• In figure 10.6 Thomomys is spelled in two ways, and a ground squirrel still retains a generic name (Citellus) that has been invalid for about 40 years.

• Figure 10.30: The upper teeth of a chimpanzee have been assigned to a gorilla, and vice versa.

• In figure 11.25, the genetic material in a retrovirus is wrongly labeled "viral DNA," instead of "viral RNA." This mistake compromises the message of the entire figure.

• Figure 13.1: The common name for the Sequoiadendron shown in the photo is "bigtree" or "giant sequoia" -- not "redwoods."

• Figure 14.15, showing a "life cycle," lacks the critically important arrow that should connect the adult to the egg.

• Figure 14.28: Some anatomical structures are numbered, but the caption does not explain the numbers or identify the structures.

• Figures 15.3 and 17.4, both pertaining to human anatomy, are sloppy, uninformative drawings for which there is no excuse. For example, in 15.3 the large intestine is called "stomach" and trypsin is misspelled. In 17.4 the "thoracic vertebrae" label points to the sternum, and the head of the humerus is labeled "scapula."

• Figure 21.10 includes six images of our planet during the "formation and breakup of Pangaea," but the first three images are inverted with respect to the other three. The same figure has an unacceptable representation of bird evolution. It shows a discrete lineage of birds arising in the late Permian instead of in the mid-Jurassic.

• Figure 22.3 cannot be understood without attention to Earth's axis, but the axis is almost invisible and north is not indicated.

• Figure 22.13 incorrectly labels the least chipmunk as an animal of "the deciduous forest."

• Figure 22.15a shows not one species of macaw but two -- the scarlet macaw, Ara macao, and the blue-and-yellow macaw, A. ararauna.

• The scene in figure 22.27 ("Tropical deciduous forest") is the same as the scene in figure 3.16 ("Tropical rain forests"). Which label is right?

• On page 25, population is categorically defined as a "group of interbreeding individuals of the same type that live in a particular area." That adjective "interbreeding" should be deleted. A given population may be unisexual or asexual, or it may consist of individuals that are not in their breeding phase, but it is still a population.

• Page 32: The global human population is given as 5.3 billion instead of 5.9 billion.

• Page 54: A community's gross primary productivity is defined as the "total amount of chemical energy stored by photosynthesis." In fact, however, the gross primary productivity is the total amount of energy that is fixed. The net primary productivity is the amount that is stored. The net productivity always is less than the gross productivity, because some of the gross is consumed by the producers themselves.

• Page 62 has an unexplained claim that "the Andean condor has been successfully reintroduced." This seems to be a muddled reference to an attempt to reintroduce the California condor -- an effort that cannot yet be deemed successful, because a breeding population has not yet been established.

• Page 102: The maximum size of eukaryote cells is given as 100 micrometers instead of 2 meters or so.

• On page 164 Gregor Mendel is said to have worked at a monastery "in Austria." Students will doubtless take this to mean the Austria of today. In fact, Mendel's monastery was at the town of Brünn, in the Austro-Hungarian Empire. Today that town is called Brno and is in the Czech Republic, not in Austria.

• Page 229: The number of described species is said to be "more than 1.4 million," but it actually is more than 1.7 million.

• Page 353: The claim that birds "have the greatest motility of any animal" is compromised by what we know of fishes, marine mammals, bats, humans, and many insects.

• Page 354: The marsupials are defined here (and in the glossary) as mammals whose young develop in pouches. That is not an acceptable definition, because only about half of all the marsupials have pouches.

• Page 355 is devoted to an article, titled "Marsupials and Monotremes," that conveys much misinformation. For example, the article implies that birds do not employ internal fertilization -- but in fact, they do. The article implies that fertilization of eggs in the oviduct is a special feature of reptiles and platypuses -- but in fact, this is the typical condition in all vertebrates that use internal fertilization. The article says that there are only two living species of monotremes -- but there are five.

• Page 364: "In fishes and amphibians, fertilization occurs externally, and the zygote develops in the water." In reality, many amphibians and many fishes, including all the elasmobranchs, have internal fertilization.

• Page 544: The writers imply that evidence supporting the idea of continental drift did not begin to accumulate until 20 years ago. Continental drift has been generally accepted among scientists for at least 40 years.

• Page 550: The earliest amphibians did not resemble "salamanders and snakes."

• Page 552: The categorical claim that primates have "nails rather than claws" is false. Only the anthropoid primates have nails.

• Page 551: A sketch of an Australian lungfish indicates that the fish's actual length is some 10 centimeters. An accurate estimate would be about ten times greater than that.

• Page 721: Porcupines are not lagomorphs.

• On page 729, in the book's glossary, cooperative behavior is defined as "behavior that reduces the reproductive fitness of the performing individual and increases the fitness of the recipient." That actually is a definition of altruistic behavior. Cooperative behavior yields benefits to both participants.

The principal exposition comes in chapter 9, "Continuity Through Evolution," which puts so much emphasis on Darwin that the field of evolutionary biology seems to be a one-man show. This is not a realistic image.

The chapter's formal definition of evolution, given on page 208, is unfortunate: "a change in a species or population through time." But populations continuously undergo changes which are not evolutionary -- changes in size, density or distribution, for example -- so a correct definition of evolution must specify genetic change. Another goof is the equating of assortative mating and sexual selection (page 211). These two processes are quite distinct, though both processes involve the choosing of mates.

Turning now to the book's treatment of natural selection, we note that this phenomenon is defined in three ways, and all three definitions are inadequate. In the main text, on page 206, we read that natural selection is "the process by which those characteristics that permit survival and reproduction are continued and eventually replace less advantageous characteristics." This is awkward and trivial. The statement that traits which do not permit survival and reproduction will be replaced (by those that do) hardly suggests any profound insights. In the chart on page 223, natural selection is simply equated to differential survival; reproduction is not mentioned. In the glossary, on page 737, there is a better definition that at least captures the idea of differential survival and reproduction among members of a population and ties these results to adaptations.

In my view, the process that we call natural selection has two critical features that students must grasp. The first is that the individuals in a population are not equally successful in passing their genetic material to future generations. The second is that the disparities in success are not random with respect to the individuals' genetic endowments. Some individuals, because they carry certain genes, will be more successful in a given environment. They will make a disproportionately large contribution of genes to the next generation, and (on average) the population's level of adaptation to that given environment will improve. Success is not merely survival and reproduction. Success means producing offspring that will produce successful offspring that will produce successful offspring . . . and so on, into the future.

So far, the selection scenario is rather simple, but now we must add the point that the individual's environment is constantly changing. The environment's biotic and abiotic components inflict a dynamic mix of influences on the entire population, and the population provides a variable genetic context for each individual. As an example: A male in a population that consisted mostly of females would experience selective forces quite different from the forces acting on a male in a population that consisted mostly of males. Moreover, short-term gains in fitness can carry a penalty in the form of an inability to adapt to some future alteration in conditions. Nevertheless, natural selection is the one evolutionary mechanism which ties genetic composition to the environment and, therefore, can lead predictably to improved adaptations.

We should accept nothing less than excellence in our biology textbooks, since the scientific literacy -- and specifically, the biological literacy -- of our citizenry is at stake. BSCS Biology: An Ecological Approach has a chance of making the grade. Taken as a whole, it already is an impressive production. With a healthy dose of loving care and attention, it could be terrific.

Many Commendable Aspects,
Much Room for Improvement

Wanna D. Pitts

When I taught plant biology to college freshmen, the course began with topics that were familiar to students, then expanded to embrace matters that the students probably had not encountered before. In BSCS Biology: An Ecological Approach, the first of the book's five principal sections reflects a similar strategy. The section is called "The World of Life: The Biosphere." Its first chapter, "The Web of Life," starts with information that already is known to everyone: Some organisms "interact" with other organisms by eating them. This leads to a more formal examination of how organisms obtain and use energy. Then, as the scope of the section expands, the student reads chapters titled "Populations," "Communities and Ecosystems" and "Matter and Energy in the Web of Life."

Section Two of the book is called "Continuity in the Biosphere," and the titles of its five chapters have been chosen so that "continuity" appears in each: "Continuity in Cells," "Continuity Through Reproduction," "Continuity Through Development," "Continuity Through Heredity," and "Continuity Through Evolution." This is a stretch, but the sequence is not flawed, and the chapters themselves generally present information in a clear manner.

The three remaining sections are "Diversity and Adaptation in the Biosphere," "Functioning Organisms in the Biosphere" (including three chapters on "The Human Animal"), and "Patterns in the Biosphere." This last section is very broad, with chapters titled "Behavior, Selection, and Survival," "Ecosystems of the Past," "Biomes Around the World" (yes!), "Aquatic Ecosystems," and "Managing Human-Affected Ecosystems."

As a whole, BSCS Biology: An Ecological Approach is a good text. As a whole, it's well written, and the graphics are excellent. The text has a Socratic flavor, often presenting questions that impel students to think about the matters at hand. Indeed, almost every chapter opens with a photograph and several questions (pertaining to the photo) that foretell some of the science that the chapter will teach. Chapter 2, for instance, starts with a photo of some king penguins, and the caption says:

A population is a group of organisms of the same species that live and interact in the same place at the same time. What is the evidence of a population in this photo? What is the evidence that the penguins are the same species? Identify some of the variations among individuals. How can the penguins have these individual variations and still be a population?

In teaching about the processes of science, this book offers a strong, hands-on approach. Every chapter has at least one "Investigation," and most chapters have two, three or four. Another strength is the continual attention to the effects of humans on the rest of the living world. The student learns that we humans exert major forces on our planet's health, and one proposition stands out clearly: All environmental issues are connected to the growth of the human population.

There is very little equivocation. The passages about topics such as birth control, deforestation, global warming, venereal disease and water pollution seem refreshingly frank. I particularly admire the clear, uncompromising discussion of birth control in the "Biology Today" article on page 135.

Of the book's four appendices, my own favorite is "Appendix Four: A Catalog of Living Things." Here, in fewer than thirty pages, is a beautifully illustrated compendium of the living world. Well done!

My specific criticisms focus on factual mistakes, on instances of carelessness, and on the inadequate handling of two major topics: homeostasis and natural selection. Let me start by citing some cases involving carelessness or outright errors of fact:

• In figure 2.4, the flower labeled "blazing star" is unlike any blazing star that I ever have seen, and it closely resembles a clover. The caption for figure 2.4 has a vague reference to how organisms are "distributed," but there is nothing in the text to help a student consider the ramifications of the actual distribution of any organism.

• Chapter 3 opens with a splendid picture of an ant tending aphids on the surface of a plant, and the caption asks: "Is any organism harmed?" Then the student is directed to cite other examples of relationships "in which neither party is harmed." Doesn't anyone think that the plant may be harmed?

• In chapter 3 the student reads this definition: "The niche of an organism is its role in the community: what it eats, what organisms eat it, and what indirect relationships it has with organisms," but the glossary defines niche as "the total of an organism's utilization of the biotic and abiotic resources of its environment." These contradictory definitions -- which will certainly cause students to become confused -- are the same ones that Stuart H. Hurlbert found when he reviewed the seventh edition of the Green Version. (See The Textbook Letter, July-August 1992.) Why have they now been carried into the eighth edition?

• Figure 5.4 consists of photomicrographs of "eukaryotic plant cells in a pine needle" and an unidentified "prokaryotic cell." The caption commands the student to "Notice generally more complex structure in the eukaryotic cell," but the micrograph of the "prokaryotic cell" is incomprehensible (because of its low magnification) and does not show any "structure."

• Figure 9.3 shows a mule that produced two foals. This doesn't do anything to "illustrate the difficulty in defining a species," though the caption claims that it does.

• In the "Biology Today" article on page 355, a comparison of reproduction in monotremes and birds implies that monotremes use internal fertilization but birds do not!

• Page 392: "Most Americans exceed the protein requirement of 0.5 to 0.8 per kilogram of body weight per day." My question is: 0.5 to 0.8 what?

• Figure 23.22 is said to be a photo of "A tide pool community including sea stars, Piaster ocuraceus, rockweed and barnacles." The real name of the sea star in question is Pisaster ochraceus. The caption-writer has misspelled both words. Furthermore, only two sea stars appear in the picture, and the barnacles (if any are present) cannot be discerned. The scene actually is dominated by sea urchins (Strongylocentrotus sp.) and anemones (Anthopleura sp.).

• Page 630 says that eutrophication is the "process" by which "ponds and lakes suddenly turn green at various times of the year, fish die, and the water smells bad." This is the dumb definition of eutrophication that appeared in the seventh edition. Why has it not been corrected?

• Page 636: Here is another howler that has been retained from the seventh edition. The text says that our ancestors' brainy ways of coping with their environments were cultural, "not biological," adaptations. How can anything that organisms do be "not biological"?

• Page 647: "Each environmental issue has unique, local aspects, in addition to biotic, abiotic, and social aspects." As Stuart Hurlbert remarked when he found that same double-talk in the seventh edition, the implied distinctions are false and will bewilder students. The local aspects of an issue do not exist "in addition to" its biotic aspects, or separately from its social aspects. The local aspects of an issue typically include its biotic, abiotic and social aspects.

The term homeostasis is introduced on page 29, where it is flatly defined as "the tendency for a population to remain relatively stable in size." This definition may be acceptable in some circumstances, but it certainly does not reflect the primary meaning of homeostasis in the vocabulary of biology. The definition given in the book's glossary -- "the tendency for an organism, or a population of organisms, to remain relatively stable under the range of conditions to which it is subjected" -- is equally eccentric.

Not until page 428 do the BSCS writers even hint at the most common meaning of homeostasis, i.e., an organism's capacity to maintain relatively constant internal conditions in spite of alterations in the external environment:

The cells of the human body are surrounded by a liquid that is remarkably constant in its properties. The continuous regulation of the many dissolved compounds and ions in this internal environment is referred to as homeostasis.

Even here, what the writers say is so narrow that it is misleading. Homeostasis, in its physiological sense, refers to a good deal more than just the regulation of "the many dissolved compounds and ions" in an intercellular liquid.

Homeostasis receives one more brief mention on page 443, where the writers say, "Even before you were born, the endocrine (EN doh krin), or ductless, glands and the hormones they secrete were functioning in the homeostatic control of your body." And that's all for homeostasis.

When the seventh edition of this book was reviewed in The Textbook Letter, David Cobb remarked that the writers had failed to view homeostasis as a fundamental characteristic of living systems. In the eighth edition, they have failed again.

The writers' account of evolution by natural selection is uneven and unsatisfactory. Page 223 has a good summary of the work of Charles Darwin, but some of the earlier material about Darwin is poor. On page 205, for example:

During his studies, Darwin came across an essay by Reverend Thomas Malthus (1766-1834) that warned about the dangers of human overpopulation. . . . Darwin applied [Malthus's] idea to his own work and concluded that most species have a high reproductive potential but not all individuals reproduce. Populations, he argued, are kept in check in part because some organisms fail to reproduce.

That emphasis on the idea that some individuals "fail to reproduce" is misleading. Darwin saw that the production of more individuals than the environment can support engenders a "struggle for existence" among members of a population, and that only a fraction of the offspring produced in each generation can survive. This struggle for existence is not a contest in which the winners leave surviving offspring while the losers categorically "fail to reproduce" and leave no descendants at all. The contest is more subtle than that. It revolves around numbers of offspring, and even an individual that leaves surviving offspring can be a loser. The winners are the individuals that, in the long run, leave the greatest numbers of descendants. Darwinian fitness, then, is usually a matter of relative, not absolute, reproductive success. It seldom is the all-or-nothing business implied by that phrase "fail to reproduce."

To conclude: BSCS Biology: An Ecological Approach is a good and useful text. It has much room for improvement, however, and I particularly hope that the writers, in their next edition, will clean up all the defects that have been noted here and in earlier reviews.

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.

Wanna D. Pitts is a retired professor of biology from San Jose State University, where her teaching included courses in plant biology, general ecology, plant ecology, biodiversity, and pollination biology. She is a co-author of the third edition of Terrestrial Plant Biology, published by Addison Wesley Longman.

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