A Critique of the Theory of Evolution

CHAPTER I. A Revaluation of the Evidence on

A REVALUATION OF THE EVIDENCE ON WHICH THE THEORY OF EVOLUTION WAS BASED

PAGE PREFACE v

1. THREE KINDS OF EVOLUTION 1-7

2. THE EVIDENCE FOR ORGANIC EVOLUTION 7-27 a. The Evidence from Comparative Anatomy 7-14 b. The Evidence from Embryology 14-23 c. The Evidence from Paleontology 24-27

3. THE FOUR GREAT HISTORICAL SPECULATIONS 27-39 a. The Environment 27-31 Geoffroy St. Hilaire b. Use and Disuse 31-34 From Lamarck to Weismann c. The Unfolding Principle 34-36 Nägeli and Bateson d. Natural Selection 36-39 Darwin

CHAPTER II. The Bearing of Mendel's Discovery on

THE BEARING OF MENDEL'S DISCOVERY ON THE ORIGIN OF HEREDITY CHARACTERS

1. Mendel's First Discovery--Segregation 41-52

2. Mendel's Second Discovery--Independent Assortment 52-59

3. The Characters of Wild Animals and Plants Follow the Same Laws of Inheritance as do the Characters of Domesticated Animals and Plants 59-84 a. Sexual Dimorphism 61-64 Eosin eye color of Drosophila 61-62 Color of the Clover Butterfly, Colias philodice 62-63 Color of Papilio turnus 63 Color pattern of Papilio polytes 63-64 b. Duplication of parts 65-66 Thorax of Drosophila 65 Legs of Drosophila 65-66 c. Loss of characters 66-68 "Eyeless" of Drosophila 66-67 Vestigial wings of Drosophila 67 Bar eye of Drosophila 67-68 d. Small changes of characters 68-70 "Speck" 68 Bristles of "club" 70 e. Manifold effects of same factor 71 f. Constant but trivial effects may be the product of factors having other vital aspect 73 g. Sex-linked inheritance 75-80 in Drosophila ampelophila 75-76 in the wild species D. repleta 76 in man 77 in domesticated Fowls 77-78 in the wild moth, Abraxas 78-80 h. Multiple allelomorphs 81-84 in the wild Grouse Locust 81-83 in domesticated mice and rabbits 83 in Drosophila ampelophila 84

4. MUTATION AND EVOLUTION 84-88

CHAPTER III. The Factorial Theory of Heredity

THE FACTORIAL THEORY OF HEREDITY AND THE COMPOSITION OF THE GERM PLASM

1. THE CELLULAR BASIS OF ORGANIC EVOLUTION AND HEREDITY 89-98

2. THE MECHANISM OF MENDELIAN HEREDITY DISCOVERED IN THE BEHAVIOR OF THE CHROMOSOMES 98-102

3. THE FOUR GREAT LINKAGE GROUPS OF DROSOPHILA AMPELOPHILA 103-118 a. Group I. 104-109 b. Group II. 109-112 c. Group III. 112-115 d. Group IV. 115-118

4. LOCALIZATION OF FACTORS IN THE CHROMOSOMES 118-142 a. The Evidence from Sex Linked Inheritance 118-137 b. The Evidence from Interference 137-138 c. The Evidence from Non-Disjunction 139-142

5. HOW MANY GENETIC FACTORS ARE THERE IN THE GERM-PLASM OF A SINGLE INDIVIDUAL? 142-143

6. CONCLUSIONS 144

CHAPTER IV. Selection and Evolution

SELECTION AND EVOLUTION

1. THE THEORY OF NATURAL SELECTION 145-161

2. HOW HAS SELECTION IN DOMESTICATED ANIMALS AND PLANTS BROUGHT ABOUT ITS RESULTS? 161-165

3. ARE FACTORS CHANGED THROUGH SELECTION? 165-187

4. HOW DOES NATURAL SELECTION INFLUENCE THE COURSE OF EVOLUTION? 187-193

5. CONCLUSIONS 193-194

INDEX 195-197

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CHAPTER I

A REVALUATION OF THE EVIDENCE ON WHICH THE THEORY OF EVOLUTION WAS BASED

We use the word evolution in many ways--to include many different kinds of changes. There is hardly any other scientific term that is used so carelessly--to imply so much, to mean so little.

THREE KINDS OF EVOLUTION

We speak of the evolution of the stars, of the evolution of the horse, of the evolution of the steam engine, as though they were all part of the same process. What have they in common? Only this, that each concerns itself with the history of something. When the astronomer thinks of the evolution of the earth, the moon, the sun and the stars, he has a picture of diffuse matter that has slowly condensed. With condensation came heat; with heat, action and reaction within the mass until the chemical substances that we know today were produced. This is the nebular hypothesis of the astronomer. The astronomer explains, or tries to explain, how this evolution took place, by an appeal to the physical processes that have been worked out in the laboratory, processes which he thinks have existed through all the eons during which this evolution was going on and which were its immediate causes.

When the biologist thinks of the evolution of animals and plants, a different picture presents itself. He thinks of series of animals that have lived in the past, whose bones (fig. 1) and shells have been preserved in the rocks. He thinks of these animals as having in the past given birth, through an unbroken succession of individuals, to the living inhabitants of the earth today. He thinks that the old, simpler types of the past have in part changed over into the more complex forms of today.

He is thinking as the historian thinks, but he sometimes gets confused and thinks that he is explaining evolution when he is only describing it.

A third kind of evolution is one for which man himself is responsible, in the sense that he has brought it about, often with a definite end in view.

His mind has worked slowly from stage to stage. We can often trace the history of the stages through which his psychic processes have passed. The evolution of the steam-boat, the steam engine, paintings, clothing, instruments of agriculture, of manufacture, or of warfare (fig. 2) illustrates the history of human progress. There is an obvious and striking similarity between the evolution of man's inventions and the evolution of the shells of molluscs and of the bones of mammals, yet in neither case does a knowledge of the order in which these things arose explain them. If we appeal to the psychologist he will probably tell us that human inventions are either the result of happy accidents, that have led to an unforeseen, but discovered use; or else the use of the invention was foreseen. It is to the latter process more especially that the idea of purpose is applied. When we come to review the four great lines of evolutionary thought we shall see that this human idea of purpose recurs in many forms, suggesting that man has often tried to explain how organic evolution has taken place by an appeal to the method which he believes he makes use of himself in the inorganic world.

What has the evolution of the stars, of the horse and of human inventions in common? Only this, that in each case from a simple beginning through a series of changes something more complex, or at least different, has come into being. To lump all these kinds of changes into one and call them evolution is no more than asserting that you believe in consecutive series of events (which is history) causally connected (which is science); that is, that you believe in history and that you believe in science. But let us not forget that we may have complete faith in both without thereby offering any explanation of either. It is the business of science to find out specifically what kinds of events were involved when the stars evolved in the sky, when the horse evolved on the earth, and the steam engine was evolved from the mind of man.

Is it not rather an empty generalization to say that any kind of change is a process of evolution? At most it means little more than that you want to intimate that miraculous intervention is not necessary to account for such kinds of histories.

We are concerned here more particularly with the biologists' ideas of evolution. My intention is to review the evidence on which the old theory rested its case, in the light of some of the newer evidence of recent years.

Four great branches of study have furnished the evidence of organic evolution. They are:

Comparative anatomy. Embryology. Paleontology. Experimental Breeding or Genetics.

The Evidence from Comparative Anatomy

When we study animals and plants we find that they can be arranged in groups according to their resemblances. This is the basis of comparative anatomy, which is only an accurate study of facts that are superficially obvious to everyone.

The groups are based not on a single difference, but on a very large number of resemblances. Let us take for example the group of vertebrates.

The hand and the arm of man are similar to the hand and arm of the ape. We find the same plan in the forefoot of the rat, the elephant, the horse and the opossum. We can identify the same parts in the forefoot of the lizard, the frog (fig. 3), and even, though less certainly, in the pectoral fins of fishes. Comparison does not end here. We find similarities in the skull and back bones of these same animals; in the brain; in the digestive system; in the heart and blood vessels; in the muscles.

Each of these systems is very complex, but the same general arrangement is found in all. Anyone familiar with the evidence will, I think, probably reach the conclusion either that these animals have been created on some preconceived plan, or else that they have some other bond that unites them; for we find it difficult to believe that such complex, yet similar things could have arisen independently. But we try to convince our students of the truth of the theory of evolution not so much by calling their attention to this relation as by tracing each organ from a simple to a complex structure.

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