A few weeks ago I sent out a proposed letter of response to the National
Association of Biology Teachers' "Statement on Teaching Evolution."
Several of you wrote back to offer encouragement, corrections, and
suggestions for improvement. I have incorporated those suggestions in
the letter below.
I'm writing to invite "electronic signatures" to this letter. If you
wish to sign, e-mail me a short note with your name, e-mail address, and
(if you wish) the institution where you work. I will add it to the end
of the letter. If you wish to forward this letter to other interested
parties, feel free to do so. Barring unforeseen circumstances, I will
send this to the NABT Board of Directors in a few weeks.
Oct 29, 1996
Dear Members of the Board of Directors
of the National Association of Biology Teachers,
Your goal of teaching evolution in an effective, scientifically honest,
and religiously neutral fashion, as stated in your March 15, 1995,
"Statement on Teaching Evolution," is commendable. We share that goal.
We also appreciate the difficulty of providing guidance to biology
teachers on this complicated and politically charged topic. There are
many excellent points in the "Statement on Teaching Evolution;" however,
we believe there are a few points where the Statement fell short of your
goal. We would like to offer some suggestions for future revisions of
this Statement, which we believe will help you achieve this goal.
First, I should explain who "we" are. We (the undersigned) are not
members of any particular organization. We are individuals who have
been studying and discussing the topic of evolution for some time in
various forums. Many of us are professional scientists. We hold a
considerable diversity of opinions about biological history. Some of us
believe that the modern theory of evolution is essentially correct.
Others of us believe that evolutionary mechanisms are limited to
"microevolution" and that additional factors are needed to explain
biological history. Very few of us hold to a "Young Earth" creationist
view, although most of us are creationists in the broad sense of the
term (we believe in a Creator). All of us want to see evolution ---
both the mechanisms of evolution, and the overall theory which attempts
to unify observations from many branches of biology --- taught in an
effective, scientifically honest, and religiously neutral fashion.
We will start by listing several concerns we have with the March 15,
1995, "Statement on Teaching Evolution." Then we will offer some
specific suggestions for minimal revisions in the Statement which we
believe will help it better achieve its purpose.
1. The Statement (particularly the third paragraph) lumps together all
forms of "creation beliefs" into the category of young-earth
creationism. This is inaccurate. There exists a broad range of
creation beliefs. Even within "intelligent design theory" there is a
considerable range of views.
One reason for the continuing controversy over evolution is that only
the polar extreme views (young-earth creationism, and evolution couched
in deliberately atheistic terms) get the attention of the press and the
public. Future revisions of the Statement could help defuse the
controversy by helping to correct that misapprehension.
2. The Statement's description of evolution as an "unsupervised,
impersonal ... process" (paragraph 5) is *not* religiously neutral.
Science is unable to determine whether or not evolution is
Science is capable of describing the observable characteristics of
evolutionary mechanisms. For example: Mutations occur by physical and
biological processes which are not controlled by the organisms
themselves. Mutations can be beneficial, neutral, or harmful to
offspring. Adaptations do not always provide an obvious selective
advantage. Natural selection changes the frequency of genetic variants
based upon currently existing environmental conditions; as such, it does
not always ensure the long-term survival of any species, nor does it
always favor more complex forms over simpler ones.
While each of these mechanisms can be modeled as an purely natural
process, this does not tell us whether the entire evolutionary process
is ultimately supervised or unsupervised. That question goes beyond the
realm of science, into philosophy and religion.
3. The Statement's third paragraph says, "Evolutionary theory, indeed
all of science, is necessarily silent on religion and neither refutes
nor supports the existence of a deity or deities." This is true.
Unfortunately, evolution is not always presented this way. A classic
example of religious non-neutrality is the claim that, "Since science
can explain (mechanistically) how evolution happens, 'God is no longer
necessary.'" We are confident that most biology teachers do not do
this. Yet there are enough examples of these kinds of statements in the
"popular" scientific literature to be concerned about it. Biology
teachers and textbooks might unintentionally fall into this trap simply
by using or referencing such material. It would be helpful if the
Statement addressed this issue briefly.
4. The word "evolution" covers a lot of scientific territory.
"Popular" literature on evolution, and even some textbooks, tend to
jumble together concepts which should be distinct. The Statement could
help to correct this problem by, for example, encouraging that students
should be taught to distinguish amongst  the mechanisms of evolution
(mutation, recombination, natural selection, etc.);  the phenomenon
of genetic changes in present-day populations (sometimes called
"microevolution");  the overall theory of evolution as an explanation
for biological history; and  the data which is used to support
evolutionary theory (the fossil record, genetic and developmental
similarities between species, modern examples of microevolution, etc.).
All four of these categories should be taught, including the ways in
which they interact with each other. However, there are several
benefits gained from teaching students to make these distinctions.
First, it is helpful for understanding how science works in general.
Second, if a student is uncomfortable with the general theory of
evolution for philosophical or religious reasons, this approach may help
the student understand the validity of evolutionary mechanisms and the
nature of the supporting data (rather than, for example, being
suspicious of *everything* associated with "evolution").
5. Science teachers should be willing to explain which parts of
evolutionary theory are well-established and which are more speculative.
It is important for students to learn where scientific theories are
strong, and where they are weaker. Microevolution, the fossil record,
and the genetic similarities between species provide well-established
arguments for macroevolution. Other elements of macroevolution --- such
as the development of the first life, the mechanisms for increasing
biological complexity and the origins of novel biological features ---
are weaker. In these areas, scientists have many speculative hypotheses
and comparatively less empirical data. It is simply a matter of
scientific honesty to admit this.
6. The Statement comes perilously close to contradicting itself when it
says in paragraph 18, "Science is not teleological: the accepted
processes do not start with a conclusion, then refuse to change it, or
acknowledge as valid only those data that support an unyielding
conclusion;" while saying in paragraph 5, "The diversity of life on
earth *is* the outcome of evolution: an unsupervised, impersonal,
unpredictable and natural process of temporal descent with genetic
modification that is affected by natural selection, chance, historical
contingencies and changing environments." Paragraph 5 sounds rather
like it is "starting with a conclusion."
The "scientific method" is actually a complicated mixture of finding
data to support a conclusion on one hand, and modifying conclusions in
the face of data on the other. While a great deal of young-earth
creationist literature is guilty of "bas[ing] theories on an untestable
collection of dogmatic proposals," the same could unfortunately be said
for some popular books on evolution. In view of this, a slight re-
wording of paragraph 18 would seem in order.
7. Paragraph 3 of the Statement says, "Explanations employing
nonnaturalistic or supernatural events, whether or not explicit
reference is made to a supernatural being, are outside the realm of
science and not part of a valid science curriculum." This seems overly
dogmatic. Explanations which include nonnaturalistic elements *can* be
scientifically appropriate, and can be part of a scientific curriculum,
if handled in a limited and careful fashion.
While science cannot study supernatural events, it can determine if a
"surprising" event occurred --- one for which no naturalistic
explanation is available. An obvious example of this is the "Big Bang."
Scientists have concluded that the Big Bang did occur. They can
determine what naturalistic events happened after the Big Bang.
However, science is (at present) incapable of saying whether the cause
of the Big Bang was supernatural, or some completely unknown
The example of the Big Bang can give us some ideas on how to handle
possible nonnaturalistic explanations for other historical events which
still lack a thorough "naturalistic" explanation (for example, the
origin of first life). In the case of the Big Bang, a science teacher
would first explain all the relevant scientific data, mechanisms, and
theories for what happened "after the Big Bang." At the end of this
discussion, the public school science teacher should be able to mention,
without favoring one or the other, the two common hypotheses for what
caused the Big Bang (supernatural event, or unknown naturalistic
When discussing the origins of first life or the first appearance of new
levels of biological complexity, the science teacher should first
explain the conditions leading up to the event, conditions after the
event, and whatever natural mechanisms are known about the event. The
teacher should also explain the best modern speculations for how these
events could have occurred naturalistically. Most biologists do believe
that evolutionary mechanisms will eventually be found to explain these
events in an empirical fashion, and it is appropriate to say so in
class. But it is also true that there are some people, including some
scientists, who are not convinced by these "best modern speculations."
Again, it is appropriate to say so in class. If handled in this careful
fashion, it would seem possible to mention, without advocating, that
these people prefer a "nonnaturalistic" explanation.
8. Young earth creationists form a very small minority of professional
scientists, but their views represent a sizable fraction of the
population, as shown by the numerous battles fought for its inclusion in
the curriculum. We would like to offer a suggestion on how to handle
this controversy which we hope is scientifically and educationally
credible, satisfactory to most people on all sides of the issue, and
compatible with church/state separation.
Young-earth models of astronomy, geology, and biology do not warrant
"equal billing" with the standard models. They do, however, have some
literature which presents those models separated from religious content,
so that the models can be evaluated on scientific merit. In school
districts where there is sufficient interest, the teacher could offer a
short, optional reading unit which makes available to students the
literature of both young-earth creationists and their critics. It
should not be a waste of time to let students learn how to evaluate
competing scientific models. This unit could be one of several short
reading units offered to students, from which students could choose, so
that participation would be entirely optional.
Below is a copy of your 1995 Statement on Teaching Evolution. We have
included specific suggestions for you to consider for future revisions,
which we believe will help in the goal of teaching evolution in an
effective, scientifically honest, and religiously neutral fashion.
> National Association of Biology Teachers (NABT)
> STATEMENT ON TEACHING EVOLUTION
> [Adopted by the Board of Directors, March 15, 1995.]
> As stated in The American Biology Teacher by the eminent
> scientist Theodosius Dobzhansky (1973), "Nothing in biology makes
> sense except in the light of evolution." This often-quoted
> assertion accurately illuminates the central, unifying role of
> evolution in nature, and therefore in biology.
As stated in The American Biology Teacher by the eminent
scientist Theodosius Dobzhansky (1973), "Nothing in biology makes
sense except in the light of evolution." This often-quoted
assertion accurately illuminates the importance of teaching evolution.
> Teaching biology in an effective and scientifically-honest manner
> requires classroom discussions and laboratory experiences on
> evolution. Modern biologists constantly study, ponder and
> deliberate the patterns, mechanisms and pace of evolution, but
> they do not debate evolution's occurrence.
but very few debate evolution's occurrence.
> The fossil record and
> the diversity of extant organisms, combined with modern
> techniques of molecular biology, taxonomy and geology, provide
> exhaustive examples and powerful evidence for genetic variation,
> natural selection, speciation, extinction and other
> well-established components of current evolutionary theory.
> Scientific deliberations and modifications of these components
> clearly demonstrate the vitality and scientific integrity of
> evolution and the theory that explains it.
> This same examination, pondering and possible revision have
> firmly established evolution as an important natural process
> explained by valid scientific principles, and clearly
> differentiate and separate science from various kinds of
> nonscientific ways of knowing, including those with a
> supernatural basis such as creationism. Whether called "creation
> science," "scientific creationism," "intelligent-design theory,"
> "young-earth theory" or some other synonym, creation beliefs have
> no place in the science classroom. Explanations employing
> nonnaturalistic or supernatural events, whether or not explicit
> reference is made to a supernatural being, are outside the realm
> of science and not part of a valid science curriculum.
> Evolutionary theory, indeed all of science, is necessarily silent
> on religion and neither refutes nor supports the existence of a
> deity or deities.
This same examination, pondering and possible revision firmly establish
evolution as an important natural process explained by valid scientific
principles, and differentiate the theory of evolution from other
theories of biological origins. "Young-earth creationism," by contrast,
starts from a religious basis. While some versions of "scientific
creationism" avoid explicit reference to supernatural events, they
invariably start with fixed conclusions which are not altered despite
the data. "Intelligent-design theory" --- while free from concerns
about the age of the earth --- employs philosophical arguments (for
example, the analogy between biological objects and man-made objects)
along with scientific arguments to make its claim. Explanations
employing nonnaturalistic or supernatural events, whether or not
explicit reference is made to a supernatural being, need to be handled
very carefully in the science classroom. Science education should
primarily be concerned with a thorough understanding of known
evolutionary mechanisms and data. If, at the end, philosophical or
religious questions are raised and discussed, they should be clearly
labeled as such, and consideration should be given to several competing
points of view. Evolutionary theory, indeed all of science, is
necessarily silent on religion and neither refutes nor supports the
existence of a deity or deities.
> Accordingly, the National Association of Biology Teachers, an
> organization of science teachers, endorses the following tenets
> of science, evolution and biology education:
> *The diversity of life on earth is the outcome of evolution: an
> unsupervised, impersonal, unpredictable and natural process of
> temporal descent with genetic modification that is affected by
> natural selection, chance, historical contingencies and changing
*Evolution is a natural process of temporal descent with genetic
modification that is affected by natural selection, chance, historical
contingencies and changing environments. The theory of evolution seeks
to explain the diversity of life on earth through common descent and
> *Evolutionary theory is significant in biology, among other
> reasons, for its unifying properties and predictive features, the
> clear empirical testability of its integral models and the
> richness of new scientific research it fosters.
> *The fossil record, which includes abundant transitional forms in
> diverse taxonomic groups, establishes extensive and comprehensive
> evidence for organic evolution.
*The fossil record shows that earlier members of related taxonomic
groups were closer to each other than later members of those same
groups. There are numerous transitional forms in many different
taxonomic groups, as well as long periods with relatively little change
in many taxonomic groups. This is consistent with the modern
understanding of evolution.
*The word "evolution" takes on several meanings in biology. (1) The
mechanisms of evolution (such as mutation, recombination, and natural
selection) can be clearly observed and measured, in nature and in the
laboratory. (2) The phenomenon of genetic change over time is observed
in modern-day populations of plants and animals. This is sometimes
called "microevolution." (3) The overall theory of evolution seeks to
explain the history and diversity of life by common descent and
modification through evolutionary mechanisms. This is an extrapolation
of microevolution to all of biological history. (4) The fossil record,
genetic and developmental similarities between diverse species, and the
phenomenon of microevolution provide data to support and constrain the
overall theory of evolution. Each of these categories of "evolution"
must be taught, along with their inter-relationships. It is also
important for students to learn to distinguish between the different
> *Natural selection, the primary mechanism for evolutionary
> changes, can be demonstrated with numerous, convincing examples,
> both extant and extinct.
> *Natural selection--a differential, greater survival and
> reproduction of some genetic variants within a population under
> an existing environmental state--has no specific direction or
> goal, including survival of a species.
> *Adaptations do not always provide an obvious selective
> advantage. Furthermore, there is no indication that
> adaptations--molecular to organismal--must be perfect:
> adaptations providing a selective advantage must
> simply be good enough for survival and increased reproductive
> *The model of punctuated equilibrium provides another account of
> the tempo of speciation in the fossil record of many lineages: it
> does not refute or overturn evolutionary theory, but instead adds
> to its scientific richness.
> *Evolution does not violate the second law of thermodynamics:
> producing order from disorder is possible with the addition of
> energy, such as from the sun.
> *Although comprehending deep time is difficult, the earth is
> about 4.5 billion years old. Homo sapiens has occupied only a
> minuscule moment of that immense duration of time.
> *When compared with earlier periods, the Cambrian explosion
> evident in the fossil record reflects at least three phenomena:
> the evolution of animals with readily-fossilized hard body parts;
> Cambrian environment (sedimentary rock) more conducive to
> preserving fossils; and the evolution from pre-Cambrian forms of
> an increased diversity of body patterns in animals.
*When compared with earlier periods, the Cambrian explosion
evident in the fossil record reflects at least three phenomena:
the evolution of animals with readily-fossilized hard body parts;
Cambrian environment (sedimentary rock) more conducive to
preserving fossils; and the evolution from pre-Cambrian forms of
an increased diversity of body patterns in animals. Even so, the
Cambrian explosion is a remarkable period in biological history which
requires further scientific investigation.
> *Radiometric and other dating techniques, when used properly, are
> highly accurate means of establishing dates in the history of the
> planet and in the history of life.
> *In science, a theory is not a guess or an approximation but an
> extensive explanation developed from well-documented,
> reproducible sets of experimentally-derived data from repeated
> observations of natural processes.
> *The models and the subsequent outcomes of a scientific theory
> are not decided in advance, but can be, and often are, modified
> and improved as new empirical evidence is uncovered. Thus,
> science is a constantly self-correcting endeavor to understand
> nature and natural phenomena.
*As with any scientific theory which seeks to explain such a broad range
of phenomena, some parts of evolution are well-established by
reproducible sets of data, while other parts are more speculative
extrapolations from known natural processes. Many well-established
facts of evolution are mentioned in preceding paragraphs. In other
parts of evolutionary theory, such as the origin of first life and the
developments of increased biological complexity, there is less empirical
data and greater inference. In these areas, there needs to be, and is
ongoing, more scientific research to learn the details about how they
> *Science is not teleological: the accepted processes do not start
> with a conclusion, then refuse to change it, or acknowledge as
> valid only those data that support an unyielding conclusion.
> Science does not base theories on an untestable collection of
> dogmatic proposals. Instead, the processes of science are
> characterized by asking questions, proposing hypotheses, and
> designing empirical models and conceptual frameworks for research
> about natural events.
*Science does not start with a conclusion, then refuse to change it, or
acknowledge as valid only those data that support an unyielding
conclusion. Instead, the processes of science are characterized by
asking questions, proposing hypotheses, and designing empirical models
and conceptual frameworks for research about natural events.
> *Providing a rational, coherent and scientific account of the
> taxonomic history and diversity of organisms requires inclusion
> of the mechanisms and principles of evolution.
> *Similarly, effective teaching of cellular and molecular biology
> requires inclusion of evolution.
> *Specific textbook chapters on evolution should be included in
> biology curricula, and evolution should be a recurrent theme
> throughout biology textbooks and courses.
> *Students can maintain their religious beliefs and learn the
> scientific foundations of evolution.
> *Teachers should respect diverse beliefs, but contrasting science
> with religion, such as belief in creationism, is not a role of
> science. Science teachers can, and often do, hold devout
> religious beliefs, accept evolution as a valid scientific theory,
> and teach the theory's mechanisms and principles.
> *Science and religion differ in significant ways that make it
> inappropriate to teach any of the different religious beliefs in
> the science classroom.
*Teachers should take care to avoid teaching certain religious and
philosophical claims which are sometimes appended to evolution in the
popular literature. Statements that God is "unnecessary" if evolution
is true, that human existence happened purely by chance, and that there
is no such thing as universal moral truths, are statements that go
beyond science, and should not be taught as a necessary "consequence" of
*Some teachers will wish to avoid all discussion of philosophical or
religious questions, but this may prove difficult if evolution is
discussed for any length of time. It is likely, and natural, that
certain kinds of questions will be asked: Could God have directed
evolution? Could God have intervened to create the first life or at
other times in history? Could it all have happened without God? Did
humans appear only by chance? Does biology show "intelligent design"?
Does evolution mean that there's no such thing as right and wrong? If
and when these questions are discussed, it should be clear to the
students that these are philosophical and religious questions which go
beyond science. Scientists have different opinions about these
questions and can still agree about the scientific matters of evolution.
> Opposition to teaching evolution reflects confusion about the
> nature and processes of science. Teachers can, and should, stand
> firm and teach good science with the acknowledged support of the
> courts. In Epperson v. Arkansas (1968), the U.S. Supreme Court
> struck down a 1928 Arkansas law prohibiting the teaching of
> evolution in state schools. In McLean v. Arkansas (1982), the
> federal district court invalidated a state statute requiring
> equal classroom time for evolution and creationism.
> Edwards v. Aguillard (1987) led to another Supreme Court ruling
> against so-called "balanced treatment" of creation science and
> evolution in public schools. In this landmark case, the Court
> called the Louisiana equal-time statute "facially invalid as
> violative of the Establishment Clause of the First Amendment,
> because it lacks a clear secular purpose." This decision--"the
> Edwards Restriction"--is now the controlling legal position on
> attempts to mandate the teaching of creationism: the nation's
> highest court has said that such mandates are unconstitutional.
> Subsequent district court decisions in Illinois and California
> have applied "the Edwards restriction" to teachers who advocate
> creation science, and to the right of a district to prohibit an
> individual teacher from promoting creation science, in the
*If teachers desire to include some creation science material in the
science curriculum, it should be optional for the students (due to its
inherently religious basis), limited in scope, and balanced with
critical material. For example, a joint evaluation of creation science
material and critical material could be one of several short, optional
reading units offered to students.
> Courts have thus restricted school districts from requiring
> creation science in the science curriculum and have restricted
> individual instructors from teaching it. All teachers and
> administrators should be mindful of these court cases,
> remembering that the law, science and NABT support them as they
> appropriately include the teaching of evolution in the science
> References and Suggested Reading:
> Clough, M. (1994). Diminish students' resistance to biological
> evolution. The American Biology Teacher, 56, pp. 409-415.
> Futuyma, D. (1986). Evolutionary Biology, 2nd ed. Sunderland, MA:
> Sinauer Associates, Inc.
> Gillis, A. (1994). Keeping creationism out of the classroom.
> Bioscience, 44, pp. 650-656.
> Gould, S. (1977). Ever since Darwin: Reflections in natural
> history. NY: W.W. Norton & Co.
> Gould, S. (1994), October). The evolution of life on earth.
> Scientific American, 271, pp. 85-91.
> Mayr, E. (1991). One long argument: Charles Darwin and the
> Genesis of modern evolutionary thought. Cambridge, MA: Harvard
> University Press.
> McComas, W. (Ed.). (1994). Investigating evolutionary biology in
> the laboratory. Reston, VA: NABT.
> Moore, J. (1993). Science as a way of knowing--The foundations of
> modern biology. Cambridge, MA: Harvard University Press.
> National Center for Science Education. P.O. Box 9477, Berkeley,
> CA 94709. Numerous publications such as Facts, faith and
> fairness--Scientific creationism clouds scientific literacy by S.
> Walsh and T. Demere.
> Numbers, R. (1992). The creationists: The evolution of scientific
> creationism. Berkeley, CA: University of California Press.
> Weiner, J. (1994). Beak of the Finch--A Story of evolution in our
> time. NY: Alfred A. Knopf.
Dr. Loren Haarsma