As recently as 1966, sheik Abd el Aziz bin Baz asked the king of
Saudi Arabia to suppress a heresy that was spreading in his land.
Wrote the sheik:
"The Holy Koran, the Prophet's teachings, the majority of Islamic
scientists, and the actual facts all prove that the sun is running in
its orbit... and that the earth is fixed and stable, spread out by God
for his mankind.... Anyone who professed otherwise would utter a charge
of falsehood toward God, the Koran, and the Prophet."
The good sheik evidently holds the Copernican theory to be a "mere
theory," not a "fact." In this he is technically correct. A theory can
be verified by a mass of facts, but it becomes a proven theory, not a
fact. The sheik was perhaps unaware that the Space Age had begun before
he asked the king to suppress the Copernican heresy. The sphericity of
the earth has been seen by astronauts, and even by many earth-bound
people on their television screens. Perhaps the sheik could retort that
those who venture beyond the confines of God's earth suffer hallucinations,
and that the earth is really flat.
Parts of the Copernican world model, such as the contention that the
earth rotates around the sun, and not vice versa, have not been verified
by direct observations even to the extent the sphericity of the earth has
been. Yet scientists accept the model as an accurate representation of
reality. Why? Because it makes sense of a multitude of facts which are
otherwise meaningless or extravagant. To non-specialists most of these
facts are unfamiliar. Why then do we accept the "mere theory" that the
earth is a sphere revolving around a spherical sun? Are we simply
submitting to authority? Not quite: we know that those who took the
time to study the evidence found it convincing.
The good sheik is probably ignorant of the evidence. Even more likely,
he is so hopelessly biased that no amount of evidence would impress him.
Anyway, it would be sheer waste of time to attempt to convince him. The
Koran and the Bible do not contradict Copernicus, nor does Copernicus
contradict them. It is ludicrous to mistake the Bible and the Koran for
primers of natural science. They treat of matters even more important:
the meaning of man and his relations to God. They are written in poetic
symbols that were understandable to people of the age when they were
written, as well as to peoples of all other ages. The king of Arabia did
not comply with the sheik's demand. He knew that some people fear
enlightenment, because enlightenment threatens their vested interests.
Education is not to be used to promote obscurantism.
The earth is not the geometric center of the universe, although it may
be its spiritual center. It is a mere speck of dust in the cosmic spaces.
Contrary to Bishop Ussher's calculations, the world did not appear in
approximately its present state in 4004 BC. The estimates of the age of
the universe given by modern cosmologists are still only rough
approximations, which are revised (usually upward) as the methods of
estimation are refined. Some cosmologists take the universe to be about
10 billion years old; others suppose that it may have existed, and will
continue to exist, eternally. The origin of life on earth is dated
tentatively between 3 and 5 billion years ago; manlike beings appeared
relatively quite recently, between 2 and 4 million years ago. The
estimates of the age of the earth, of the duration of the geologic and
paleontologic eras, and of the antiquity of man's ancestors are now based
mainly on radiometric evidence the proportions of isotopes of certain
chemical elements in rocks suitable for such studies.
Shiek bin Baz and his like refuse to accept the radiometric evidence,
because it is a "mere theory." What is the alternative? One can suppose
that the Creator saw fit to play deceitful tricks on geologists and
biologists. He carefully arranged to have various rocks provided with
isotope ratios just right to mislead us into thinking that certain rocks
are 2 billion years old, others 2 million, which in fact they are only
some 6,000 years old. This kind of pseudo-explanation is not very new.
One of the early anti-evolutionists, P. H. Gosse, published a book
entitled Omphalos ("the Navel"). The gist of this amazing book is
that Adam, though he had no mother, was created with a navel, and that
fossils were placed by the Creator where we find them now -- a deliberate
act on His part, to give the appearance of great antiquity and geologic
upheavals. It is easy to see the fatal flaw in all such notions. They are
blasphemies, accusing God of absurd deceitfulness. This is as revolting
as it is uncalled for.
Diversity of Living Beings
The diversity and the unity of life are equally striking and meaningful
aspects of the living world. Between 1.5 and 2 million species of animals
and plants have been described and studied; the number yet to be described
is probably as great. The diversity of sizes, structures, and ways of life
is staggering but fascinating. Here are just a few examples.
The foot-and-mouth disease virus is a sphere 8-12 mm in diameter. The
blue whale reaches 30 m in length and 135 t in weight. The simplest viruses
are parasites in cells of other organisms, reduced to barest essentials
minute amounts of DNA or RNA, which subvert the biochemical machinery of
the host cells to replicate their genetic information, rather than that
of the host.
It is a matter of opinion, or of definition, whether viruses are
considered living organisms or peculiar chemical substances. The fact
that such differences of opinion can exist is in itself highly significant.
It means that the borderline between living and inanimate matter is
obliterated. At the opposite end of the simplicity complexity spectrum
you have vertebrate animals, including man. The human brain has some 12
billion neurons; the synapses between the neurons are perhaps a thousand
Some organisms live in a great variety of environments. Man is at
the top of the scale in this respect. He is not only a truly cosmopolitan
species but, owing to his technologic achievements, can survive for at
least a limited time on the surface of the moon and in cosmic spaces. By
contrast, some organisms are amazingly specialized. Perhaps the narrowest
ecologic niche of all is that of a species of the fungus family
Laboulbeniaceae, which grows exclusively on the rear portion of the
elytra of the beetle Aphenops cronei, which is found only in some
limestone caves in southern France. Larvae of the fly Psilopa petrolei
develop in seepages of crude oil in California oilfields; as far as is known
they occur nowhere else. This is the only insect able to live and feed in
oil, and its adult can walk on the surface of the oil only as long as no
body part other than the tarsi are in contact with the oil. Larvae of the
fly Drosophila carciniphila develop only in the nephric grooves
beneath the flaps of the third maxilliped of the land crab Geocarcinus
ruricola, which is restricted to certain islands in the Caribbean.
Is there an explanation, to make intelligible to reason this colossal
diversity of living beings? Whence came these extraordinary, seemingly
whimsical and superfluous creatures, like the fungus Laboulbenia,
the beetle Aphenops cronei, the flies Psilopa petrolei
and Drosophila carciniphila, and many, many more apparent biologic
curiosities? The only explanation that makes sense is that the organic
diversity has evolved in response to the diversity of environment on the
planet earth. No single species, however perfect and however versatile,
could exploit all the opportunities for living. Every one of the millions
of species has its own way of living and of getting sustenance from the
environment. There are doubtless many other possible ways of living as
yet unexploited by any existing species; but one thing is clear: with
less organic diversity, some opportunities for living would remain
unexploited. The evolutionary process tends to fill up the available
ecologic niches. It does not do so consciously or deliberately; the
relations between evolution and environment are more subtle and more
interesting than that. The environment does not impose evolutionary
changes on its inhabitants, as postulated by the now abandoned
neo-Lamarckian theories. The best way to envisage the situation is as
follows: the environment presents challenges to living species, to which
the later may respond by adaptive genetic changes.
An unoccupied ecologic niche, an unexploited opportunity for living,
is a challenge. So is an environmental change, such as the Ice Age climate
giving place to a warmer climate. Natural selection may cause a living
species to respond to the challenge by adaptive genetic changes. These
changes may enable the species to occupy the formerly empty ecologic
niche as a new opportunity for living, or to resist the environmental
change if it is unfavorable. But the response may or may not be successful.
This depends on many factors, the chief of which is the genetic composition
of the responding species at the time the response is called for. Lack of
successful response may cause the species to become extinct. The evidence
of fossils shows clearly that the eventual end of most evolutionary lines
is extinction. Organisms now living are successful descendants of only a
minority of the species that lived in the past and of smaller and smaller
minorities the farther back you look. Nevertheless, the number of living
species has not dwindled; indeed, it has probably grown with time. All
this is understandable in the light of evolution theory; but what a
senseless operation it would have been, on God's part, to fabricate a
multitude of species ex nihilo and then let most of them die out!
There is, of course, nothing conscious or intentional in the action
of natural selection. A biologic species does not say to itself, "Let me
try tomorrow (or a million years from now) to grow in a different soil,
or use a different food, or subsist on a different body part of a different
crab." Only a human being could make such conscious decisions. This is
why the species Homo sapiens is the apex of evolution. Natural
selection is at one and the same time a blind and creative process.
Only a creative and blind process could produce, on the one hand, the
tremendous biologic success that is the human species and, on the other,
forms of adaptedness as narrow and as constraining as those of the
overspecialized fungus, beetle, and flies mentioned above.
Anti-evolutionists fail to understand how natural selection operates.
They fancy that all existing species were generated by supernatural
fiat a few thousand years ago, pretty much as we find them today. But
what is the sense of having as many as 2 or 3 million species living
on earth? If natural selection is the main factor that brings evolution
about, any number of species is understandable: natural selection does
not work according to a foreordained plan, and species are produced not
because they are needed for some purpose but simply because there is an
environmental opportunity and genetic wherewithal to make them possible.
Was the Creator in a jocular mood when he made Psilopa petrolei
for California oil fields and species of Drosophila to live
exclusively on some body-parts of certain land crabs on only certain
islands in the Caribbean? The organic diversity becomes, however,
reasonable and understandable if the Creator has created the living
world not by caprice but by evolution propelled by natural selection.
It is wrong to hold creation and evolution as mutually exclusive
alternatives. I am a creationist and an evolutionist. Evolution is
God's, or Nature's method of creation. Creation is not an event that
happened in 4004 BC; it is a process that began some 10 billion years
ago and is still under way.
Unity of Life
The unity of life is no less remarkable than its diversity. Most
forms of life are similar in many respects. The universal biologic
similarities are particularly striking in the biochemical dimension.
From viruses to man, heredity is coded in just two, chemically related
substances: DNA and RNA. The genetic code is as simple as it is universal.
There are only four genetic "letters" in DNA: adenine, guanine, thymine,
and cytosine. Uracil replaces thymine in RNA. The entire evolutionary
development of the living world has taken place not by invention of new
"letters" in the genetic "alphabet" but by elaboration of ever-new
combinations of these letters.
Not only is the DNA-RNA genetic code universal, but so is the
method of translation of the sequences of the "letters" in DNA-RNA
into sequences of amino acids in proteins. The same 20 amino acids
compose countless different proteins in all, or at least in most,
organisms. Different amino acids are coded by one to six nucleotide
triplets in DNA and RNA. And the biochemical universals extend beyond
the genetic code and its translation into proteins: striking
uniformities prevail in the cellular metabolism of the most diverse
living beings. Adenosine triphosphate, biotin, riboflavin, hemes,
pyridoxin, vitamins K and B12, and folic acid implement metabolic
What do these biochemical or biologic universals mean? They suggest
that life arose from inanimate matter only once and that all organisms,
no matter now diverse, in other respects, conserve the basic features
of the primordial life. (It is also possible that there were several,
or even many, origins of life; if so, the progeny of only one of them
has survived and inherited the earth.) But what if there was no
evolution and every one of the millions of species were created by
separate fiat? However offensive the notion may be to religious
feeling and to reason, the anti-evolutionists must again accuse the
Creator of cheating. They must insist that He deliberately arranged
things exactly as if his method of creation was evolution, intentionally
to mislead sincere seekers of truth.
The remarkable advances of molecular biology in recent years have made
it possible to understand how it is that diverse organisms are constructed
from such monotonously similar materials: proteins composed of only 20
kinds of amino acids and coded only by DNA and RNA, each with only four
kinds of nucleotides. The method is astonishingly simple. All English
words, sentences, chapters, and books are made up of sequences of 26
letters of the alphabet. (They can be represented also by only three
signs of the Morse code: dot, dash, and gap.) The meaning of a word or
a sentence is defined not so much by what letters it contains as by the
sequences of these letters. It is the same with heredity: it is coded by
the sequences of the genetic "letters" the nucleotides in the DNA. They
are translated into the sequences of amino acids in the proteins.
Molecular studies have made possible an approach to exact measurements
of degrees of biochemical similarities and differences among organisms.
Some kinds of enzymes and other proteins are quasi-universal, or at any
rate widespread, in the living world. They are functionally similar in
different living beings, in that they catalyze similar chemical reactions.
But when such proteins are isolated and their structures determined
chemically, they are often found to contain more or less different
sequences of amino acids in different organisms. For example, the
so-called alpha chains of hemoglobin have identical sequences of amino
acids in man and the chimpanzee, but they differ in a single amino acid
(out of 141) in the gorilla. Alpha chains of human hemoglobin differ
from cattle hemoglobin in 17 amino acid substitutions, 18 from horse,
20 from donkey, 25 from rabbit, and 71 from fish (carp).
Cytochrome C is an enzyme that plays an important role in the metabolism
of aerobic cells. It is found in the most diverse organisms, from man
to molds. E. Margoliash, W. M. Fitch, and others have compared the
amino acid sequences in cytochrome C in different branches of the living
world. Most significant similarities as well as differences have been
brought to light. The cytochrome C of different orders of mammals and
birds differ in 2 to 17 amino acids, classes of vertebrates in 7 to 38,
and vertebrates and insects in 23 to 41; and animals differ from yeasts
and molds in 56 to 72 amino acids. Fitch and Margoliash prefer to express
their findings in what are called "minimal mutational distances." It has
been mentioned above that different amino acids are coded by different
triplets of nucleotides in DNA of the genes; this code is now known.
Most mutations involve substitutions of single nucleotides somewhere
in the DNA chain coding for a given protein. Therefore, one can calculate
the minimum numbers of single mutations needed to change the cytochrome
C of one organism into that of another. Minimal mutational distances
between human cytochrome C and the cytochrome C of other living beings
are as follows:
It is important to note that amino acid sequences in a given kind
of protein vary within a species as well as from species to species.
It is evident that the differences among proteins at the level of species,
genus, family, order, class, and phylum are compounded of elements that
vary also among individuals within a species. Individual and group
differences are only quantitatively, not qualitatively, different.
Evidence supporting the above propositions is ample and is growing
rapidly. Much work has been done in recent years on individual variations
in amino acid sequences of hemoglobin of human blood. More that 100
variants have been detected. Most of them involve substitutions of
single amino acids - substitutions that have arisen by genetic mutations
in the persons in whom they are discovered or in their ancestors. As
expected, some of these mutations are deleterious to their carriers,
but others apparently are neutral or even favorable in certain environments.
Some mutant hemoglobins have been found only in one person or in one
family; others are discovered repeatedly among inhabitants of different
parts of the world. I submit that all these remarkable findings make
sense in the light of evolution: they are nonsense otherwise.
Comparative Anatomy and Embryology
The biochemical universals are the most impressive and the most
recently discovered, but certainly they are not the only vestiges of
creation by means of evolution. Comparative anatomy and embryology
proclaim the evolutionary origins of the present inhabitants of the
world. In 1555 Pierre Belon established the presence of homologous
bones in the superficially very different skeletons of man and bird.
Later anatomists traced the homologies in the skeletons, as well as
in other organs, of all vertebrates. Homologies are also traceable
in the external skeletons of arthropods as seemingly unlike as a
lobster, a fly, and a butterfly. Examples of homologies can be multiplied
Embryos of apparently quite diverse animals often exhibit striking
similarities. A century ago these similarities led some biologists
(notably the German zoologist Ernst Haeckel) to be carried by their
enthusiasm as far as to interpret the embryonic similarities as meaning
that the embryo repeats in its development the evolutionary history of
its species: it was said to pass through stages in which it resembles
its remote ancestors. In other words, early-day biologists supposed that
by studying embryonic development one can, as it were, read off the stages
through which the evolutionary development had passed. This so-called
biogenetic law is no longer credited in its original form. And yet
embryonic similarities are undeniable impressive and significant.
Probably everybody knows the sedentary barnacles which seem to have
no similarity to free-swimming crustaceans, such as the copepods. How
remarkable that barnacles pass through a free-swimming larval stage,
the nauplius! At that stage of its development a barnacle and a Cyclops
look unmistakably similar. They are evidently relatives. The presence of
gill slits in human embryos and in embryos of other terrestrial
vertebrates is another famous example. Of course, at no stage of its
development is a human embryo a fish, nor does it ever have functioning
gills. But why should it have unmistakable gill slits unless its remote
ancestors did respire with the aid of gills? It is the Creator again
playing practical jokes?
Adaptive radiation: Hawaii's Flies
There are about 2,000 species of drosophilid flies in the world as a
whole. About a quarter of them occur in Hawaii, although the total area
of the archipelago is only about that of the state of New Jersey. All
but 17 of the species in Hawaii are endemic (found nowhere else).
Furthermore, a great majority of the Hawaiian endemics do not occur
throughout the archipelago: they are restricted to single islands or
even to a part of an island. What is the explanation of this extraordinary
proliferation of drosophilid species in so small a territory? Recent work
of H. L. Carson, H. T. Spieth, D. E. Hardy, and others makes the situation
The Hawaiian Islands are of volcanic origin; they were never parts of
any continent. Their ages are between 5.6 and 0.7 million years. Before
man came there inhabitants were descendants of immigrants that had been
transported across the ocean by air currents and other accidental means.
A single drosophilid species, which arrived in Hawaii first, before there
were numerous competitors, faced the challenge of an abundance of many
unoccupied ecologic niches. Its descendants responded to this challenge
by evolutionary adaptive radiation, the products of which are the remarkable
Hawaiian drosophilids of today. To forestall a possible misunderstanding,
let it be made clear that the Hawaiian endemics are by no means so similar
to each other that they could be mistaken for variants of the same species;
if anything, they are more diversified than are drosophilids elsewhere. The
largest and the smallest drosophilid species are both Hawaiian. They exhibit
an astonishing variety of behavior patterns. Some of them have become adapted
to ways of life quite extraordinary for a drosophilid fly, such as being
parasites in egg cocoons of spiders.
Oceanic islands other than Hawaii, scattered over the wide Pacific Ocean,
are not conspicuously rich in endemic species of drosophilids. The most
probable explanation of this fact is that these other islands were
colonized by drosophilid after most ecologic niches had already been
filled by earlier arrivals. This surely is a hypothesis, but it is a
reasonable one. Anti-evolutionists might perhaps suggest an alternative
hypothesis: in a fit of absentmindedness, the Creator went on manufacturing
more and more drosophilid species for Hawaii, until there was an extravagant
surfeit of them in this archipelago. I leave it up to you to decide which
hypothesis makes sense.
Strength and Acceptance of the Theory
Seen in the light of evolution, biology is, perhaps, intellectually the
most satisfying and inspiring science. Without that light it becomes a
pile of sundry facts some of them interesting or curious but making no
meaningful picture as a whole.
This is not to imply that we know everything that can and should be
known about biology and about evolution. Any competent biologist is aware
of a multitude of problems yet unresolved and of questions yet unanswered.
After all, biologic research shows no sign of approaching completion; quite
the opposite is true. Disagreements and clashes of opinion are rife among
biologists, as they should be in a living and growing science.
Anti-evolutionists mistake, or pretend to mistake, these disagreements
as indications of dubiousness of the entire doctrine of evolution. Their
favorite sport is stringing together quotations, carefully and sometimes
expertly taken out of context, to show that nothing is really established
or agreed upon among evolutionists. Some of my colleagues and myself have
been amused and amazed to read ourselves quoted in a way showing that we
are really anti-evolutionists under the skin.
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 alternatives to evolution as history that can withstand critical
examination. Yet we are constantly learning new and important facts about
It is remarkable that more than a century ago Darwin was able to discern
so much about evolution without having available to him the key facts
discovered since. The development of genetics after 1900 especially of
molecular genetics, in the last two decades has provided information
essential to the understanding of evolutionary mechanisms. But much is
in doubt and much remains to be learned. This is heartening and inspiring
for any scientist worth his salt. Imagine that everything is completely
known and that science has nothing more to discover: what a nightmare!
Does the evolutionary doctrine clash with religious faith? It does
not. It is a blunder to mistake the Holy Scriptures for elementary
textbooks of astronomy, geology, biology, and anthropology. Only if
symbols are construed to mean what they are not intended to mean can
there arise imaginary, insoluble conflicts. As pointed out above, the
blunder leads to blasphemy: the Creator is accused of systematic
One of the great thinkers of our age, Pierre Teilhard de Chardin,
wrote the following: "Is evolution a theory, a system, or a hypothesis?
It is much more it is a general postulate to which all theories, all
hypotheses, all systems much henceforward bow and which they must satisfy
in order to be thinkable and true. Evolution is a light which illuminates
all facts, a trajectory which all lines of though must follow this is
what evolution is. Of course, some scientists, as well as some
philosophers and theologians, disagree with some parts of Teilhard's
teachings; the acceptance of his worldview falls short of universal.
But there is no doubt at all that Teilhard was a truly and deeply
religious man and that Christianity was the cornerstone of his worldview.
Moreover, in his worldview science and faith were not segregated in
watertight compartments, as they are with so many people. They were
harmoniously fitting parts of his worldview. Teilhard was a creationist,
but one who understood that the Creation is realized in this world by
means of evolution.
- Theodosius Dobzhansky, "Nothing in biology makes sense except in the light of evolution." The American Biology
Teacher, March 1973