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.
Given Some Careful Revision,
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.
This Book Could Be Excellent
William Z. Lidicker, Jr.
In its eighth edition, the BSCS Green Version remains a good
introduction to biology, and its ecological approach to studying the
living world should be strongly encouraged. However, I am
disappointed to find that the book is marred by many inconsistencies
and contradictions -- probably because many individuals have
contributed new material over the years, and the new material has not
been fully integrated with the old.
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
In its overall organization, BSCS Biology: An Ecological Approach is
an admirable text. It is divided into five major sections, and the
first of these -- titled "The World of Life: The Biosphere" --
establishes the book's emphasis on ecology by introducing a number of
ecological principles. The other sections are "Continuity in the
Biosphere" (covering cell biology, reproduction, development, genetics
and evolution) "Diversity and Adaptation in the Biosphere" (dealing
with classification and a survey of the kingdoms), "Functioning
Organisms in the Biosphere" (devoted chiefly to the physiology of
humans and of flowering plants) and "Patterns in the Biosphere"
(about behavior, paleontology, biomes, aquatic ecosystems, and
"human-affected ecosystems"). That all five sections display
"biosphere" in their titles seems contrived; "biosphere" is
appropriate only in the titles of Section One and Section Five.
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.
Defects in the Artwork
While the book's basic framework and conceptual content are
commendable, this does not mean that all is well. Awkward
statements, contradictions and typographical errors are all too
frequent. Sometimes a passage ends with a nearly meaningless
paragraph, suggesting that someone made a crude attempt to prune a
longer discussion of the same topic but didn't know how to tie up the
loose ends. And errors abound, both in the illustrations and in the
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
- 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
- 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
- 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?
Mistakes in the Text
There are many, many errors, confusing misstatements, and obsolete
claims in the book's text as well. I cannot catalogue all of them
here, but I can alert teachers by citing a few examples:
- 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
- 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
- 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
- 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
- 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
- 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.
I would like now to examine the book's treatment of evolution, and of
natural selection in particular. An understanding of evolution is
fundamental to all of biology, and natural selection is a critical
component of the evolutionary process, yet the presentation of these
topics is often one of the weakest aspects of biology education, at
all levels. BSCS Biology: An Ecological Approach is pervaded by
material about evolution, just as it should be, and the material
generally is good. In my view, though, it is not as good as it could
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
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
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
Maybe Next Time
My final comment concerns the book's treatment of conservation. At
appropriate places throughout the text, the writers have inserted
passages about the need for conservation, but their material appears
unduly narrow. For the most part, it is limited to remarks about the
preservation of wilderness areas and about captive-breeding programs
in zoos (complete with embryo transfers and other high-tech
procedures). I hope that, in their next edition, the writers will do
more to show that the conservation of biodiversity is inherently
valuable for promoting human survival and well-being.
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
BSCS Biology: An Ecological Approach -- the new edition of the BSCS
Green Version -- tries to view the biosphere and the science of
biology through an ecological lens. Because I am a plant ecologist, I
applaud this approach.
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
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
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!
Carelessness and Errors
My most serious overall criticism of BSCS Biology: An Ecological
Approach is that it presents too much material, too much jargon, and
too many terms. There is about enough material here to support
separate courses in plant biology, animal biology, cell biology, and
introductory ecology! It must be a nightmare for a high-school
teacher to have to pick, from a book like this, the material that
students can actually try to learn.
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
- 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
- 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.
Some of the mistakes that I have just cited may seem minor. There is
nothing minor, however, about the book's confused mishandling of
homeostasis -- one of the bedrock concepts of biology.
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
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
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
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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