Download evolutio - The Skeptic Tank

By: Shelby Sherman
To: Tyler A. Wunder
Re: Theory of evolution
TAW>
Would someone "in-the-know" kindly lay out an evolutionary
theory or
TAW> two so Bill Wolff will provide us with his theory of creationism,
or at
TAW> least be unable to honestly gainsay the request for his theory?
AN INTRODUCTION TO EVOLUTIONARY BIOLOGY -- BY CHRIS COLBY
*********************************************************
INTRODUCTION
-----------Evolution is one of the most powerful theories science has ever known.
For a variety of reasons, however, it is also one of the most
misunderstood. One common misunderstanding is that the phrase "survival
of the fittest" summarizes evolutionary theory. In fact, it does not.
The phrase is both incomplete and misleading. Two other common
misinterpretations are that evolution is progress and organisms can be
arranged on an evolutionary ladder from bacteria to man.
This post is an outline of the basics of evolutionary biology. It is
intended to be a brief overview of the concepts and mechanisms of
evolution. Creationist arguments are not addressed directly here; nor
is a "laundry list" of reasons to believe in evolution provided. Many
interesting topics in evolutionary biology are not covered (symbiosis
and endosymbiosis, origins of life, evolution of sex, human evolution
and much more) because I can't include everything and keep this down
to a readable length.
WHAT IS EVOLUTION?
Evolution is a change in the gene pool of a population over time. The
gene pool is the set of all genes of a species or population. The
English moth, _Biston__betularia_, is a frequently cited example of
observed evolution. In this moth, rare black variants spread through
the population as a result of their habitat becoming darkened by soot
from factories. Birds could see the lighter colored moths more readily
and ate more of them. The moth population changed from mostly light
colored moths to mostly dark colored moths. Since their color was
determined by a single gene, the change in frequency of dark colored
moths represented a change in the gene pool. This change was, by
definition, evolution.
The kind of evolution documented above is called "microevolution".
Larger changes (taking more time) are termed "macroevolution". Some
biologists feel the mechanisms of macroevolution are different from
those of microevolutionary change. Others, including myself, feel the
distinction between the two is arbitrary. Macroevolution is cumulative
microevolution.
In any case, evolution is defined as a change in the gene pool. This
means that evolution is a population level phenomena. Only groups
of organisms evolve. An individual organism does not evolve, nor
do subunits of organisms evolve (with limited exceptions). So, when
thinking of evolution, is neccessary to view populations as a collection
of individuals.
I have defined evolution, here, as a process and that is how I will
use the term in this essay. Keep in mind, however, that in everyday use
evolution often refers to a variety of things. The fact that all
organisms are linked via descent to a common ancestor is often called
evolution. The theory that life arose solely via natural processes is
often called evolution (instead of abiogenesis). And frequently, people
use the word evolution when they really mean natural selection -- one
of the many mechanisms of evolution.
WHAT ISN'T EVOLUTION?
For many people evolution is equated with morphological change, i.e.
organisms changing shape or size over time. An example would be a
dinosaur species slowly turning into a bird species. It is important
to note that evolution is often accompanied by morphological change,
but this need not be the case. Evolution can occur without
morphological change; and morphological change can occur without
evolution. For instance, humans are larger now than in the past few
hundred years, but this is not an evolutionary change. Better diet and
medicine brought about this change, so it is not an example of
evolution. The gene pool did not change -- only its manifestation did.
An organism's phenotype is determined by both its genes and its
environment. Phenotype means the morphological, physiological, biochemical, behavioral and other properties exhibited by a living
organism. Phenotypic changes induced solely by changes in
environment do not count as evolution because this change is not
heritable. In other words the change is not passed on to the organism's
offspring. Most changes due to environment are fairly subtle (e.g. size
differences). Large scale phenotypic changes (such as dinosaur to
bird) are obviously due to genetic changes, and therefore are
evolution.
WHAT EVOLUTION ISN'T
Evolution is not progress. Organisms simply adapt to their current
surroundings and do not necessarily become "better" over time. A
trait or strategy that is successful for an organism at one time may be
deleterious at another. Studies in yeast have shown that "more evolved"
strains of yeast can sometimes be competitively inferior to "less
evolved" strains. An organism's success or failure depends to a great
deal on the behavior of its contemporaries; for most traits or
behaviors there is likely no optimal design or strategy, only
contingent designs or strategies.
HOW DOES EVOLUTION WORK?
If evolution is a change in the gene pool; what causes the gene pool to
change? Several mechanisms can bring about a change in the gene pool,
among them: natural selection, genetic drift, gene flow, mutation and
recombination. I will discuss these in more detail later. It is
important to understand the difference between evolution (change in the
gene pool) and the mechanisms that bring about this change.
GENETIC VARIATION
----------------Bringing about a change in the gene pool assumes that there is genetic
variation in the population to begin with, or a way to generate it.
Genetic variation is "grist for the evolutionary mill". For example, if
there were no dark moths, the population could not have evolved from
mostly light to mostly dark. In order for continuing evolution there
must be mechanisms to both increase genetic variation, or create it,
(e.g. mutation) and decrease variation (e.g. natural selection and
genetic drift).
HOW IS GENETIC VARIATION DESCRIBED?
Genetic variation has two components: allelic diversity and non-random
associations of alleles. Alleles are different versions of the same
gene at a given locus. For example, at the blood group locus (locus means
location) humans can have an A, B or O allele. There are subtypes of
these alleles as well. Most animals, including humans, are
diploid. This means they contain two alleles for every gene at every
locus. If the two alleles are the same type (for instance two A
alleles) the individual would be termed "homozygous" for that locus. An
individual with two different alleles at a locus is called
"heterozygous".
Allelic diversity is simply the number of alleles at each locus scaled
by their frequency in the gene pool. At any given locus there can be
many different alleles in the gene pool. It is important to realize
that there can be more alleles in the gene pool at any locus than
any single organism can possess.
Linkage disequilibrium is a measure of association of alleles at
different loci. If each gene assorted entirely independently, the gene
pool would be at linkage equilibrium. However, if some alleles were
often
found together in organisms (ie. did not assort randomly) these alleles
would be in linkage disequilibrium. Linkage disequilibrium can be the
result of physical proximity of the genes or maintained by natural
selection if some combinations of alleles work better as a team.
WHAT IS EVOLUTION?
version 2, January 22, 1993
Most non-scientists seem to be quite confused about precise definitions
of
biological evolution. Such confusion is due in large part to the
inability of
scientists to communicate effectively to the general public and also to
confusion among scientists themselves about how to define such an
important term. When discussing evolution it is important to distinguish
between the existence of evolution and various theories about the
mechanism
of evolution. And when referring to the existence of evolution it is
important
to have a clear definition in mind. What, exactly, do biologist mean when
they
say that they have observed evolution or that humans and chimps have
evolved
from a common ancestor.
One of the most respected evolutionary biologists has defined biological
evolution as follows,
"In the broadest sense, evolution is merely change, and so is
all-pervasive; galaxies, languages, and political systems all
evolve. Biological evolution ... is change in the properties
of populations of organisms that transend the lifetime of a
single individual. The ontogeny of an individual is not considered
evolution; individual organisms do not evolve. The changes in
populations that are considered evolutionary are those that are
inheritable via the genetic material from one generation to the
next. Biological evolution may be slight or substantial; it
embraces
everything from slight changes in the proportion of different
alleles within a population (such as those determining blood
types) to the successive alterations that led from the earliest
protoorganism to snails, bees, giraffes, and dandelions."
Douglas J. Futuyma in Evolutionary Biology, Sinauer Associates 1986
It is important to note that biological evolution refers to populations
and
not to individuals and that the changes must be passed on to the next
generation. In practice this means that,
Evolution is a process that results in heritable changes in a
population spread over many generations
This is a good working scientific definition of evolution; one that can
be
used to distinguish between evolution and similar changes that are not
evolution. Another common short definition of evolution can be found in
many textbooks,
"In fact, evolution can be precisely defined as any change in the
frequency of alleles within a gene pool from one generation to
the next."
Helena Curtis and N. Sue Barnes BIOLOGY 5th ed. 1989
Worth Publishers, p.974
One can quibble about the accuracy of such a definition (and we have
often
quibbled on these newsgroups) but it also conveys the essence of what
evolution really is. When biologists say that they have observed
evolution
they mean that they have detected a change in the frequency of genes in a
population. (Often the genetic change is inferred from phenotypic changes
that
are heritable.) When biologists say that humans and chimps have evolved
from
a common ancestor they mean that there have been successive heritable
changes
in the two separated populations since they became isolated.
Unfortunately the common definitions of evolution outside of the
scientific
community are different. For example, in the Oxford Concise Science
Dictionary
we find the following definition;
"evolution: The gradual process by which the present diversity
of plant and animal life arose from the earliest and most primitive
organisms, which is believed to have been continuing for the
past 3000 million years."
This is inexcusable for a dictionary of science. Not only does this
definition
exclude prokaryotes, protozoa, and fungi, but it specifically includes a
term
"gradual process" which should not be part of the definition. More
importantly
the definition seems to refer more to the history of evolution than to
evolution itself. Using this definition it is possible to debate whether
evolution is still occurring but the definition provides no easy way of
distinguishing evolution from other processes. For example, is the
increase
in height among Caucasians over the past several hundred years an example
of
evolution? Are the color changes in the peppered moth population examples
of evolution? This is not a scientific definition.
Standard dictionaries are even worse.
"evolution: ...the doctrine according to which higher forms of
life have gradually arisen out of lower.."
Chambers
"evolution: ...the development of a species, organsim, or organ
from its original or primitive state to its present or
specialized state; phylogeny or ontogeny: Webster's
These definitions are simply wrong. Unfortunately it is common for nonscientists to enter into a discussion about evolution with such a
definition
in mind. This often leads to fruitless debate since the experts are
thinking
about evolution from a different perspective. When someone claims that
they
don't believe in evolution they cannot be referring to an acceptable
scientific definition of evolution because that would be denying
something
which is easy to demonstrate. It would be like saying that they don't
believe
in gravity!
Recently I read a statement from a creationist who claimed that
scientists
are being dishonest when they talk about evolution. This person believed
that
evolution was being misrepresented to the public. The real problem is
that
the public, and creationists, do not understand what evolution is all
about.
This person's definition of evolution was very different from the common
scientific definition and as a consequence he was unable to understand
what evolutionary biology really meant. This is the same person who
claimed
that one could not "believe" in evolution and still be religious! But
once
we realize that evolution is simply "a process that results in heritable
changes in a population spread over many generations" it seems a little
silly
to pretend that this excludes religion!
Scientists such as myself, must share the blame for the lack of public
understanding of science. We need to work harder to convey the correct
information. Sometimes we don't succeed very well but that does not mean
that
we are dishonest. On the other hand, the general public, and creationists
in particular, need to also work a little harder in order to understand
science. Reading a textbook would help.
Laurence A. Moran (Larry)
==* MORAN EVOLUTION FACT_AND_THEORY REFS
EVOLUTION AS A FACT AND A THEORY
version 2.1 (January 22, 1993)
When non-biologists talk about biological evolution they often confuse
two different aspects of the definition. On the one hand there is the
question of whether or not modern organisms have evolved from older
ancestral organisms or whether modern species are continuing to change
over time. On the other hand there are questions about the mechanism of
the observed changes... how did evolution occur? Biologists consider
the existence of biological evolution to be a FACT. It can be
demonstrated
today and the historical evidence for it's occurrence in the past is
overwhelming. However, biologists readily admit that they are less
certain of the exact MECHANISM of evolution; there are several THEORIES
of the mechanism of evolution.
Stephan J. Gould has put this as well as anyone else,
"In the American vernacular, "theory" often means "imperfect
fact" - part of a hierarchy of confidence running downhill
from fact to theory to hypothesis to guess. Thus the power
of the creationist argument: evolution is "only" a theory
and intense debate now rages about many aspects of the theory.
If evolution is worse than a fact, and scientists can't even
make up their minds about the theory, then what confidence can
we have in it? Indeed, President Reagan echoed this argument
before an evangelical group in Dallas when he said (in what
I devoutly hope was campaign rhetoric): 'Well, it is a theory.
It is a scientific theory only, and it has in recent years
been challenged in the world of science - that is, not believed
in the scientific community to be as infallible as it once was.'
Well evolution is a theory. It is also a fact. And facts and
theories are different things, not rungs in a hierarchy of
increasing certainty. Facts are the world's data. Theories
are structures of ideas that explain and interpret facts.
Facts don't go away when scientists debate rival theories to
explain them. Einstein's theory of gravitation replaced Newton's
in this century, but apples didn't suspend themselves in midair,
pending the outcome. And humans evolved from ape-like ancestors
whether they did so by Darwin's proposed mechanism or by some
other yet to be discovered.
Moreover, 'fact' doesn't mean 'absolute certainty'; there ain't
no such animal in an exciting and complex world. The final proofs
of logic and mathematics flow deductively from stated premises and
achieve certainty only because they are NOT about the empirical
world. Evolutionists make no claim for perpetual truth, though
creationists often do (and then attack us falsely for a style of
argument that they themselves favor). In science 'fact' can only
mean 'confirmed to such a degree that it would be perverse to
withhold provisional consent'. I suppose that apples might start
to rise tomorrow, but the possibility does not merit equal time in
physics classrooms.
Evolutionists have been very clear about this distinction of fact
and theory from the very beginning, if only because we have always
acknowledged how far we are from completely understanding the
mechanisms (theory) by which evolution (fact) occurred. Darwin
continually emphasized the difference between his two great and
separate accomplishments: establishing the fact of evolution, and
proposing a theory - natural selection - to explain the mechanism
of evolution."
Stephen J. Gould "Evolution as Fact and Theory"; Discover, May 1981
Gould is stating the prevailing view of the scientific community. In
other words, the experts on evolution consider it to be a FACT. This
is not an idea that originated with Gould as the following quotations
indicate;
"Let me try to make crystal clear what is established beyond
reasonable doubt, and what needs further study, about evolution.
Evolution as a process that has always gone on in the history of
the earth can be doubted only by those who are ignorant of the
evidence or are resistant to evidence, owing to emotional blocks
or to plain bigotry. By contrast, the mechanisms that bring
evolution about certainly need study and clarification. There
are no alterantives to evolution as history that can withstand
critical examination. Yet we are constantly learning new and
important facts about evolutionary mechanisms."
Theodosius Dobzhansky "Nothing in Biology Makes Sense Except in
the Light of Evolution", American Biology Teacher vol.35 (March
1973) reprinted in EVOLUTION VERSUS CREATIONISM, J. Peter
Zetterberg ed., ORYX Press, Phoenix AZ 1983
----------------------------------------------"It is time for students of the evolutionary process, especially
those who have been misquoted and used by the creationists, to
state clearly that evolution is a FACT, not theory, and that what
is at issue within bology are questions of details of the process
and the relative importance of different mechanisms of evolution.
It is a FACT that the earth with liquid water, is more than 3.6
billion years old. It is a FACT that cellular life has been around
for at least half of that period and that organized multicellular
life is at least 800 million years old. It is a FACT that major
life forms now on earth were not at all represented in the past.
There were no birds or mammals 250 million years ago. It is a FACT
that major life forms of the past are no longer living. There used
to be dinosaurs and Pithecanthropus, and there are none now. It is
a FACT that all living forms come from previous living forms.
Therefore, all present forms of life arose from ancestral forms that
were different. Birds arose from nonbirds and humans from nonhumans.
No person who pretends to any understanding of the natural world
can deny these facts any more than she or he can deny that the
earth is round, rotates on its axis, and revolves around the sun.
The controversies about evolution lie in the realm of the
relative importance of various forces in molding evolution."
R. C. Lewontin "Evolution/Creation Debate: A Time for Truth"
Bioscience 31, 559 (1981) reprinted in EVOLUTION VERSUS CREATIONISM
op cit.
There are readers of these newsgroups who reject evolution for religious
reasons. In general these readers oppose both the FACT of evolution and
THEORIES of mechanisms although some anti-evolutionists have come to
realize that there is a difference between the two concepts. That is
why we see some leading anti-evolutionists admitting to the fact of
"microevolution" - they know that evolution can be demonstrated. These
readers will not be convinced of the "facthood" of (macro)evolution by
any logical argument and it is a waste of time to make the attempt. The
best that we can hope for is that they understand the argument that
they oppose. Even this simple hope is rarely fulfilled.
There are some readers who are not anti-evolutionist but still claim
that evolution is "only" a theory which can't be proven. This group
needs to distinguish between the fact that evolution occurs and the
theory of the mechanism of evolution.
We also need to distinguish between facts that are easy to demonstrate
and those that are more circumstantial. Examples of evolution that are
readily apparent include the fact that modern populations are evolving
and the fact that two closely related species share a common ancestor.
The evidence that Homo sapiens and chimpanzees share a recent common
ancestor falls into this catagory. There is so much evidence in support
of this aspect of primate evolution that it qualifies as a fact by any
common definition of the word "fact".
In other cases the available evidence is less strong. For example, the
relationships of some of the major phyla are still being worked out.
Also, the statement that all organisms have descended from a single
common ancestor is strongly supported by the available evidence, and
there is no opposing evidence. However, it is not yet appropriate to
call this a "fact" since there are reasonable alternatives.
Finally, there is an epistemological argument against evolution as fact.
Some readers of these newsgroups point out that nothing in science can
ever be "proven" and this includes evolution. According to this argument,
the probability that evolution is the correct explanation of life as we
know it may approach 99.9999...9% but it will never be 100%. Thus
evolution cannot be a fact. This kind of argument might be appropriate
in a philosophy class (it is essentially correct) but it won't do in
the real world. A "fact", as Stephen J. Gould pointed out (see above),
means something that is so highly probable that it would be silly not
to accept it. This point has also been made by others who contest the
nit-picking epistemologists.
"The honest scientist, like the philosopher, will tell you that
nothing whatever can be or has been proved with fully 100%
certainty, not even that you or I exist, nor anyone except himself,
since he might be dreaming the whole thing. Thus there is no sharp
line between speculation, hypothesis, theory, principle, and fact,
but only a difference along a sliding scale, in the degree of
probability of the idea. When we say a thing is a fact, then, we
only mean that its probability is an extremely high one: so high
that we are not bothered by doubt about it and are ready to act
accordingly. Now in this use of the term fact, the only proper one,
evolution is a fact. For the evidence in favor of it is as
voluminous,
diverse, and convincing as in the case of any other well established
fact of science concerning the existence of things that cannot be
directly seen, such as atoms, neutrons, or solar gravitation ....
So enormous, ramifying, and consistant has the evidence for
evolution become that if anyone could now disprove it, I should
have my conception of the orderliness of the universe so shaken
as to lead me to doubt even my own existence. If you like, then,
I will grant you that in an absolute sense evolution is not a fact,
or rather, that it is no more a fact than that you are hearing or
reading these words."
H. J. Muller, "One Hundred Years Without Darwin Are Enough"
School Science and Mathematics 59, 304-305. (1959) reprinted
in EVOLUTION VERSUS CREATIONISM op cit.
In any meaningful sense evolution is a fact but there are various
theories concerning the mechanism of evolution.
-Brett J. Vickers
[email protected]
"Don't go around saying the world owes you
a living. The world owes you nothing.
It was here first." - Mark Twain
I was asked by somebody in another echo to post this article in here. It
was
written by Ranse Traxler, the Executive Director of the St. Louis
Association
for the Teaching of Evolution (SLATE) and originally published in The
American
Rationalist. The REALL News (official newsletter of the Rational
Examination
Association of Lincoln Land) reprinted the article with permission in its
third
issue. If anybody wishes to reprint this article further, you must get
the
permission of The American Rationalist (see end of article for address).
The
REALL News issue may be FReq'ed from 2430/2112 as REALL1-3.ZIP. Issues 2
and 4
are also available.
=========================================================================
The Misconceptions of Evolution
By Ransom R. Traxler
In spite of our technical society and our public school
system, most people believe in many misconceptions about
evolution. This is due, in part, to educators who wish to
avoid controversy or who do not fully understand the subject
they teach. Furthermore, anti-evolutionists knowingly
propagate these erroneous beliefs in their religious crusade
against science. As a systematic biologist (in whose field
organic evolution begins), I wish to correct a few of these
myths. These statements are not just personal beliefs--they
are facts and concepts supported by volumes of research and
agreed upon by those scientists who are most knowledgeable
about the subject.
_Evolution is just a theory._ Evolution is a valid
scientific theory, just like electricity, gravity, atoms,
light, cells, and disease-causing germs are valid scientific
theories also. For example, we are taught that the earth
orbits the sun; scientists call this the heliocentric
theory. A theory in science is a highly-tested, verified
and demonstrated explanation for observed facts, not "a
guess or conjecture." To state that evolution is only a
theory is the same as stating that gravity is only a theory.
Knowing this, who would still wish to contest it by jumping
off a building?
_Evolution is not based on facts._ There are facts and
theories about evolution. The facts of evolution are that
the earth is billions of years old and that the life on it
has changed over that time. The fossil record is clear that
life living today differs greatly from that living, say, 300
million years ago. In between we have a vast collection of
fossils that, as one looks at younger and younger specimens,
become more modern-looking. The theories of evolution are
about what caused this metamorphosis. We know several
mechanisms that can produce changes in organisms: natural
selection, genetic drift, the founder effect, genetic
recombination and mutations are just a few. The debates
scientists have are about the mechanism of evolution, not
the fact that it has occurred. Practicing scientists do not
doubt evolution.
_Darwin invented evolution._ Would one say that Newton
invented gravity or Einstein invented time? The evidence
for evolution had been known by scientists for centuries.
In the sixteenth, seventeenth and eighteenth centuries the
early naturalists, who were also clergy, discovered that the
earth was very old and that life was very different in the
past. However, evolution was not generally accepted because
no one knew how it was happening. In the nineteenth century
Darwin was the first to propose a valid mechanism to explain
what produced evolution. Since then his mechanism, natural
selection, has been thoroughly tested and was rapidly
accepted by scientists everywhere. Likewise, continental
drift was thought of since Benjamin Franklin's time, but it
was not until the 1960's that a valid mechanism, plate
tectonics, was discovered. Today scientists accept it as
they accept evolution. We now have several mechanisms that
explain how evolution occurs, discovered by many scientists
over the last century.
_Evolution is caused by blind chance._ In all aspects of
evolution (cosmic, chemical and organic) natural laws and
principles can explain what has occurred. These influences
act as a controlling force that guides evolution to
predictable outcomes. Cosmic evolution is governed by the
laws of physics, not chance. Gravity and nuclear reactions
cause the birth and death of stars and planets (we have
witnessed these events with telescopes). Chemical evolution
abides by the laws of molecular reactions which can produce
complicated organic molecules naturally (we have witnessed
this in the laboratory). Organic evolution is directed by
biological principles such as natural selection and
genetics, which again we have observed in the laboratory.
The odds are, at the moment of conception, over
70,000,000,000,000 (70 million million) to one that your
genes will not come together in the combination now in your
body. However, you are here and it was all controlled by
the principles of genetics. Natural forces and laws govern
and direct evolution, not "blind chance."
_Complex organisms, such as ourselves, must have been
designed by a more complex, intelligent creator._ This
argument has been shown to be logically and scientifically
false for at least a hundred years, yet it is still used by
anti-evolutionists in their religious crusade. Logically
for their argument to be true, two criteria must be adhered
to:
One: everything as complex as a living organism must
have been designed. No exceptions, or else we could be here
not by design but by the natural process of evolution.
Two: everything as complex as a living organism must
have a designer even more complex than it is. If this was
not true, then we could have been designed by a less complex
primate who, in turn was designed by a less complex mammal,
and on and on to a primordial cell. This is a teleologic
view of evolution.
Since the two conditions above must be true or the
design argument fails miserably then who designed our morecomplex-than-we-are-designer? And who, in turn, designed
him? These two conditions require an infinite number of
designers, each one more complex than the one he designed.
Scientifically, there is another choice instead of a
designer or blind chance; evolution, which is guided by the
laws and forces of nature. We have documented cases of
changes produced by natural selection, which acts as a
"designing force" to make organisms better suited to their
environment. However, it is not as perfect as an omnipotent
designer would be.
There are thousands of examples of poor design in
nature. Many organisms use modified organs that barely suit
their need; many organisms have vestigial parts that do not
help them but could actually harm (wisdom teeth and appendix
in us, hind limbs in whales and snakes, and much more). If
this is the work of a designer, then it was a terrible job.
We, with artificial selection (breeding) and genetic
changes, are improving on some of the poor designs of
nature.
_Creationism is another scientific explanation._ This is
definitely not true. Creationism is a religious belief
based on the Bible. Evolution is a scientific explanation
based on observation, experimentation and objective
evaluation. None of the vast store of scientific data we
have supports a literal interpretation of the Book of
Genesis. The small amount of "scientific" evidence
propagated by "scientific creationists" has been
investigated by the scientific community using the
scientific method (just like evolution has been for over 150
years). Most of these claims were abandoned by scientists
over two centuries ago because the data and experiments did
not support them. The newest claims were found to be
distortions and misrepresentations of firmly established
data. Creationism is a religious belief and, as such,
everyone is free to believe it or not; but as a scientific
explanation, it has no support whatsoever in fact.
_Creationism should be given equal time in the science
class because so many people believe in it._ Many people
believe in astrology; should it be given time in an
astronomy class? Or how about alchemy in a chemistry class?
Numerology in a mathematics class? Atlantis and ancient
astronauts in a history class? Flat-earth in a geography
class? If some people believe that 6x9=42, should we give
the students two multiplication tables and let them choose
which one they will use? The science classroom is not where
religious beliefs should be presented as fact for the
student to accept or reject as he/she wants. Instead, the
classroom is where the current knowledge in the field is
presented to students to increase their understanding of
that subject.
_Evolution should not be taught because it is
unimportant._ Evolution is to biology as atoms are to
chemistry. It is the unifying concept that connects
genetics, anatomy, medical science, taxonomy and many others
into a comprehensible framework. It is THE central idea of
biology that ties together all its subparts. Evolutionary
biology explains the distribution of life on this planet,
tissue rejection in transplants, and how our body works. In
other fields cosmic evolution is the center of astronomy (it
tells us how the universe and stars function) and earth
evolution is the basic concept of geology (it tells us how
the earth came to be as it is today).
What would chemistry be like without atoms to explain
how and why chemicals react as they do; or physics without
the concept of energy being able to convert into different
forms to explain how a steam engine works? What if a
teacher felt that atoms or energy were unimportant and
ignored them in his/her chemistry or physics class? Without
the why and how explained by evolution, much of science
becomes a meaningless collection of facts with no logical
association or understanding.
_Evolution should not be taught because it is contrary
to some people's religious beliefs._ First of all our
government is religiously neutral according to our
Constitution. Therefore, religion cannot be a factor in
determining the curriculum. Secondly, the teacher has the
obligation to present the students all the knowledge of the
subject being taught based on their level of understanding.
Any science teacher who fails to present evolution properly
to the students betrays the trust placed in them by the
public and acts in an unprofessional manner.
_Evolution should not be taught because it promotes the
religion of secular humanism._ Evolution is a science and
that is all it is. People are free to form whatever
philosophies or religions they want based on whatever source
they want. Some people have formed their belief system
around old books variously translated through the years.
Primitive people use a god or gods to explain ordinary
occurrences in nature because that is the only way they can
comprehend the world around them. Scientists of all
religions accept evolution because it is the best scientific
explanation we have not because of some religious reason.
As a religiously-neutral science, it should be taught in the
classroom.
_Evolution is anti-God._ Impossible, for science just
like mathematics is neutral towards any religious belief.
Science and religion are two separate philosophies dealing
with different realms. Religion deals with the supernatural
and cannot be supported by experimentation--it must be
accepted by faith alone. Science deals with the natural
universe and its discoveries can be confirmed or disproved
by experimentation--scientific ideas are accepted by the
scientific community based on evidence. Evolution, as any
science, can never say anything about the "Ultimate Cause"
of the universe and our existence; these can only be
answered by religion. Since these two philosophies deal
with different realms, there is no basic conflict between
them.
_Evolutionists are atheists._ Many scientists and
science teachers are devoutly Christian or Jewish. Some of
the great founders of evolutionary biology were strong
theists. A few of us are atheists. This is because we are
able to separate the two realms of our lives--the spiritual
and the material. Since evolution does not deny the
existence of a Supreme Being, one is free to hold whatever
beliefs there are in one. Saying that "evolutionists are
atheists" is just like saying "apple-lovers are orangehaters." One can like (or dislike) both apples and oranges.
_Scientists believe in evolution as their religion since
they do not believe in God._ The religious beliefs of
scientists are as varied as it is in any group of
professional people. Unfortunately our secondary school
textbooks and various media sources like to use the phrase
"Scientists believe..." whenever they present evolution as
if the scientists hold a unique religious belief. This is
especially harmful when facts are presented, because it
gives the student or layperson the idea that the facts are
not supported by evidence and can be accepted as
questionable. What would happen if a teacher were to say,
"Mathematicians believe that 5x6=30" or "Historians believe
that we fought a civil war in the 1860's?" Instead of
saying "Scientists believe in evolution" one should say
"Scientists accept evolution based on the overwhelming
objective evidence in its favor."
_Evolution is "The Big Lie" that Satan tempted Eve with
in the Garden of Eden._ This may not sound like a scientific
statement, but it is repeated frequently by the "scientific
creationists." In fact one such group, the Institute for
Creation Research, publishes a book entitled The Lie:
Evolution with a large poster showing a serpent holding an
apple marked EVOLUTION. These people state that scientists
lie while they spread "The Truth." So then what is "The
Truth?"
Creationists are the masters of prevarication. In
their presentations they frequently make false statements
about science and scientists; anyone familiar with biology
or geology can spot them. Then why do they do it?
One reason could be that they are ignorant about
science and, therefore, make many mistakes. However, they
say that they are experts on evolution and have some degree
in engineering or theology to prove it. A practicing
scientist knows these statements are false and ridiculous;
many of us have exposed them as such. Then why are they
still frequently repeated?
The other possibility is that these anti-evolutionists
know the statements are false, yet repeat them anyway. Many
of the "scientific creationist" debaters make statements
they cannot prove; in fact, many scientists have proved
their claims as false and they have admitted their error.
Yet in their next debate or presentation, they repeat these
falsehoods unabatedly.
I can show anyone the scientific evidence to support
what I said above. This is more than what "scientific
creationists" can do. In this country anybody can hold
whatever religious beliefs they want to; however, when they
say that these beliefs are scientific and should be taught
in public schools, they must produce evidence to support
what they say. I have always found it amazing how many
falsehoods and distortions are said by those spreading "The
Truth."
There are many more misunderstandings about evolution
which a quality science education will expose. Until such
teaching becomes the standard, we scientists and educators
need to reveal these myths for what they are--an attempt to
mislead the public and discredit the scientists and teachers
who have devoted their lives to increasing our knowledge of
the universe solely for the purpose of converting students
and the public to a specific religious belief system.
-------------[This article was the basis for Traxler's lecture before the
Missouri Association for Creationism meeting in April, 1991.
Ransom R. Traxler is the Director of the St. Louis
Association for the Teaching of Evolution (SLATE), P.O. Box 462,
O'Fallon, IL 62269-0462. This article reprinted with permission
from the May/June 1991 issue of _The American Rationalist_.
Permission to reprint this article must be obtained in writing from
_The American Rationalist_, P.O. Box 994, St. Louis, MO 63188.]