THE SCIENTIFIC MONTHLY AUGUST. 1922 THE GEOLOGIC EVIDENCE OF EVOLUTION ONE By Professor EDWARD W. BERRY THE JOHNS HOPKINS UNIVERSITY NE of the outstanding, possibly the only difference between man and the other animals is his ability to profit by the experience and accumulated wisdom of the race, and yet, despite this characteristic, each generation seems to produce its quota of antivaccinationists, anti-evolutionists and believers in a flat earth. We may still entertain the hope that the race is becoming more rational when we recall that it has taken about three centuries to convince the Anglo-Saxon and a few other races among the countless millions of the globe that the earth is not flat, so that to-day only the leader of Zion City (Voliva) among leading cosmologists defends the pentateuchal view. I do not wish to be thought of as sneering at any one's beliefs, and I fully realize that there are a great many earnest Christian men and women who are perturbed at anything that they think, rightly or wrongly, will shake the foundations of their faith, who are puzzled by the present outspoken opposition to evolution, and who wish to know what is the truth. No truer article of faith was ever penned than the motto of the Johns Hopkins UniversityVeritas vos liberabit-and to you seekers after truth I would like to explain away certain misconceptions, before undertaking to show you that the record of earth history is the record of evolution, and not to be disputed by honest people. Evolution is not a theory of origins, nor an article of scientific faith, but an indisputable fact. We could not teach geology without teaching evolution. One of the difficulties to the layman is the confusion of evolution-the record of the past and present history of organisms-with the various theories that have been proposed to explain its factors or mode of operation. Let me emphasize that evolution, the record, is in an altogether different category from the theories such as Darwinism, Lamarckianism, or any other VOL. XV-7 ism that has been advanced to explain its working. You may flout all the theories or you may advocate one of a dozen different theories, but this has nothing to do with the history of life. We, in geology, spend much time in going over the history of organisms, but pay but slight attention to the theories-at least in our teaching. A simple illustration of the once universal and now fortunately less frequent clerical reaction to evolution will make clear what I am driving at. Evolution was regarded as a dangerous heresy, inimical to Christianity, contrary to Genesis, which was regarded as a scientific account of the origin of the earth and its inhabitants. Do these people claim that the hundreds of varieties of horses, dogs, chickens and pigeons go back to the Garden of Eden, or were in Noah's ark, or that all the horticultural varieties of flowers, shrubs and vegetables were in Mother Eve's kitchen garden? Not at all! They are more or less familiar with the cattle breeders or the Burbank method of artificial selection. Their objection to evolution rests on the assumption that man is of a different stuff from the brute world-as if they had had no experience with congregations or legislative assemblies. It is the implied collateral relationship with monkeys, and the tradition engendered by medieval art that the devil has a tail that offends their dignity. The statement that the human species is descended from monkeys is merely polemical obscurantism and the playing on prejudices that started with Bishop Wilberforce-soapy Sam as he was called by some of his contemporaries and is a sort of Bryanesque smoke screen. As to lineage, man is not at all closely related to the existing monkeys or apes. They are the culmination of different lines of evolution, and this statement is especially true of the monkeys. That their ancestry in the far distant past approximated the human line or indeed may have merged with it millions of years ago in early Tertiary times is quite another matter. I find nothing in Genesis either for or against evolution. The language, to be sure, is not explicit (dust of the earth), but the special creation of man as opposed to the evolutionary creation is entirely an egoistical interpretation that is supposed, quite wrongly it seems to me, to add dignity to ourselves, and is of a cloth with the idea that the earth is the center of the universe-all the earth (homocentric) centering in man, and all the universe revolving around the earth-man's temporary abode. It is a most curious revelation in the workings of the human mind that so many good people grow indignant over the idea that man was made from a long line of animal ancestry as degrading; and yet who do not quarrel with the facts that each human starts his or her individual life as a single cell, and during the nine months preceding birth passes through a series of stages that roughly epitomize the main stages of evolution, even to possessing a rudimentary tail like an ape. Five hundred years ago we should have said that embryology was the invention of the devil to test the faith of the elect-exactly a reason that was once advanced to explain the fossils in the rocks. To-day most of us know better, and we find in the truth of creation far more to reverence than in the anthropomorphic deity of the childhood of the races. In approaching the geological record of evolution, I will state only facts and leave fundamental causes severely alone. The mechanism of evolution we leave to experimental biology, and I do not advocate any theories of explanation. Here is evolution. Here are the myriad of forms that moved across the stage of the past and were the actors in the drama of life. In geology, to borrow a simile from written history or philology, we are dealing with the original documents in so far as they were preserved as fossils, and in their actual order of succession. In approaching the geological record, the time conception is most important, and I can best illustrate this by a brief recital of the progress of knowledge concerning fossils. It is only in comparatively modern times that fossils have been recognized as the remains of animals and plants that had once been alive. The early Greeks were sane enough to recognize this apparently obvious relationship, and we find Xenophanes, 500 B. C., speculating on the fossils found in the quarries of Syracuse, Sicily. But during the middle ages there was no end to the discussion regarding the nature and origin of fossils. What seems strange in this year of grace may really not have been so strange in the days when the universally held belief was that of spontaneous generation, a flat earth created in six days, and the only past submergence of the land that of Noah's flood. Was it not the same "plastic force" in nature which traced the frost patterns and the moss agate that fashioned the fossils, and was there not every gradation from shells and bones that exactly resemble recent ones to mere stones of similar form and appearance? We now know that the mineral replaces the organic matter of a fossil. Was it strange to have believed three or four hundred years ago that the process was the reversefrom the mineral toward the organic? At any rate many strange theories were evolved to explain the fossils. One tells us that fossil shells were formed on the hills by the influence of the stars. Others called up a stone-making spirit. Others believed that fossils were the models made by the Creator in perfecting his handiwork before he essayed the task of making living organisms. I am quoting entirely the views of devout churchmen. Others believed that fossils were mere "figured stones," or were the abortive products of the germs of animals and plants that had lost their way in the earth, or that they were the invention of the devil to test the faith. Even after the belief that fossils were the remains of animals and plants had become well established, it was assumed that they had been killed by Noah's flood and stranded on the mountain tops-an interpretation suggested by Martin Luther in 1539 as secular proof of the correctness of the scriptural account. This flood theory found numerous advocates throughout the seventeenth and even far into the eighteenth century. It passed through various phases of opinion. At first, the fossils were regarded as similar to those still living in the vicinity-a natural enough belief when the universal acceptance of the Mosaic cosmology and a world but 6,000 years old is borne, in mind. Later, when the differences in the fossils became apparent, it was assumed that they had been swept to Europe and buried by the waters of the flood and represented forms still existing in the tropics. With the progress of knowledge of tropical organisms this last view became untenable, and it was thought that the fossils represented forms that had been exterminated by the flood, and from this it was but a slight step to the once popular belief that there had been no thistles or weeds or noxious insects in the Garden of Eden, that all creation had become base with the fall of man. Gradually it came to be recognized that fossils were not only frequently unlike recent organisms, but that they were very ancient, and not merely antediluvian, but preAdamitic-a view first advocated by Blumenbach in 1790. We are still far from a chronology. Granting that fossils were the traces of once living organisms and antedated Adam-what of it? When Guettard (Jean Etienne Guettard, 1715-1786) made one of the first geological maps, it wasn't really a geological map in the modern sense, but a map of what he called mineral bands (like a modern soil map). He had no idea of geological succession or of structure. The credit of recognizing fossils as the modals of creation we owe to the genius of William Smith (1769-1839) and to the orderly arrangement of the Mesozoic rocks of the English Midlands. Smith journeyed about for years in this region, where the succession of fossiliferous strata is an open book. In his work of building canals, roads and drains, he observed that each bed contained fossils, some of which were peculiar to it, and he found that he could recognize the same horizons and the same succession at many different localities. This important generalization has since been verified and end lessly extended. The contained fossils furnish the surest guides to the age of the sedimentary rocks that geology knows. To the biologist these facts have a deeper meaning, for they show that during the vast lapse of time, to be measured in tens or hundreds of millions of years, the living population of the globe has undergone almost continuous change, old simple forms becoming extinct, and newer, more specialized, forms taking their place, the change being, in general, from lower to higher, in other words-evolution. That God rested from his six days' task of creation just 4004 years B. C. is so absurd that I have yet to meet a person of normal mind who believes in Archbishop Usher's chronology. There have been many attempts to determine the age of the earth in yearscalculations of the rate of cooling of molten bodies, the rate of retardation by tidal friction, the thickness of the sedimentary rocks, the amount of dissolved salts added to the oceans by the rivers of the world, the condition of the radium minerals in igneous rocks. All methods contain unknown variables and are merely estimates. A favorite method has been to measure the thickness of a composite section of the sedimentary rocks, for the whole |