As recently as 1966, sheik Abd el Aziz bin Baz asked the king ofSaudi Arabia to suppress a heresy that was spreading in his land.Wrote the sheik:

"The Holy Koran, the Prophet's teachings, the majority of Islamicscientists, and the actual facts all prove that the sun is running inits orbit... and that the earth is fixed and stable, spread out by Godfor his mankind.... Anyone who professed otherwise would utter a chargeof falsehood toward God, the Koran, and the Prophet."

The good sheik evidently holds the Copernican theory to be a "meretheory," not a "fact." In this he is technically correct. A theory canbe verified by a mass of facts, but it becomes a proven theory, not afact. The sheik was perhaps unaware that the Space Age had begun beforehe asked the king to suppress the Copernican heresy. The sphericity ofthe earth has been seen by astronauts, and even by many earth-boundpeople on their television screens. Perhaps the sheik could retort thatthose 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 theearth rotates around the sun, and not vice versa, have not been verifiedby direct observations even to the extent the sphericity of the earth hasbeen. Yet scientists accept the model as an accurate representation ofreality. Why? Because it makes sense of a multitude of facts which areotherwise meaningless or extravagant. To non-specialists most of thesefacts are unfamiliar. Why then do we accept the "mere theory" that theearth is a sphere revolving around a spherical sun? Are we simplysubmitting to authority? Not quite: we know that those who took thetime 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. TheKoran and the Bible do not contradict Copernicus, nor does Copernicuscontradict them. It is ludicrous to mistake the Bible and the Koran forprimers of natural science. They treat of matters even more important:the meaning of man and his relations to God. They are written in poeticsymbols that were understandable to people of the age when they werewritten, as well as to peoples of all other ages. The king of Arabia didnot comply with the sheik's demand. He knew that some people fearenlightenment, 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 maybe 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 inapproximately its present state in 4004 BC. The estimates of the age ofthe universe given by modern cosmologists are still only roughapproximations, which are revised (usually upward) as the methods ofestimation are refined. Some cosmologists take the universe to be about10 billion years old; others suppose that it may have existed, and willcontinue to exist, eternally. The origin of life on earth is datedtentatively between 3 and 5 billion years ago; manlike beings appearedrelatively quite recently, between 2 and 4 million years ago. Theestimates of the age of the earth, of the duration of the geologic andpaleontologic eras, and of the antiquity of man's ancestors are now basedmainly on radiometric evidence the proportions of isotopes of certainchemical 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 supposethat the Creator saw fit to play deceitful tricks on geologists andbiologists. He carefully arranged to have various rocks provided withisotope ratios just right to mislead us into thinking that certain rocksare 2 billion years old, others 2 million, which in fact they are onlysome 6,000 years old. This kind of pseudo-explanation is not very new.One of the early anti-evolutionists, P. H. Gosse, published a bookentitled Omphalos ("the Navel"). The gist of this amazing book isthat Adam, though he had no mother, was created with a navel, and thatfossils were placed by the Creator where we find them now -- a deliberateact on His part, to give the appearance of great antiquity and geologicupheavals. It is easy to see the fatal flaw in all such notions. They areblasphemies, accusing God of absurd deceitfulness. This is as revoltingas it is uncalled for.

Diversity of Living Beings

The diversity and the unity of life are equally striking and meaningfulaspects of the living world. Between 1.5 and 2 million species of animalsand plants have been described and studied; the number yet to be describedis probably as great. The diversity of sizes, structures, and ways of lifeis staggering but fascinating. Here are just a few examples.

The foot-and-mouth disease virus is a sphere 8-12 mm in diameter. Theblue whale reaches 30 m in length and 135 t in weight. The simplest virusesare parasites in cells of other organisms, reduced to barest essentialsminute amounts of DNA or RNA, which subvert the biochemical machinery ofthe host cells to replicate their genetic information, rather than thatof the host.

It is a matter of opinion, or of definition, whether viruses areconsidered living organisms or peculiar chemical substances. The factthat such differences of opinion can exist is in itself highly significant.It means that the borderline between living and inanimate matter isobliterated. At the opposite end of the simplicity complexity spectrumyou have vertebrate animals, including man. The human brain has some 12billion neurons; the synapses between the neurons are perhaps a thousandtimes numerous.

Some organisms live in a great variety of environments. Man is atthe top of the scale in this respect. He is not only a truly cosmopolitanspecies but, owing to his technologic achievements, can survive for atleast a limited time on the surface of the moon and in cosmic spaces. Bycontrast, some organisms are amazingly specialized. Perhaps the narrowestecologic niche of all is that of a species of the fungus familyLaboulbeniaceae, which grows exclusively on the rear portion of theelytra of the beetle Aphenops cronei, which is found only in somelimestone caves in southern France. Larvae of the fly Psilopa petroleidevelop in seepages of crude oil in California oilfields; as far as is knownthey occur nowhere else. This is the only insect able to live and feed inoil, and its adult can walk on the surface of the oil only as long as nobody part other than the tarsi are in contact with the oil. Larvae of thefly Drosophila carciniphila develop only in the nephric groovesbeneath the flaps of the third maxilliped of the land crab Geocarcinusruricola, which is restricted to certain islands in the Caribbean.

Is there an explanation, to make intelligible to reason this colossaldiversity of living beings? Whence came these extraordinary, seeminglywhimsical and superfluous creatures, like the fungus Laboulbenia,the beetle Aphenops cronei, the flies Psilopa petroleiand Drosophila carciniphila, and many, many more apparent biologiccuriosities? The only explanation that makes sense is that the organicdiversity has evolved in response to the diversity of environment on theplanet earth. No single species, however perfect and however versatile,could exploit all the opportunities for living. Every one of the millionsof species has its own way of living and of getting sustenance from theenvironment. There are doubtless many other possible ways of living asyet unexploited by any existing species; but one thing is clear: withless organic diversity, some opportunities for living would remainunexploited. The evolutionary process tends to fill up the availableecologic niches. It does not do so consciously or deliberately; therelations between evolution and environment are more subtle and moreinteresting than that. The environment does not impose evolutionarychanges on its inhabitants, as postulated by the now abandonedneo-Lamarckian theories. The best way to envisage the situation is asfollows: the environment presents challenges to living species, to whichthe 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 climategiving place to a warmer climate. Natural selection may cause a livingspecies to respond to the challenge by adaptive genetic changes. Thesechanges may enable the species to occupy the formerly empty ecologicniche as a new opportunity for living, or to resist the environmentalchange 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 compositionof the responding species at the time the response is called for. Lack ofsuccessful response may cause the species to become extinct. The evidenceof fossils shows clearly that the eventual end of most evolutionary linesis extinction. Organisms now living are successful descendants of only aminority of the species that lived in the past and of smaller and smallerminorities the farther back you look. Nevertheless, the number of livingspecies has not dwindled; indeed, it has probably grown with time. Allthis is understandable in the light of evolution theory; but what asenseless operation it would have been, on God's part, to fabricate amultitude of species ex nihilo and then let most of them die out!

There is, of course, nothing conscious or intentional in the actionof natural selection. A biologic species does not say to itself, "Let metry 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 differentcrab." Only a human being could make such conscious decisions. This iswhy the species Homo sapiens is the apex of evolution. Naturalselection is at one and the same time a blind and creative process.Only a creative and blind process could produce, on the one hand, thetremendous biologic success that is the human species and, on the other,forms of adaptedness as narrow and as constraining as those of theoverspecialized fungus, beetle, and flies mentioned above.

Anti-evolutionists fail to understand how natural selection operates.They fancy that all existing species were generated by supernaturalfiat a few thousand years ago, pretty much as we find them today. Butwhat is the sense of having as many as 2 or 3 million species livingon earth? If natural selection is the main factor that brings evolutionabout, any number of species is understandable: natural selection doesnot work according to a foreordained plan, and species are produced notbecause they are needed for some purpose but simply because there is anenvironmental opportunity and genetic wherewithal to make them possible.Was the Creator in a jocular mood when he made Psilopa petroleifor California oil fields and species of Drosophila to liveexclusively on some body-parts of certain land crabs on only certainislands in the Caribbean? The organic diversity becomes, however,reasonable and understandable if the Creator has created the livingworld not by caprice but by evolution propelled by natural selection.It is wrong to hold creation and evolution as mutually exclusivealternatives. I am a creationist and an evolutionist. Evolution isGod's, or Nature's method of creation. Creation is not an event thathappened in 4004 BC; it is a process that began some 10 billion yearsago and is still under way.

Unity of Life

The unity of life is no less remarkable than its diversity. Mostforms of life are similar in many respects. The universal biologicsimilarities are particularly striking in the biochemical dimension.From viruses to man, heredity is coded in just two, chemically relatedsubstances: 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 evolutionarydevelopment of the living world has taken place not by invention of new"letters" in the genetic "alphabet" but by elaboration of ever-newcombinations of these letters.

Not only is the DNA-RNA genetic code universal, but so is themethod of translation of the sequences of the "letters" in DNA-RNAinto sequences of amino acids in proteins. The same 20 amino acidscompose countless different proteins in all, or at least in most,organisms. Different amino acids are coded by one to six nucleotidetriplets in DNA and RNA. And the biochemical universals extend beyondthe genetic code and its translation into proteins: strikinguniformities prevail in the cellular metabolism of the most diverseliving beings. Adenosine triphosphate, biotin, riboflavin, hemes,pyridoxin, vitamins K and B12, and folic acid implement metabolicprocesses everywhere.

What do these biochemical or biologic universals mean? They suggestthat life arose from inanimate matter only once and that all organisms,no matter now diverse, in other respects, conserve the basic featuresof 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 themhas survived and inherited the earth.) But what if there was noevolution and every one of the millions of species were created byseparate fiat? However offensive the notion may be to religiousfeeling and to reason, the anti-evolutionists must again accuse theCreator of cheating. They must insist that He deliberately arrangedthings exactly as if his method of creation was evolution, intentionallyto mislead sincere seekers of truth.

The remarkable advances of molecular biology in recent years have madeit possible to understand how it is that diverse organisms are constructedfrom such monotonously similar materials: proteins composed of only 20kinds of amino acids and coded only by DNA and RNA, each with only fourkinds of nucleotides. The method is astonishingly simple. All Englishwords, sentences, chapters, and books are made up of sequences of 26letters of the alphabet. (They can be represented also by only threesigns of the Morse code: dot, dash, and gap.) The meaning of a word ora sentence is defined not so much by what letters it contains as by thesequences of these letters. It is the same with heredity: it is coded bythe sequences of the genetic "letters" the nucleotides in the DNA. Theyare translated into the sequences of amino acids in the proteins.

Molecular studies have made possible an approach to exact measurementsof degrees of biochemical similarities and differences among organisms.Some kinds of enzymes and other proteins are quasi-universal, or at anyrate widespread, in the living world. They are functionally similar indifferent living beings, in that they catalyze similar chemical reactions.But when such proteins are isolated and their structures determinedchemically, they are often found to contain more or less differentsequences of amino acids in different organisms. For example, theso-called alpha chains of hemoglobin have identical sequences of aminoacids in man and the chimpanzee, but they differ in a single amino acid(out of 141) in the gorilla. Alpha chains of human hemoglobin differfrom 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 metabolismof aerobic cells. It is found in the most diverse organisms, from manto molds. E. Margoliash, W. M. Fitch, and others have compared theamino acid sequences in cytochrome C in different branches of the livingworld. Most significant similarities as well as differences have beenbrought to light. The cytochrome C of different orders of mammals andbirds 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 yeastsand molds in 56 to 72 amino acids. Fitch and Margoliash prefer to expresstheir findings in what are called "minimal mutational distances." It hasbeen mentioned above that different amino acids are coded by differenttriplets of nucleotides in DNA of the genes; this code is now known.Most mutations involve substitutions of single nucleotides somewherein the DNA chain coding for a given protein. Therefore, one can calculatethe minimum numbers of single mutations needed to change the cytochromeC of one organism into that of another. Minimal mutational distancesbetween human cytochrome C and the cytochrome C of other living beingsare as follows:

It is important to note that amino acid sequences in a given kindof 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 thatvary also among individuals within a species. Individual and groupdifferences are only quantitatively, not qualitatively, different.Evidence supporting the above propositions is ample and is growingrapidly. Much work has been done in recent years on individual variationsin amino acid sequences of hemoglobin of human blood. More that 100variants have been detected. Most of them involve substitutions ofsingle amino acids - substitutions that have arisen by genetic mutationsin the persons in whom they are discovered or in their ancestors. Asexpected, 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 onefamily; others are discovered repeatedly among inhabitants of differentparts of the world. I submit that all these remarkable findings makesense in the light of evolution: they are nonsense otherwise.

Comparative Anatomy and Embryology

The biochemical universals are the most impressive and the mostrecently discovered, but certainly they are not the only vestiges ofcreation by means of evolution. Comparative anatomy and embryologyproclaim the evolutionary origins of the present inhabitants of theworld. In 1555 Pierre Belon established the presence of homologousbones in the superficially very different skeletons of man and bird.Later anatomists traced the homologies in the skeletons, as well asin other organs, of all vertebrates. Homologies are also traceablein the external skeletons of arthropods as seemingly unlike as alobster, a fly, and a butterfly. Examples of homologies can be multipliedindefinitely.

Embryos of apparently quite diverse animals often exhibit strikingsimilarities. A century ago these similarities led some biologists(notably the German zoologist Ernst Haeckel) to be carried by theirenthusiasm as far as to interpret the embryonic similarities as meaningthat the embryo repeats in its development the evolutionary history ofits species: it was said to pass through stages in which it resemblesits remote ancestors. In other words, early-day biologists supposed thatby studying embryonic development one can, as it were, read off the stagesthrough which the evolutionary development had passed. This so-calledbiogenetic law is no longer credited in its original form. And yetembryonic similarities are undeniable impressive and significant.

Probably everybody knows the sedentary barnacles which seem to haveno similarity to free-swimming crustaceans, such as the copepods. Howremarkable that barnacles pass through a free-swimming larval stage,the nauplius! At that stage of its development a barnacle and a Cyclopslook unmistakably similar. They are evidently relatives. The presence ofgill slits in human embryos and in embryos of other terrestrialvertebrates is another famous example. Of course, at no stage of itsdevelopment is a human embryo a fish, nor does it ever have functioninggills. But why should it have unmistakable gill slits unless its remoteancestors did respire with the aid of gills? It is the Creator againplaying practical jokes?

Adaptive radiation: Hawaii's Flies

There are about 2,000 species of drosophilid flies in the world as awhole. About a quarter of them occur in Hawaii, although the total areaof the archipelago is only about that of the state of New Jersey. Allbut 17 of the species in Hawaii are endemic (found nowhere else).Furthermore, a great majority of the Hawaiian endemics do not occurthroughout the archipelago: they are restricted to single islands oreven to a part of an island. What is the explanation of this extraordinaryproliferation of drosophilid species in so small a territory? Recent workof H. L. Carson, H. T. Spieth, D. E. Hardy, and others makes the situationunderstandable.

The Hawaiian Islands are of volcanic origin; they were never parts ofany continent. Their ages are between 5.6 and 0.7 million years. Beforeman came there inhabitants were descendants of immigrants that had beentransported across the ocean by air currents and other accidental means.A single drosophilid species, which arrived in Hawaii first, before therewere numerous competitors, faced the challenge of an abundance of manyunoccupied ecologic niches. Its descendants responded to this challengeby evolutionary adaptive radiation, the products of which are the remarkableHawaiian drosophilids of today. To forestall a possible misunderstanding,let it be made clear that the Hawaiian endemics are by no means so similarto each other that they could be mistaken for variants of the same species;if anything, they are more diversified than are drosophilids elsewhere. Thelargest and the smallest drosophilid species are both Hawaiian. They exhibitan astonishing variety of behavior patterns. Some of them have become adaptedto ways of life quite extraordinary for a drosophilid fly, such as beingparasites 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 mostprobable explanation of this fact is that these other islands werecolonized by drosophilid after most ecologic niches had already beenfilled by earlier arrivals. This surely is a hypothesis, but it is areasonable one. Anti-evolutionists might perhaps suggest an alternativehypothesis: in a fit of absentmindedness, the Creator went on manufacturingmore and more drosophilid species for Hawaii, until there was an extravagantsurfeit of them in this archipelago. I leave it up to you to decide whichhypothesis makes sense.

Strength and Acceptance of the Theory

Seen in the light of evolution, biology is, perhaps, intellectually themost satisfying and inspiring science. Without that light it becomes apile of sundry facts some of them interesting or curious but making nomeaningful picture as a whole.

This is not to imply that we know everything that can and should beknown about biology and about evolution. Any competent biologist is awareof a multitude of problems yet unresolved and of questions yet unanswered.After all, biologic research shows no sign of approaching completion; quitethe opposite is true. Disagreements and clashes of opinion are rife amongbiologists, as they should be in a living and growing science.Anti-evolutionists mistake, or pretend to mistake, these disagreementsas indications of dubiousness of the entire doctrine of evolution. Theirfavorite sport is stringing together quotations, carefully and sometimesexpertly taken out of context, to show that nothing is really establishedor agreed upon among evolutionists. Some of my colleagues and myself havebeen amused and amazed to read ourselves quoted in a way showing that weare really anti-evolutionists under the skin.

Let me try to make crystal clear what is established beyond reasonabledoubt, and what needs further study, about evolution. Evolution as aprocess that has always gone on in the history of the earth can be doubtedonly by those who are ignorant of the evidence or are resistant to evidence,owing to emotional blocks or to plain bigotry. By contrast, the mechanismsthat bring evolution about certainly need study and clarification. Thereare no alternatives to evolution as history that can withstand criticalexamination. Yet we are constantly learning new and important facts aboutevolutionary mechanisms.

It is remarkable that more than a century ago Darwin was able to discernso much about evolution without having available to him the key factsdiscovered since. The development of genetics after 1900 especially ofmolecular genetics, in the last two decades has provided informationessential to the understanding of evolutionary mechanisms. But much isin doubt and much remains to be learned. This is heartening and inspiringfor any scientist worth his salt. Imagine that everything is completelyknown and that science has nothing more to discover: what a nightmare!

Does the evolutionary doctrine clash with religious faith? It doesnot. It is a blunder to mistake the Holy Scriptures for elementarytextbooks of astronomy, geology, biology, and anthropology. Only ifsymbols are construed to mean what they are not intended to mean canthere arise imaginary, insoluble conflicts. As pointed out above, theblunder leads to blasphemy: the Creator is accused of systematicdeceitfulness.

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, allhypotheses, all systems much henceforward bow and which they must satisfyin order to be thinkable and true. Evolution is a light which illuminatesall facts, a trajectory which all lines of though must follow this iswhat evolution is. Of course, some scientists, as well as somephilosophers and theologians, disagree with some parts of Teilhard'steachings; the acceptance of his worldview falls short of universal.But there is no doubt at all that Teilhard was a truly and deeplyreligious man and that Christianity was the cornerstone of his worldview.Moreover, in his worldview science and faith were not segregated inwatertight compartments, as they are with so many people. They wereharmoniously fitting parts of his worldview. Teilhard was a creationist,but one who understood that the Creation is realized in this world bymeans of evolution.

- Theodosius Dobzhansky, "Nothing in biology makes sense except in the light of evolution." The American BiologyTeacher, March 1973

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