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Introduction and Overview Chapters
What's Wrong With Pandas?
A Closeup Look at Creationist Scholarshipby Frank J. Sonleitner
I first became aware of the existence of the book "Of Pandas and People: The Central Question of Biological Origins" (1989. Percival Davis and Dean H. Kenyon, Haughton Publishing Company) when I attended a Bible Science Studies meeting held at the Scopes Ministries in northeast Oklahoma City on September 18, 1989. Don Patton, an associate of Carl Baugh at the Creation Evidences Museum at Glen Rose, Texas talked on two topics: The Coexistence Of Humans And Dinosaurs and How To Change The Textbooks. On the following October 23rd, the Oklahoma Board of Education textbook committee was going to hold a public hearing on the adoption of social science books for the public schools. A local creationist, Bill Nance, was trying to get support for changing some statements about the age of the earth in a world geography book that was up for adoption. Don Patton discussed the activities of the Texas creationists that were fighting the new textbook guidelines in that state. He produced a copy of this book and said it would be adopted as a supplement to the biology books in Texas. One of the advantages of this particular book was that it talked about "intelligent design" instead of scientific creationism. "Now we're not going to get scientific creationism in the textbooks; that has been ruled religious. We must avoid that term like the plague!" said Patton.
This book, which hereafter will be referred to simply as "Pandas" was not adopted as a supplement in Texas. It was also submitted for inclusion on the recommended list for science textbooks in Alabama where it was voted down. Several articles in NCSE Reports (Sept-Oct 1989, pp. 3-4; Nov-Dec, pp. 5-7; Jan-Feb. 1990, pp. 8-10) relate the details of the debate about Pandas before the Alabama textbook committee. Short reviews of the book have appeared by Eugenie Scott (NCSE Reports Jan-Feb 1990, p. 16), and by Gerald Skoog, Kevin Padian and Michael Ruse (Bookwatch Reviews 1989, vol. 2, number 11). Early in 1990, I got my copy of Pandas along with the Teacher's Guide from the publisher and decided to do an extensive in depth critique of it similar to my treatment of the six movie Origins series. I began this task towards the end of the summer and after about six months work finally finished it. Almost all the material here is new. Several of the supplements are taken from my previous document "An Evolutionist Goes to the Creationist Movies."
What's wrong with Pandas? A lot! The present critique is in the form of a running commentary on Pandas and as such necessarily contains some repetition. The sections on the Excursion chapters are heavily documented with references, both to technical papers and summary articles from such publications as Natural History magazine and Scientific American. I have probably gone overboard on this project—it contains more than 45,000 words and over 500 references and is probably longer than Pandas! But I hope that it will be of help to people who are interested in good quality science classes in our public schools.
Frank J. Sonleitner
Pandas claims a long intellectual history for evolution and creation (here called intelligent design). Many of the ancient myths only vaguely suggest evolutionary ideas and have little or no significance for the modern scientific theory of evolution. And many of them are mixtures of these two ideas. Even Genesis states that the universe was without form and its present organization was achieved in stages. White (1960) considers these ancient myths in detail.
Pandas' goal of presenting two alternative interpretations of the phenomena in six specific areas of science is laudable. Unfortunately Pandas' implementation has nothing to recommend it. Most of the facts are incorrect, many pertinent facts are omitted, many evolutionary concepts are distorted beyond recognition. For example, evolution is radically redefined. The mechanisms of evolution and punctuated equilibrium are grossly misrepresented. The nature of the fossil record is distorted and the existence of well-documented transitional forms denied. It is implied that pandas and marsupials cannot be fitted into a hierarchic classification. And finally, to discredit the protein sequencing evidence, Pandas claims that evolution requires a ladder of living forms, rather than a branching phylogenetic tree with the living forms at the tips. And after being fed all this misinformation, the students are asked to form their own opinion! If they believe what Pandas has presented, they will have been thoroughly deceived.
Pandas tells us that we observe natural and manmade objects, resulting from two fundamentally different causes: natural and intelligent. But are not manmade objects created by natural means? And what about other "manufactured" objects, such as beaver dams and the nests of birds, wasps and termites and the honeycombs of bees? Certainly letters of the alphabet scratched in the sand were manmade but what about the letters of the alphabet hidden in the colored patterns of the wings of various butterflies? The Mount Rushmore monument is obviously of human origin but what about the face of George Bernard Shaw so clearly shown by the outline and relief of Pointe Bernard Shaw on Isle Radisson in Quebec? What about the regular geological formations photographed on Mars that look like the ruins of cities or others that resemble faces? We must be very careful if we are to correctly recognize evidence of intelligent beings elsewhere in the universe. But we and scientists are dealing with intelligent beings that work by natural means, not the supernatural beings that Pandas will try to introduce into the science classroom.
Teachers do have the right to present nonevolutionary views in their classrooms. But these are expected to be legitimate scientific views and the teacher has the responsibility to present reliable information and describe scientific concepts and theories accurately and correctly. No creationist work, including the present one, meets those basic requirements.
Although Pandas restricts itself to six subjects, they are certainly not treated in depth. One peculiar feature of the book's organization is that the footnotes to the material in the Excursion chapters are not printed in this book but are found only in the Teacher's Guide. A listing of these references will be given and they will receive further attention in the critiques on the Excursion chapters.
As I hope this work shows, Pandas is not a balanced and intellectually honest treatment. It is (for a creationist work) a low-key and skillful polemic against evolution.
White, A. D. 1960. A History of the Warfare of Science with Theology in Christendom. In two volumes. A reprint of the 1st edition originally published in 1896. Dover Publications.
Pandas' Suggested Reading And Footnotes
Pandas' bibliographic entries contain a large proportion of incomplete citations and a number of misspelled names. The listings given below contain the necessary corrections. Pandas' footnote references appear only in the Teacher's Guide.
None for Overview sections.
Excursion Chapter 1: The Origin Of Life
Thaxton, C. B., W. L. Bradley and R. L. Olsen. 1984. The Mystery of Life's Origins: Reassessing Current Theories. N. Y. Philosophical Library Publishers.
Shapiro, R. 1986. Origins: A Skeptic's Guide to the Creation of Life on Earth. London: W. Heinemann Ltd.
Excursion Chapter 2: Genetics And Evolution
Yockey, H. P. 1989. The Mathematical Foundations of Molecular Biology. N. Y. Cambridge University Press. (Note: I have not found this title in any of the library data bases available to me.—FJS)
Excursion Chapter 3: The Origin Of Species
Ambrose, E. J. 1982. The Nature and Origin of the Biological World. Chichester, West Sussex, England: Ellis Horwood Ltd.
Excursion Chapter 4: The Fossil Record
Lovtrup, Soren. 1987. Darwinism: The Refutation of a Myth. N. Y. Methuen.
Excursion Chapter 5: Homology
Augros, R. and G. Stanciu. 1987. The New Biology: Discovering the Wisdom in Nature. Boston. New Science Library of Shambhala Publications.
Excursion Chapter 6: Biochemical Similarities
Denton, M. 1986. Evolution: A Theory in Crisis. Bethesda: Adler and Adler.
Of Pandas and People: An Overview
Overview Section 1: The Origin Of Life
For centuries, the belief in spontaneous generation was considered to represent secondary creative acts of God. When the belief was finally laid to rest by the researches of Pasteur, all hopes of directly investigating the creation of living things by an intelligent being were dashed. But even as Pasteur was demonstrating that "full-blown" organisms did not arise de novo, he speculated on how life might have arisen gradually in stages from nonliving matter, foreshadowing the ideas of Oparin. According to today's view, the innate properties of matter and the deterministic laws of chemistry, under the proper conditions, would lead to the formation of living systems. Research in the field of prebiotic (chemical) evolution or biopoesis attempts to reconstruct the chemical steps and conditions leading to the origin of life.
Life In A Test Tube
Many experiments, attempting to simulate the conditions under which life arose, have been performed. Oparin's ideas and the experiment conducted by Miller were only the earliest attempts.
The researches of Fox have shown that polymerization of amino acids occurs readily by gentle heating and drying producing tiny cell-like proteinoid microspheres. Formation of RNA has also been accomplished in the laboratory. Although all these efforts have been given critical attention by scientists in the field and there are many unsolved problems, none of the criticisms mentioned by Pandas in the following sections have much validity.
Oxygen In The Air
Oxygen is a very reactive element. Free oxygen in the earth's atmosphere is a chemical anomaly explained by photosynthesis. Highly oxidized sediments, indicating an oxygen atmosphere, are almost a billion years younger than the oldest prokaryote fossils. Pandas' statements to the contrary are incorrect.
The direction in which a truly reversible reaction goes depends on the concentrations of reactants and products. If the products are removed by some other series of reactions, the first reaction will go in essentially one direction. Pandas' usage of the term "reversible" with respect to chemical reactions requiring large inputs of energy is incorrect. Many chemical processes used in industry require energy in some form, yet yield large amounts of product. Clearly, if Pandas' argument about energy making and destroying compounds is correct, we would never be able to make anything by adding energy! Of course there are traps in nature. For example, compounds synthesized by lightning would dissolve in rain drops and be washed down to the earth's surface where they would be safe from the next lightning flash, much as in Miller's apparatus.
Chemistry In 3-D
The restriction of biochemicals to specific three-dimensional forms would have arisen after the evolution of enzymes to catalyze reactions. Prior to the advent of biological enzymes, reactions might have been catalyzed by clay minerals which adsorb the reactants on their surfaces.
In actual experiments, the predominant outcome may be large yields of "goo" which has never been fully analysed so we don't know if it is non-biological or not. There is now some evidence that it is proteinaceous. And this material is found in meteorites and there is spectrographic evidence for it in the atmospheres of the outer planets and some of their moons. So some sort of chemical reactions, similar to those occurring in laboratory experiments, must have occurred in nature. Obviously not all the amino acids, etc. formed in these experiments are incorporated into this material. There are always a good deal left over in solution which can be analysed and identified.
The Language Of Life
Pandas says that all things result from two kinds of causes; natural and intelligent. Their classification implies that intelligence is unnatural! How do other "manufactured" items, such as beaver dams, and the nests of birds, wasps and termites fit into such a scheme? The analogy of the coded information in DNA to a message in a known language is highly exaggerated. The information is not organized into "words, phrases, and sentences." Even if scientists succeeded in determining the entire base sequence of an organism's genome, they would still be far from understanding how an organism results from that information. Because that information codes for many polymers of RNA and protein and the sequence in which they are to be synthesized so that their inherent self-organizing properties will "make" the organism. Also, molecular biologists have discovered that a large proportion of that "information" is nonfunctional nonsense.
When we find "John loves Mary" written in the sand, we assume that somebody scratched those letters there with a stick or with their fingers, because we have seen other people write similar messages in sand or mud. We probably have done it ourselves. People are part of nature, their bodies "obey" all the natural laws; they are a natural cause.
Observation clearly shows that DNA and protein (and new organisms) arise by various reproductive processes; changes in these materials and organisms have also been observed to arise by natural causes. In this regard, the theory of evolution follows the Principle of Uniformity. The same processes that we can observe producing organisms today and that we even use to modify organisms are those that acted in the past to produce the present day biological world. To say that this logically entails assuming that the "John loves Mary" message arose from the action of the waves is nonsense! All our observations on the reproduction of DNA and organisms indicate that Pandas' assertion that all information must be produced by "intelligence" is arbitrary and unwarranted. The idea that DNA originated from an "intelligent cause" is based on experience is nonsense. We have never seen an "intelligent agent" make DNA (other than biochemists in a laboratory). What would the agent look like? What would the phenomenon look like?
The idea of an "intelligent" agent producing life is not based on experience, but on a very weak analogy between organisms and manufactured objects that has been rejected by all modern philosophers beginning with Hume (author of the uniformity principle) in the 18th century. In fact this idea rejects the principle of uniformity, claiming that the "intelligent agent" only acted in the past and is not acting at the present time. At the present time, organisms come into existence by the entirely different phenomena of reproduction. Most "design proponents" (creationists) claim that the "intelligent agent" is a supernatural being, namely the Christian God, and that science is incapable of comprehending this creator and the creative process.
The hypothesis of biopoesis (the natural origin of life from nonliving matter) can be tested and serves as a guide for much fruitful research in biogeochemistry. Pandas (like all other creationists before them) makes no attempt to understand or investigate the nature of the "intelligent agent" but assumes that it is supernatural and beyond the realm of science. This is stated explicitly by Thaxton in the section at the end of the book entitled "A Word to the Teacher."
Overview Section 2: Genetics And Evolution
The short historical background that introduces this chapter is full of errors. Pandas' comments about Lamarck's views are incorrect. Body structures, etc. do respond to the organism's needs or habits. But these changes are not passed on to the organism's offspring, i.e. they are not heritable. As for Darwin, it was common knowledge that variation exists and occurs in species; animal breeders made use of it in producing new breeds. Mendel's laws of heredity do not explain how new traits are produced; only how existing traits are transmitted to offspring.
Pandas suggests that Mendel's work was antithetical to Darwin's and hence was "not taken seriously" until the twentieth century. Mendel was an ardent follower of Darwin's and considered his discoveries as the solution to the apparent problem of blending inheritance swamping out variations before they could be selected for. Few biologists were aware of his work, it being published in an obscure journal. Those who did read it were put off by its mathematical nature. Around 1900, his principles and his journal article were independently rediscovered by several geneticists. Pandas contradicts itself, now saying that Mendel's work was welcomed enthusiastically and integrated into evolutionary theory forming Neo-Darwinism.
In the final paragraph here, Pandas again seems unaware that neither blending inheritance nor Mendelian genetics address the question of the origin of new variants. On the other hand, blending inheritance would actively wipe out new variations, while Mendelian genetics results in a neutral stability preserving new variants (mutations), giving natural selection the opportunity to work with them. The stability that Mendel discovered is just what is needed for evolution to be possible!
Does Nature Select?
Pandas seems to think so. Of course natural selection can't foresee what is needed; it does not produce the new hereditary raw materials that it selects. Natural selection is differential survival and reproduction that tends to weed out the less fit and conserve the more fit. In doing so it definitely guides and determines the direction of evolution.
How Living Things Change
This section does not live up to its title, but introduces typical creationist concepts of horizontal versus vertical change and radically redefines evolution. To Darwin, evolution was descent with modification; to population geneticists, it is a change in gene frequencies. But here it is redefined as "the transformation of one type of organism into another." This definition of evolution is found in the creationist biology text, Biology, A Search for Order in Complexity, edited by J. N. Moore and H. S. Slusher, pp. 420, 431. But Pandas (as well as other creationists) refuse to give an operational definition of "type" or "kind". How can they say that breeders have never turned one kind of organism into another if they can't give us an operational criterion for distinguishing "kinds"? How can they tell if macroevolution has occurred or not?
New Patterns In Old Genes
Gene recombination is a tremendous source of variation. Pandas says that "if bred too far" (whatever that means) the animals become infertile and die out illustrating that there is a limit to how much animals can be changed. Research has shown that gene alleles for sterility may be closely linked on the chromosomes to the genes being actively selected and this brings about the sterility. If selection is relaxed for a few generations, crossing-over will decouple such alleles and selection can then continue without resulting in sterility. Eventually, however, one will exhaust the existing reservoir of variation and must wait upon mutations before further progress can be made.
Mutations: Mistakes In The Genetic Message
Most mutations result from copy errors during reproduction of the genetic material. Although Pandas says that mutations do not create new structures, but merely alter existing ones, that's the stuff that makes evolution! For the most part, vertebrates (and other groups of organisms) are distinguished from one another by the changes in structures that they all possess. Pandas claims that for all the altered structures produced by mutations in "The fruit fly" they have not created a new kind of wing or a new kind of insect. Again, what would constitute a new kind of wing or insect? Pandas claims that virtually all mutations are harmful. Actually most mutations are neutral, many of those producing small changes are beneficial, only most of those producing large, easily detected changes are harmful. In a way, mutations are akin to typing errors, but the analogy easily can be pressed too far.
It is Pandas' opinion that all the changes observed in the lab or breeding pen represent microevolution. Previously Pandas stated (p. 9) that breeders have produced differences greater than those between natural species. Many evolutionists would consider those macroevolutionary changes. Virtually all evolutionists today believe that macroevolution is compatible with microevolutionary processes. None of the new suggestions (such as punctuated equilibrium) require a new genetic theory to explain macroevolution.
Intelligent Design: Package Deal
Giraffes are browsers feeding on leaves of trees and shrubs. They normally do not graze on grass. Interestingly enough the photograph of a giraffe drinking (p. 12) clearly shows that a giraffe's neck is not long enough to reach the ground. The giraffe must assume a very awkward posture of spreading and/or bending its front legs in order to reach the ground! In certain parts of Africa where the foliage is sufficiently succulent, giraffes rarely, if ever, drink water.
Contrary to Pandas' statements, there is nothing very special about the giraffe's circulatory system. It does have a much higher blood pressure than most other animals, but all other the other hoofed mammals with "normal-sized" necks have the same system of blood pressure controls. There is no danger of the blood vessels in the lowered head of the giraffe bursting any more than at the bottom of its long legs, the increased pressure in the extracellular fluids of the giraffe's tissues exactly counteracts the increased blood pressure. All of the features of this "adaptational package" are found in other mammals, including the short-necked relative of the giraffe, the okapi. Thus the problem posed by Pandas, of all the adaptations occurring simultaneously, is a pseudoproblem. All the elements of the overall integrated package are shared by present day mammals and undoubtedly were present in the giraffe ancestor.
Pandas' calculation of how likely it is that random mutations will come together and coordinate to form a new structure is based on the assumption that all of the necessary mutations occur simultaneously in the same individual. The evolutionary mechanism has four main components: mutation, reproduction, genetic recombination and natural selection. Pandas is ignoring the last three components. Also evolution most often proceeds, not by producing truly new structures, but by modifying old ones. Mutations producing beneficial modifications may occur in various individuals, where reproduction and natural selection will cause them to spread through the population in the course of succeeding generations and genetic recombination will eventually bring them together in many individuals. Computer simulations have shown that if such mutations occur, their eventual combination together is virtually a certainty. Pandas' calculation is totally irrelevant because it is based on wrong assumptions about the nature of the evolutionary mechanism.
Again Pandas' analogy about the plumber and electrician is irrelevant. The giraffe does not have a "new" body plan. Its body plan is a typically mammalian one, only certain parts have been modified as to their size and shape.
One could build a palace by tinkering with a tool shed and adding bits and pieces here and there. It probably wouldn't look like the usual palace but it might serve the functional purpose just as well. And the biological evidence shows conclusively that the "higher" vertebrates evolved through modification and tinkering with a developmental system that originally produced fishes. For example, many of the structures in the head and neck of terrestrial vertebrates are modified from a set of gill pouches, arches and bars that are produced in the early embryo. In truth, the palace did originate in bits of marble added to the tool shed! The intelligent design view, what there is of it, does not fit the facts. Pandas "evidence" against evolution is couched in terms of a creationist definition of evolution and the undefined terms "kind" and "type".
Overview Section 3: The Origin Of Species
Again Pandas claims that there are limits to variation within existing groups of plants and animals but still refuses to suggest what those limits are and what "groups" are. Are the existing groups which define the boundaries of variation species? genera? families? The variation in dogs is equivalent to that found in some "natural" genera. The variation in the Hawaiian honey creepers is equivalent to that distinguishing other families of birds.
Species are characterized by their reproductive isolation from other species. The degree of visible difference between closely related species may be quite considerable or it may be virtually nonexistent. There are many different mechanisms of reproductive isolation besides the geographic and ecological mechanisms mentioned here. Also, all degrees of reproductive isolation are found in nature; it is not an all-or-none phenomenon.
Physical Barrier, The Break-Up Of A Breeding Chain
Reproductive isolation, initiated by geographic barriers is called allopatric speciation and is considered to be the almost universal mechanism that produces new species. Many well-known cases of "breeding chains" are known in various groups of birds, amphibians and butterflies.
Pandas is very naive in speaking of the North American fruit fly, as if there were only one! The hawthorn and apple fruit flies mentioned in this section belong to the family Tephritidae which includes 290 North American species! Tephritid larvae infest and feed on fresh fruits and hence may become economic pests in contrast to the Drosophilidae (190 North American species) which attack decaying fruit. Tephritid flies are about the size of house flies whereas drosophilids are much smaller. The importance and commonness of reproductive isolation resulting from ecological isolation is controversial, although the phenomenon has been produced in the laboratory using Drosophila in population cages.
Genetic Drift, The Founder Effect, The Bottleneck Effect
These mechanisms produce changes in genetic information, not necessarily losses in genetic information. No genes are lost. There are changes in the proportions of the alleles of various genes and some of the alleles might be lost, but this variation is replenished by subsequent mutations.
Is Speciation Evolution?
There is no question that speciation is evolution. This is a fictitious problem created by Pandas. But what is evolution? Again, to Darwin, evolution was "descent with modification"; to population geneticists, it is "a change in gene frequencies." Pandas insists on a new definition. Change is no longer enough. "New" genetic information must be introduced producing "new" levels of complexity. Pandas doesn't tell us whether mutations that produce new versions of a gene are sufficient or whether the production of new, additional genes (which usually occurs by mutation of duplicate copies of an existing gene) is necessary to meet their new criterion.
Pandas claims that speciation is microevolution. Many biologist, especially those favoring punctuated equilibrium, consider it macroevolution. According to Pandas, microevolution doesn't add new levels of complexity. By Pandas' definition, it isn't even evolution! It only produces "horizontal diversification." The evolution of the many orders of mammals or of insects was brought about mainly by changes in structures, rather than the production of truly "new" structures. Are these great adaptive radiations of forms only "microevolution"? If a geneticist transformed a fruit fly into a beetle, would this be evolution? Are beetles more complex than flies? To a lesser extent, the evolution of mammals from reptiles involved similar changes in old structures. The wings of birds are modified front limbs and feathers are modified scales. Are all these evolutionary changes to be considered microevolution—a kind of nonevolutionary diversification? If this is so, is Pandas willing to admit that such extensive changes in biological form are possible by natural means?
Yes, speciation is very much like what breeders do. Centuries of breeding have produced a great deal of change. The various breeds of dogs exhibit variation that in nature would be sufficient not only to define new species but even genera. This is quite remarkable, considering the very small populations that breeders work with, which precludes the likelihood of many mutations augmenting the genetic variation available for selection. The variation in the Hawaiian honeycreepers mentioned at the beginning of this overview section display variation equivalent to genera, families and even possibly orders among other birds.
Overview Section 4: The Fossil Record
The Cambrian Explosion
Only a small fraction of the known phyla have any fossil record, thus Pandas' statement that virtually all of them appear at about the same time in the fossil record (at the beginning of the Cambrian period) is not based on evidence. Even those few that are represented in the fossil record, appear at different times, before, during and after the Cambrian.
Gaps In The Fossil Record
There are transition series of fossils leading from fish to amphibians, amphibians to reptiles and from reptiles to birds and mammals, in some instances making it difficult to discern the boundaries of the classes. This is especially true of the amphibian-reptile and reptile-mammal transitions. Archaeopteryx has all the skeletal features of a theropod dinosaur and is often classified with them in the modern literature. Yet it had feathers and primitive wings revealing its relationship to the birds.
Fish do not have all the characteristics of true fish from the earliest known fossils. The earliest fossils lack jaws, paired limbs and bony internal skeletons. The earliest amphibians had many of the characteristics of fishes. Usually fossils only provide knowledge of skeletal anatomy, so we don't know if the earliest reptiles had all the characteristics of "true" reptiles, but their skeletons are hardly distinguishable from those of the amphibians of their day. And there is a large series of reptiles, the synapsids, who over time gradually acquired more and more mammalian characteristics, eventually resulting in "true" mammals.
Pandas seems to have gotten this argument backwards. All the palaeontologists who emphasize stasis apply it to the species! In the course of geological time, the species composition of the higher taxa change, so those taxa definitely do not exhibit stasis.
Darwin: The "Gravest Objection Against My Theory"
It is unreasonable to expect to find long continuous chains of transition forms in the fossil record. Consider the evolution of the modern horse from eohippus, which occurred over a period of 60 million years. If we assume a generation time of three years, that corresponds to 20 million generations. Let us further assume that it takes 1 foot of sediment to bury a horse (probably not enough for the larger, more recent horses, but more than enough for the dog-sized early ancestors, so 1 foot is a reasonable average). To get a really complete series of transitional forms, we would require at least 1 specimen from each generation. But, if every three years, a river flood buries one horse or horse ancestor under 1 foot of sediment, that eventually amounts to 20 million feet of sediment! Which translates into 3,788 miles, a figure almost equal to the radius of the earth! The total thickness of the Tertiary sediments in western North America that contain the fossil equid sequence is a bit under 10,000 feet. Thus only a tiny fraction of a complete transitional series could have been preserved. Yet, the known fossil horses provide a fairly continuous record with only one or two small gaps.
Obviously the transition series that we have in the fossil record are not 100% complete. Many gaps still remain. But remember, whenever another transition form is found, it divides a gap into two smaller ones! As long as the fossil record remains incomplete the number of gaps will not decrease! The fossil record is like a motion picture sequence which is made up of a series of still frames, each one representing a small change in the picture and the whole series of them representing a transition sequence between the scene at the start and at the end of the series. Yet there is a short time "gap" between the frames. The frames represent fossil species, forming the transition sequences which are known in the fossil record. Transitions between species (the gaps between motion picture frames) are much rarer, but examples of those also are known.
Archaeopteryx is an intermediate form between reptiles and birds that fulfills the evolutionary prediction of transition forms between those two classes. Why should intelligent designers produce such a form? (Here it is considered an "odd-ball" type, but in Excursion chapter 4, it is considered a "true" bird.) The leathery bill of the platypus is only superficially like the bill of a duck. Its skeleton and organ systems are a mixture of mammalian and reptilian features. Some biologists consider that it is more closely related to the mammal-like reptiles than the true mammals.
Fossils do form graded series! Living species of horses form a cluster separated from the living species of tapirs. But when one considers the fossil forms, there are known graded series leading back from each set of living forms and converging on a common ancestor in the Eocene period.
Evolution By Leaps
The main principle of Darwin's theory is evolution guided by natural selection. No evolutionists reject this. Punctuated equilibrium is only a minor modification of Darwinian evolution. It assumes that species (not taxa in general) remain relatively stable and that most evolutionary changes occur during speciation, which takes anywhere from 5,000 to 100,000 years (not hundreds of years). The changes that occur at speciation come about by conventional microevolutionary mechanisms. Because the transitional forms are restricted in time and space, they are unlikely to be found in the fossil record.
Taking The Rocks At Face Value
Punctuated equilibrium is not based entirely on negative evidence. Fossil examples of transitions between species are known and these are restricted in space and time relative to the occurrence of the species themselves just as the hypothesis predicts.
If design theory requires that various forms began abruptly with their various features intact, then it is wrong. The first fishes lacked jaws, paired limbs and bony internal skeletons. Birds first appeared with feathers and primitive wings but not with any of the skeletal specializations of modern birds. Did mammals first appear with fur and mammary glands? Those features don't fossilize. Indirect evidence would indicate that some mammal-like reptiles had them but again these forms did not possess all the mammalian specializations of the skeleton and reproductive systems. Of course, creationists could backpedal on these predictions and say that the designer(s) experimented with many versions before they got the designs just right.
We are given the evolutionary interpretation of the fossil record and if we pay homage to the principle of uniformity the organisms of more recent times must be the descendants of those of earlier times. Remember Pasteur proved that life only comes from life.
But just what is the "intelligent cause" interpretation? Very little is said about it because it could prove to be very embarrassing. Some creationists believe that the world is very old and others believe that it is no older than a few thousand years and that all (or some combination) of the geological strata are the result of a worldwide flood. There is hardly any common ground between those two views.
But let's take the fossil record at face value. If fossils are lacking, it's because such forms never existed. Fossil species come and go. The designers kept making more and more new designs with the passage of geologic time. And they apparently kept on eliminating old designs just as fast. At the beginning of the Paleozoic era they must have been trying out new designs for phyla at a furious pace. And apparently they changed their minds many times. Most taxa do not have continuous fossil records. We must conclude that the designers wiped them all out and then at a later time reinvented them. The coelacanths are a nice example. The designers wiped them out in the Cretaceous and then, for what reason, recreated them in the form of the present day genus Latimeria.
Fact Versus Interpretation
The fossil record does establish evolution as a fact, because as Pandas has shown, the intelligent design proponents (creationists) cannot come up with a reasonable alternative. Naturally, all organisms that lived long enough and survived to form fossils would be fully-formed! Any partially-formed ones would not be viable. But an animal can be fully-formed and yet not have all the features characteristic of its group. The platypus and Archaeopteryx are excellent examples of this.
Evolution is a scientific theory; it offers detailed testable mechanisms. Intelligent design is not because it does not offer detailed testable mechanisms. The designer(s) are vague shadowy concepts providing no real understanding of the phenomena of the living world.
Overview Section 5: Homology
Mary Had A Little Lamb (Ovis Aries)(Sic)
As Pandas says, living things do fall into a neat group-within-group arrangement. Yet Pandas directly contradicts this statement later in the chapter, by using vague terms such as "patchwork pattern", "contradictory similarities" and "living mosaic"! The common body plan of vertebrates involves the anatomical features of all their organ systems, not just the skeletal system as the overly simplified Figure 6 implies. The pattern of similarity is augmented by the data from the fossil record, from which palaeontologists have been able to trace lines of descent connecting the present day living groups.
Birds and fish have very much more in common than feathers and scales respectively. The only problems with classifying vertebrates into the various classes occurs with the transition fossils (mentioned in the previous section) that bridge the gaps between those classes.
Certain marsupials and placentals are superficially similar. The only thing flying squirrels and flying phalangers have in common is that they are small mammals with long tails and flaps of skin forming gliding membranes. In skeletal structure the North American wolf and now-extinct Tasmanian wolf are clearly distinctive. If found as fossils, they would never be counted as members of the same species! Palaeontologists have no trouble distinguishing marsupial and placental fossils from one another. The two "wolves" differ in many ways in addition to their different modes of reproduction. The same holds true for the other marsupial-placental "look-alikes", they are similar in some of their ecological adaptations, but the marsupials all share basic skeletal, dental, reproductive, neurological, behavioral, developmental and other features. Even the 19th century pre-evolutionary anatomists recognized the distinction between marsupials and placentals.
Function Versus Structure
Although Linnaeus based his classification on structure, the terms homology and analogy were not invented by him, but by the 19th century British anatomist, Richard Owen. Homologous bones for example, are the corresponding parts in various animals, with the same relationships to the adjacent bones, corresponding muscles, blood vessels, nerves, and with a corresponding similar developmental origin, etc. This is how homologous structures were identified by both the pre-evolutionary and the evolutionary biologists. The more details that are identical in a specific structure in a variety of forms, the more likely it represents a homology—part of the basic archetype (in the philosophy of pre-evolutionary anatomy) or derived from a common ancestor (in evolutionary theory). Analogous structures always exhibit differences in the details of their structure; their similarities are usually the result of functional constraints. There is one best streamlined shape for a fast swimming aquatic organism, all limbs for digging will have shovel-like shape; all wings must meet certain rigid aerodynamic requirements, etc. Difficulties in sorting out homologies and analogies occur in closely related organisms in structures which are a mixture of homology and analogy.
Pandas, which has greatly exaggerated the similarities of the placental and marsupial "wolves" should give illustrations of those "structures of astonishing similarity at first regarded as homologous . . . later determined to be analogous."
The Puzzling Panda
The present day view is that the giant Panda is a bear and the red panda a racoon, but it must be remembered that bears and racoons themselves are closely related. That, along with the fact that the two pandas are adapted to similar habitats, made the analogies and homologies hard to sort out. But the newest biochemical data have settled the question. Also, detailed comparison of the chromosome structures of the two pandas indicates that the giant panda is related to the bears and the red panda to the racoons. Pandas is wrong in this regard. Pandas is also wrong in gracing the red panda with a "panda's thumb." Furthermore, Pandas' view that living things are like collections of pre-assembled units would predict that the intelligent designer would have endowed pandas with a true opposable first finger and not with this rather crude "fake" thumb unique to the Giant Panda. This is more like a case of natural selection making do with materials at hand (like a tinkerer) to assist the panda to strip leaves from the bamboo.
It is one of the central problems of taxonomy to distinguish between analogies and homologies. This was just as true for the pre-evolutionary 18th and early 19th century taxonomists as it is for the evolutionary taxonomists. As we have already mentioned the criterion for homology is the degree of detail to which similar structures correspond in different organisms, not only in their own structure but in their relations to associated parts and in their development. This same criterion was used by the 19th century pre-evolutionary biologists as well as their evolutionary successors. Obviously this criterion is independent of evolution. Thus citing homologous structures as evidence of evolution is not circular reasoning.
The Products Of Design
Prior to the great voyages of exploration beginning in the 15th century and the invention of the microscope in the 17th, scholars had very limited knowledge of the diversity of living things. Biological classification was only a casual activity until the eighteenth century when it was taken up in earnest as a biological discipline. The concept of types and archetypes was an arbitrary philosophical scheme, quite different from the biblical idea of special creation. True, many things can be classified that are not derived from a common ancestor, but then they are not always arrayed into hierarchical classifications. What makes "all Fords look similar" is not the "pattern in the mind of the person making them" but the collective input of the activity of a team of engineers that may number as many as 12,000. Making human designers as the basic analogy would not suggest a single "primeval"(?) intellect but many teams, each consisting of a large number of designers. As for piggybacking on existing patterns, the earliest automobiles did resemble the horse-drawn carriages of their day, but the parts of modern automobiles are totally different, with no traces of the horse-drawn carriage in them; and NASA's Apollo spacecraft and the Space shuttle were, in fact, designed from scratch! In contrast, mammals (including humans), retain many marks of their fish ancestry.
A Living Mosaic
The "puzzle of the marsupials" is again misrepresented. It was not patterns for wolves, cats, squirrels, etc. that evolved twice, but more general patterns for cursorial predators, stalking predators, herbivores, burrowers, etc. that evolved. There are only superficial resemblances between the ecological homologues among the marsupials and placentals. This was accomplished not by mutation along but by mutation guided by natural selection producing similar (but not identical) features adapted to similar ecological ways of life.
Flight did evolve four times. The flight adaptations in the four groups mentioned differ in many important respects, especially when one compares the insects and the vertebrates. If one intelligent designer is responsible for them all, why aren't the flight adaptations identical? And why should there be four different flying groups to begin with? Four types of airplane, exhibiting design features as different as those in the four groups of flying organisms would only have been produced by four different, independent designers (or rather, teams of design engineers). Clinging to the designer analogy, is Pandas suggesting that different teams of intelligent designers are responsible for these flying organisms?
Taken all together, all the similarities and differences do trace a branching pattern indicating evolutionary descent. It is important to note that the basic classification used today was established by pre-evolutionary biologists. Any superficially ecological adaptations are clearly derived from the more basic structures shared by members of the different groups and do not represent a pattern of fixed patterns of discrete blocks. If this were so, we would expect all flying organisms to have identically constructed wings, or identical sets of carnassial teeth, etc. Hemoglobin would appear to be such a fixed pattern or discrete block but it clearly evolved independently from myoglobins which are universally found in eukaryote organisms.
In the following section, the protein cytochrome c, a perfect biological example of a pre-assembled unit "that can be plugged into a complex electronics circuit", is considered. The intelligent design hypothesis predicts that it should be identical in all forms yet it exhibits a pattern of structural variation that definitely supports evolution.
Overview Section 6: Biochemical Similarities
Homology Writ Small
Certainly the biochemical data on the amino acid sequences of related proteins provides a great many more homologies upon which to base classification. And the biochemical classifications confirm those produced by traditional methods, indicating that the earlier taxonomists did a good job of sorting out homologies from analogies. Pandas doesn't mention it, but the biochemical classification supports the distinction between the marsupials and the placental mammals. Pandas tried to express some vague dissatisfaction with that classification in the previous section.
The new findings of biochemistry are important new evidence for evolution and against creation (or intelligent design)! As we shall see with the example of cytochrome c, the intelligent design hypothesis cannot explain the results.
This is in total contrast to what Pandas says. But cytochrome c does not illustrate Pandas' principle that similarity in structure reflects similarity in function! And why did the intelligent designers create an ecological web and food chains? There is no corresponding phenomena among human manufactured products! Predators and prey are somewhat analogous to weapons and counter-weapons, which are usually conceived and designed by different and antagonistic teams of designers. Are we to assume the same is true for the designers of organisms? But since Pandas asserts that intelligent designers did this, and made all organisms out of the same basic substances so that the food chain would work, why did they make plants out of cellulose and lignins and then forget to endow the herbivores with enzymes to digest those materials?
A New Pattern
Pandas demonstrates that the data in Table 1, taken column-wise corroborates traditional taxonomic categories. The hierarchic classification of organisms supports the evolutionary idea that those categories inherited their common features from common ancestors.
But the data, taken row-wise is supposed to refute evolution! This argument is based on Pandas' illogical and irrational assumptions. They arrange the animals listed in the table into an evolutionary ladder, which implies, among other things, that the present day humans evolved from the present day Rhesus monkey; that the horse evolved from the rabbit; that the dogfish evolves from the silkworm moth which in turn evolved from wheat! Nothing could be more wrong and idiotic! Evolution doesn't produce a single linear series, especially of present day living forms, but a branching phylogenetic tree, of which the living forms represent the tips of the branches. All the eukaryote organisms differ from the bacterium by the same percentage because they are all equidistant in time from their common ancestor with the bacterium.
Similarly certain fish evolved into amphibians, but the organisms involved were Devonian crossopterygian fishes that produced amphibians like Ichthyostega. If the cytochrome c proteins of those long extinct forms were available, we would expect them to be very similar. But not the cytochrome c proteins of the present day carp and bullfrog! None of the present day living forms represent intermediate forms between the various vertebrate classes. The similarities in cytochrome c of the various taxonomic groups are explained by evolution as due to the recentness in time of their common ancestors.
But why are the cytochrome c proteins different? Cytochrome c performs exactly the same function under the same physiological conditions (inside the mitochondria) of all the organisms considered (except the bacterium, which don't have mitochondria). Over geologic time, random neutral mutations have produced amino acid substitutions in cytochrome c which did not change or affect its functioning in any way. Some of these mutations became fixed in their populations and were passed on to the species that evolved from them. The molecular clock does not assume a uniform rate of mutation, only a long-term average rate of fixation of neutral mutations. Thus Pandas' argument about mutation rates being related to reproduction rates is irrelevant. That argument is also erroneous; mutation rates may be related to generation time. The fact that different proteins seems to have molecular clocks running at different rates is to be expected. Some proteins have more rigorous functional constraints on their amino acid constituents than others, thus there will be fewer possible neutral mutations in those proteins.
If the differences in cytochrome c are due to accumulation of random, neutral mutations, then the similarities in cytochrome c structure that say, all vertebrates share with insects, plants and bacteria, can only be explained by common ancestry! That makes these data direct evidence for evolution and not just another criterion for classifying organisms.
Creationists Can't Explain These Data!
It has been conclusively proven that cytochrome c is an enzyme performing an identical function in all the organisms considered and is a perfect example of a "pre-assembled" unit that Pandas refers to at the end of the preceding section. Thus if all these forms were created by an intelligent, rational designer, cytochrome c should have an identical structure in all these forms. But it doesn't! So why is this enzyme different in the various classes?
Even if creationists fall back upon a molecular clock model (the clock running about a million times faster than the evolutionists postulate), the expected results would be different. Because all these forms would be equidistant in time from their creation, they all should be equally different from one another (say 65% different). Thus the creationist is almost forced to assume that these differences in cytochrome c structure are somehow adaptive (i.e. functionally significant) in the various forms. But all the biochemical evidence points to the fact that the observed differences in amino acid sequence are neutral and have no effect on the function of cytochrome c. That in fact is what makes the molecular clock plausible. Thus the creationists must present some specific explanations as to the function of these structural differences in cytochrome c. Even if they succeed in doing so, they still have to explain why the sequencing data from other proteins (and DNA and RNA) all produce the same hierarchical groupings. The results of DNA, RNA and protein sequencing provide some of the most significant evidence against creation (or intelligent design) and for evolution.
The Task Of Taxonomy
In a superficial way contemporary organisms might appear to fit a theory of intelligent design (although Pandas does not offer one with any detail, only some vague undefined generality.) But the fossil record does reveal the transitional forms and connecting links between the various taxa. Pandas' denial of this fact, based on a tremendous amount of evidence, is simply false. Palaeontologists are not abandoning Darwinism for some new theory of sudden change. This is a gross misinterpretation of punctuated equilibrium. Although many fossil species are separated by gaps, the sequences of the species themselves represent transitional stages. No palaeontologists deny this.
The biochemical data clearly can only be explained by evolution. Pandas' argument against this is based on the false premise that living organisms must be lined up in a true evolutionary series or ladder.
All the data from a variety of fields come together like pieces in a jigsaw puzzle that supports evolution. No creationist has ever been able to make such a synthesis to support creationism. Certainly Pandas does not do it.
(from Frank Sonleitner's critique of Of Pandas and People)