Evolution
Modern evolution, or the theory of life continuously descending from life with change, may be said to have had its first marked development in Comte de Buffon (1707–1788), a man of wealth and station, yet an industrious compiler, a brilliant writer, and a popularizer of science. He was not, however, a true scientific investigator, and his monument to fame is his Histoire Naturelle, in forty-four volumes, 1749–1804. A. S. Packard in his book on Lamarck, his Life and Work, 1901, concludes in regard to Buffon as follows:
“The impression left on the mind, after reading Buffon, is that even if he threw out these suggestions and then retracted them, from fear of annoyance or even persecution from the bigots of his time, he did not himself always take them seriously, but rather jotted them down as passing thoughts.... They appeared thirty-four years before Lamarck’s theory, and though not epoch-making, they are such as will render the name of Buffon memorable for all time.”
Chevalier de Lamarck (1744–1829) may justly be regarded as the founder of the doctrine of modern evolution. Previous to 1794 he was a believer in the fixity of species, but by 1800 he stood definitely in favor of evolution. Locy in his Biology and its Makers, 1908, states his theories in the following simplified form:
“Variations of organs, according to Lamarck, arise in animals mainly through use and disuse, and new organs have their origin in a physiological need. A new need felt by the animal [due to new conditions in its life, or the environment] expresses itself on the organism, stimulating growth and adaptations in a particular direction.”
To Lamarck, “inheritance was a simple, direct transmission of those superficial changes that arise in organs within the lifetime of an individual owing to use and disuse.” This part of his theory has come to be known as “the inheritance of acquired characters.”
Georges Cuvier (1769–1832), a peer of France, was a decided believer in the fixity of species and in their creation through divine acts. In 1796 he began to see that among the fossils so plentiful about Paris many were of extinct forms, and later on that there was a succession of wholly extinct faunas. This at first puzzling phenomenon he finally came to explain by assuming that the earth had gone through a series of catastrophes, of which the Deluge was the most recent but possibly not the last. With each catastrophe all life was blotted out, and a new though improved set of organisms was created by divine acts. The Cuvierian theory of catastrophism was widely accepted during the first half of the nineteenth century, and in America Louis Agassiz was long its greatest exponent. It was this theory and the dominance of the brilliant Cuvier, not only in science but socially as well, that blotted out the far more correct views of the more philosophical Lamarck, who held that life throughout the ages had been continuous and that through individual effort and the inheritance of acquired characters had evolved the wonderful diversity of the present living world.
In 1830 there was a public debate at Paris between Cuvier and Geoffroy Saint-Hilaire, the one holding to the views of the fixity of species and creation, the other that life is continuous and evolves into better adapted forms. Cuvier, a gifted speaker and the greatest debater zoology ever had, with an extraordinary memory that never failed him, defeated Saint-Hilaire in each day’s debate, although the latter was in the right.
A book that did a great deal to prepare the English-speaking people for the coming of evolution was “Vestiges of Creation,” published in 1844 by an unknown author. In Darwin’s opinion, “the work, from its powerful and brilliant style... has done excellent service... in thus preparing the ground for the reception of analogous views.” This book was recommended to the readers of the Journal (48, 395, 1845) with the editorial remark that “we cannot subscribe to all of the author’s views.”
We can probably best illustrate the opinions of Americans on the question of evolution just before the appearance of Darwin’s great work by directing attention to James D. Dana’s Thoughts on Species (24, 305, 1857). After reading this article and others of a similar nature by Agassiz, one comes to the opinion that unconsciously both men are proving evolution, but consciously they are firm creationists. It is astonishing that with their extended and minute knowledge of living organisms and their philosophic type of mind neither could see the true significance of the imperceptible transitions between some species, which if they do not actually pass into, at least shade towards, one another.
Dana speaks of “the endless diversities in individuals” that compose a species, and then states that a living species, like an inorganic one, “is based on a specific amount or condition of concentered force defined in the act or law of creation.” Species, he says, are permanent, and hybrids “cannot seriously trifle with the true units of nature, and at the best, can only make temporary variations.” “We have therefore reason to believe from man’s fertile intermixture, that he is one in species: and that all organic species are divine appointments which cannot be obliterated, unless by annihilating the individuals representing the species.”
Through the activities of the French the world was prepared for the reception of evolution, and now it was already in the minds of many advanced thinkers. In 1860 Asa Gray sent to the editor of the Journal (29, 1) an article by the English botanist, Joseph D. Hooker, entitled “On the Origination and Distribution of Species,” with these significant remarks:
“The essay cannot fail to attract the immediate and profound attention of scientific men.... It has for some time been manifest that a re-statement of the Lamarckian hypothesis is at hand. We have this, in an improved and truly scientific form, in the theories which, recently propounded by Mr. Darwin, followed by Mr. Wallace, are here so ably and altogether independently maintained. When these views are fully laid before them, the naturalists of this country will be able to take part in the interesting discussion which they will not fail to call forth.”
Hooker took up a study of the flora of Tasmania, of which the above cited article is but a chapter, with a view to trying out Darwin’s theory, and he now accepts it. He says, “Species are derivative and mutable.” “The limits of the majority of species are so undefinable that few naturalists are agreed upon them.”
Asa Gray had received from Darwin an advance copy of the book that was to revolutionize the thought of the world, and at once wrote for the Journal a Review of Darwin’s Theory on the Origin of Species by means of Natural Selection (29, 153, 1860). This is a splendid, critical but just, scientific review of Darwin’s epoch-making book. Evidently views similar to those, of the English scientist had long been in the mind of Gray, for he easily and quickly mastered the work. He is easy on Dana’s Thoughts on Species, which were idealistic and not in harmony with the naturalistic views of Darwin. On the other hand, he contrasts Darwin’s views at length with those of the creationists as exemplified by Louis Agassiz, and says “The widest divergence appears.”
Gray says in part:
“The gist of Mr. Darwin’s work is to show that such varieties are gradually diverged into species and genera through natural selection; that natural selection is the inevitable result of the struggle for existence which all living things are engaged in; and that this struggle is an unavoidable consequence of several natural causes, but mainly of the high rate at which all organic beings tend to increase.
Darwin is confident that intermediate forms must have existed; that in the olden times when the genera, the families and the orders diverged from their parent stocks, gradations existed as fine as those which now connect closely related species with varieties. But they have passed and left no sign. The geological record, even if all displayed to view, is a book from which not only many pages, but even whole alternate chapters have been lost out, or rather which were never printed from the autographs of nature. The record was actually made in fossil lithography only at certain times and under certain conditions (i.e., at periods of slow subsidence and places of abundant sediment); and of these records all but the last volume is out of print; and of its pages only local glimpses have been obtained. Geologists, except Lyell, will object to this,—some of them moderately, others with vehemence. Mr. Darwin himself admits, with a candor rarely displayed on such occasions, that he should have expected more geological evidence of transition than he finds, and that all the most eminent paleontologists maintain the immutability of species.
The general fact, however, that the fossil fauna of each period as a whole is nearly intermediate in character between the preceding and the succeeding faunas, is much relied on. We are brought one step nearer to the desired inference by the similar ‘fact,’ insisted on by all paleontologists, that fossils from two consecutive formations are far more closely related to each other, than are the fossils of two remote formations.
It is well said that all organic beings have been formed on two great laws; Unity of type, and Adaptation to the conditions of existence.... Mr. Darwin harmonizes and explains them naturally. Adaptation to the conditions of existence is the result of Natural Selection; Unity of type, of unity of descent.”
Gray’s article was soon followed by another one from Agassiz on Individuality and Specific Differences among Acalephs, but the running title is “Prof. Agassiz on the Origin of Species” (30, 142, 1860). Agassiz stoutly maintains his well known views, and concludes as follows:
“Were the transmutation theory true, the geological record should exhibit an uninterrupted succession of types blending gradually into one another. The fact is that throughout all geological times each period is characterized by definite specific types, belonging to definite genera, and these to definite families, referable to definite orders, constituting definite classes and definite branches, built upon definite plans. Until the facts of Nature are shown to have been mistaken by those who have collected them, and that they have a different meaning from that now generally assigned to them, I shall therefore consider the transmutation theory as a scientific mistake, untrue in its facts, unscientific in its method, and mischievous in its tendency.”
Dana, in reviewing Huxley’s well known book, Man’s Place in Nature (35, 451, 1863), holds that man is apart from brute nature because man exhibits “extreme cephalization” in that he has arms that no longer are used in locomotion but go rather with the head, and because he has a far higher mentality and speech. As for the Darwinian theory, the evidence, he says, “comes from lower departments of life, and is acknowledged by its advocates to be exceedingly scanty and imperfect.”
The growth of evolution is set forth in the Journal in Asa Gray’s article on Charles Darwin (24, 453, 1882), which speaks of the latter as “the most celebrated man of science of the nineteenth century,” and, in addition, as “one of the most kindly and charming, unaffected, simple-hearted, and lovable of men.” In regard to the rise of evolution in America, more can be had from Dana’s paper on Asa Gray (35, 181, 1888). Here we read, as a sequel to his Thoughts on Species, that the “paper may be taken, perhaps, as a culmination of the past, just as the new future was to make its appearance.” Finally, in this connection there should be mentioned O. C. Marsh’s paper on Thomas Henry Huxley (50, 177, 1895), wherein is recorded the latter’s share in the upbuilding of the evolutionary theory.
We have seen that originally Dana was a creationist, but in the course of his long and fruitful life he gradually became an evolutionist, and rather a Neo-Lamarckian than a Darwinian. This change may be traced in the various editions of his Manual of Geology, and in the last edition of 1895 he says his “speculative conclusions” of 1852 in regard to the origin of species are not in “accord with the author’s present judgment.” “The evidence in favor of evolution by variation is now regarded as essentially complete.” On the other hand, while man is “unquestionably” closely related in structure to the man-apes, yet he is not linked to them but stands apart, through “the intervention of a Power above Nature.... Believing that Nature exists through the will and ever-acting power of the Divine Being, and... that the whole Universe is not merely dependent on, but actually is, the Will of one Supreme Intelligence, Nature, with Man as its culminant species, is no longer a mystery.”
In America most of the paleontologists are Neo-Lamarckian, a school that was developed independently by E. D. Cope (1840–1897) through the vertebrate evidence, and by Alpheus Hyatt (1838–1902) mainly on the evidence of the ammonites. They hold that variations and acquired characters arise through the effects of the environment, the mechanics of the organism resulting from the use and disuse of organs, etc. One of the leading exponents of this school is A. S. Packard, whose book on Lamarck, His Life and Work, 1901, fully explains the doctrines of the Neo-Lamarckians.