Darwin and the Theory of Evolution/Chapter 1

by Carroll Lane Fenton

DARWIN AND THE THEORY OF
EVOLUTION

CHAPTER I

THE ORIGIN OF SPECIES

Darwin owed more to the early workers in evolution than generally is admitted, or he himself supposed. To an even greater extent he paralleled the work of his predecessors, many of whose books he had not even read. Thus even the theory of natural selection was published while Darwin still believed in special creation, although the mention of it was buried in a huge volume of timber suitable for naval construction.

This does not, of course, show that Charles Darwin lacked originality, or that his work lacked merit. Man began to wonder about the origin of living things long before he had the slightest inkling of either science or philosophy, and it is only natural that the more he knew the more he would speculate about that which he did not know. The early speculations, which dealt with gods rather than with animals or plants, soon were subjected to scrutiny along with the facts that they attempted to explain. Twenty-four centuries before the birth of Darwin, the Greek philosopher Thales taught that all life originated in the sea, and developed in accordance with natural law rather than the wills of the gods. In the eighteenth century, Goethe, Erasmus Darwin, and Geoffroy St. Hilaire came quite independently to the conclusion that species were not permanent, and each offered some explanation of the process of change. Following them came Lamarck, a leader of the French anti-creationists, who published, between the years of 1800 and 1815, a series of books, whose great thesis was that every living thing, including man himself, was descended from some earlier, and in most cases simpler living thing. These books attracted much attention, especially because of the opposition which they aroused, and undoubtedly did much to prepare continental Europe for the coming of evolution.

Inasmuch as Lamarck was the foremost evolutionist to precede Darwin, it is worth while to know what influence he may have exerted, and what his ideas were. In the first place, he saw clearly that species were not distinct units, as the earlier naturalist has supposed. Instead, they were more or less artificial definitions, applied to animals and plants that constantly varied, and among which there often was almost perfect graduation from one group to another. In addition, Lamarck saw that the domesticated species were not constant, and could be changed at will, even though they maintained fairly uniform distinctions. In explaining changes in form, color, and so on, he supposed that there was a very close correlation between the characters of a plant or animal and the conditions of its life, the circumstances of crossing with other species, and by habits causing an increase or decrease of certain parts—all underlain by a universal tendency for perfection. According to Lamarck, the giraffe has a long neck because his ancestors used their necks to reach food, while the snake lacks legs because his ancestors crawled on their bellies until their legs disappeared. This was the theory of "inheritance of acquired characters"—a theory sponsored by Darwin's grandfather, and which even today is far from being settled either favorably or otherwise.

So far as we can tell, Lamarck did not go far to convince Charles Darwin that species were the product of natural forces, nor did he furnish much material for the young naturalist's study. Indeed, it seems probable that Darwin did not read Lamarck's books in the original French, for he had great difficulty with the language. This, perhaps, accounts for the slighting and even contemptuous references to the books which one may find in several of the letters. In the second edition of the Journal of Researches, he describes a South American animal, whose habits resemble those of the mole, and which frequently is blind, and comments, "Considering the strictly subterannean habits of the Tucutuco, the blindness, though so common, cannot be a very serious evil . . . . Lamarck would have been delighted with this fact had be known it when speculating (probably with more truth than usual with him) on the gradually acquired blindness of the Aspalax, a gnawer living underground, and of the Proteus, a reptile living in dark caverns filled with water, in both of which animals the eye is in an almost rudimentary state, and is covered with a tendinous membrane of skin. … no-doubt Lamarck would have said that the Tucutuco was passing into the state of Aspalax and Proteus." In another letter he describes his work on evolution to Hooker, and adds, "Heaven forefend me from Lamarck nonsense of a 'tendency to progression,' 'adaptations from the slow willing of animals,' etc!"

There is, of course, the possibility that by reading Lamarck, and noting his obvious errors, Darwin was stimulated to seek more facts, and better bases for interpreting them. When he first read the Zoonomia, the principal evolutionary work of his grandfather, he was not greatly impressed. Yet in his later judgment of this book, he says, "Nevertheless, it is probable that the hearing, rather early in life^[1], such views maintained and praised, may have favored my upholding them in a different form in my Origin of Species.” It would not be hard to include Lamarck with Erasmus Darwin in this acknowledgment.

It is plain, therefore, that Darwin was acquainted with the general conception of the evolution of life some years before he went upon the Beagle as naturalist. That he did not consider the idea as either probable or even suggestive of truth is shown by his own statement that, while on the voyage, he accepted the Bible literally, and along with it, the theory of special creation. But the reading of Lyell's Principles of Geology—in which Lamarck's—hypotheses are quite fully explained—and the study of similarities between living and fossil forms in South America combined to bring about uncertainty, and in the end, a complete change of opinion. Thus in 1834, though still a believer in special creation, he was able to explain various facts only by admitting that species gradually became modified and, in his own words, "the subject haunted" him. Yet he was so unwilling to accept the evidence of his own observation that, in 1839, he sent his Journal to the printer with numerous references to special creation, and no mention of another explanation that seemed to him far more satisfactory.

Darwin seems to have accepted the idea of evolution, some time in 1836 or early in 1837, for he opened his first notebook in July of the latter year. Concerning his method he says, "I worked on true Baconian principles, and without any theory collected facts on a wholesale scale, more especially with respect to domesticated productions, by printed inquiries, by conversation with skillful breeders and gardeners, and by extensive reading. When I see the list of books of all kinds which I read and abstracted, including whole series of Journals and Transactions, I am surprised at my industry. I soon perceived that selection was the keynote of man's success in making useful races of animals and plants. But how selection could be applied to organism living in a state of nature remained for some time a mystery to me."

The reading and abstracting continued for fifteen months before Darwin found an answer to his question as to how a method of selection akin to that practiced by the breeder might be carried out among creatures not tampered with by man. While reading Malthus' now famous essay on Population^[2] the idea that, inasmuch as the struggle for food and other necessities of life was just as pressing among all other organisms as among man, there was a ready explanation of the means by which a purely natural selection could be carried on age after age, without the slightest necessity for guidance by some superior intellect. Under such conditions it would be only natural that the favorable variations would tend to be preserved, while the unfavorable ones were destroyed. The result of this would be the formation of new species. "Here then," says Darwin, "I had at last got a theory by which to work; but I was so anxious to avoid prejudice, that I determined not for some time to write even the briefest sketch of it. In June, 1842, I first allowed myself the satisfaction of writing a very brief abstract of my theory in pencil in 35 pages; and this was enlarged during the summer of 1844 into one of 230 pages, which I had fairly copied out and still possess.

"But at this time I overlooked one problem of great importance; and it is astonishing to me, except on the principle of Columbus and his egg, how I could have overlooked it and its solution. This problem is the tendency in organic beings descended from the same stock to diverge in character as they become modified. That they have diverged greatly is obvious from the manner in which species of all kinds can be classed under genera, genera under families, families under sub-orders and so forth; and I can remember the very spot in the road, whilst in my carriage, when to my joy the solution occurred to me; and this was long after I had come to Down. The solution, as I believe, is that the modified offspring of all dominant and increasing forms tend to become adapted to many and highly diversified places in the economy of nature."

It was at about this time that Darwin began to feel real confidence in the results of his reading and experimentation. In January of 1844, before writing out the second statement of his ideas, he wrote to Hooker:

… I have now been, ever since my return, engaged in a very presumptuous work, and I know no one individual who will not say a foolish one. I was so struck with the distribution of the Galapagos organisms, etc., and with the character of the American fossil mammifers, etc., that I determined to collect, blindly, every sort of fact, which could bear in any way on what are species. I have read heaps of agricultural and horticultural book, and have never ceased collecting facts. At last gleams of light have come, and I am almost convinced. (quite contrary to the opinion I started with) that species are not (it is like confessing a murder) immutable… I think I have found out (here's presumption!) the simple way by which species become exquisitely adapted to various ends. You will now groan, and think to yourself, 'on what a man I have been wasting my time and writing to.' I should, five years ago, have thought so. …^[3]

This was the first time Darwin mentioned the subject to Hooker—or for that matter, to anyone outside of his own household. But the great botanist neither groaned nor regretted the time he had spent in writing; instead, he accepted the earliest possible invitation to meet Darwin at his brother's house in London. After that Hooker frequently came to Down, sometimes alone, and sometimes in the company of other naturalists. After the work of evolution became well established, visits became matters of scientific inquiry as well as friendship.

"It was an established rule," says Hooker, "that he every day pumped me, as he called it, for half an hour or so after breakfast in his study, when he first brought out a heap of slips with questions botanical, geographical, etc., for me to answer, and concluded by telling me of the progress he had made in his own work, asking my opinion on various points. I saw no more of him till noon, when I heard his mellow ringing voice calling my name under my window—this was to join him in his daily forenoon walk round the sand-walk.^[4] … Our conversation usually ran on foreign lands and seas, old friends, old books, and things far off to both mind and eye."

Even after writing out his conclusions on the development of life, and the conditions underlying evolution, Darwin was not ready to publish. There were more facts to collect, and minor theories to verify, and he was unwilling to have his work appear before it was so complete as to be quite convincing. At the same time he realized that there was chance of his death, in which case the results of those years of patient labor might be lost, or used imperfectly. The following letter, written on July 5, 1844, and addressed to Mrs. Darwin, tells how highly the manuscript was prized:

I have just finished my sketch of my species theory. If, as I believe, my theory in time be accepted even by one competent judge, it will be a considerable step in science.

I therefore write this in case of my sudden death, as my most solemn and last request, which I am sure you will consider the same as if legally entered in my will, that you will devote 400 pounds to its publication. … I wish that my sketch be given to some competent person, with this sum to induce him to take trouble in its improvement and enlargement. I give to him all my books on Natural History, which are either scored or have references at the end of the pages, begging him carefully to look over and consider such passages as actually bearing, or by possibly bearing, on this subject. I wish you to make a list of all such books as some temptation to an editor. I also request that you will hand over to him all those scraps, roughly divided in eight or ten brown paper portfolios. The scraps, with copied quotations from various works are those which may aid my editor… As the looking over the references an scraps will be a long labour, and as the correcting and enlarging and altering my sketch will also take considerable time, I leave this sum of 400 pounds as some remuneration, and any profits from the work. I consider that for this the editor is bound to get the sketch published either at a publisher's or his own risk. …

With respect to editors, Mr. Lyell would be the best if he would undertake it; I believe he would find the work pleasant, and he would learn some facts new to him. As the editor must be a geologist as well as a naturalist, the next best editor would be Professor Forbes of London. The next best (and quite best in many respects) would be Professor Henslow. Dr. Hooker would be very good. … Should one other hundred pounds make the difference of procuring a good editor, request earnestly that you will raise 500 pounds.

This letter gives us, aside from a glimpse of the value which Darwin gave his "sketch," an interesting estimation of his various scientific friends, so far as their connection with evolution was concerned. The estimate changed in time, for ten years later another notation was made on the letter, reading, "Hooker by far best man to edit my species volume. August, 1854."

Fortunately Darwin's ill health, though painful and hampering in the extreme, did not seriously threaten his life, and there was no need to follow out the directions of the letter. The work of reading, observing, and experimenting, went on year after year. The puzzling problem of variation among animals and plants yielded to a solution—not a complete one by any means, yet one that was sufficient for the time. The concept of selection grew in importance, until it became the principal feature of the work. Yet as the information accumulated the magnitude of the problem became more clear, and Darwin still hesitated to publish what he considered an incomplete statement of the question and its answer.

During these years of investigation, general interest in the beginning and development of life increased. The same year that Darwin wrote his much-prized sketch, there appeared an anonymous book called the Vestiges of Creation. which some people attributed to Darwin. The book was written in a brilliant style, but particularly in the earlier editions, contained a great number of inaccuracies. As Darwin wrote Hooker, "his geology strikes me as bad, and his zoology far worse," while the general tone of the book was far from philosophic. Yet it did expound an idea of evolution, even though a poor one, and had a very large sale. Even Darwin, devotee to accuracy and caution, admitted that the book did great service in calling attention to the subject, in removing a great deal of prejudice, and in preparing the popular mind for other and more accurate information in the same field.

Finally, in 1856, Lyell persuaded Darwin to prepare his work for publication, and he began work on a scale that would have resulted in three or four volumes the sizes of the Origin of Species. The project was brought to a sudden halt, however, when in 1858 Alfred Russell Wallace, then a young man living in the Malay Archipelago, sent Darwin a manuscript entitled On the Tendency of Varieties to Depart Indefinitely from the Original Type. The matter was placed before Lyell and Hooker, who advised that, inasmuch as Darwin had been at work on his theory of species long before Wallace, it was only fair that steps should be taken to give proper credit for his pioneer work. Darwin objected to this, and was willing to leave Wallace the entire field, but his friends would not hear to it.

As a result of their persuasion, Lyell and Hooker sponsored the publication, in the Journal of the Linnean Society for June 30, 1858 a group of papers, including two short ones by by Darwin^[5] and Wallace's essay. With these went a statement as to the work done by each author, establishing clearly the priority of Darwin. The papers, however, did not attract much attention, for Darwin says, "… the only published notice of them which I can remember was by Professor Haughton of Dublin, whose verdict was that all that was new in them false, and what was true was old."

In spite of the great similarity of ideas, as shown by their papers, Darwin and Wallace differed considerably in the attitude from which they approached and regarded the problem,_As Dr. Osborn points out, "Darwin dwells upon variations in single characters, as taken hold of by Selection; Wallace mentions variations, but dwells upon full-formed varieties, as favorably or unfavorably adapted. It is perfectly clear that with Darwin the struggle is so intense that the chance of survival of each individual turns upon a single and even slight variation. With Wallace, Varieties are already presupposed by causes which he does not discuss, a change in the environment occurs, and those varieties which happen to be adapted to it survive." Needless to say, of the two methods of approach, that of Darwin is by far the more thorough-going.

Wallace resigned the work in favor of Darwin, who in 1858 set to work upon a book on the development of species, but was so interrupted by illness that more than a year was necessary to complete it. In the main it was a condensation of the work begun in 1856 and interrupted by the arrival of Wallace's paper—a condensation which Darwin did not desire, but undertook in order to prevent further difficulty in matters of priority, and to gratify his friends. Throughout the period of the work there are references to it in his letters—here the refusal to read a "heavy" book until the work on the "Abstract" is done—there a wish that the work would be completed, so he could rest. On January 25th, 1859, Darwin wrote Wallace, "… thank God I am in my last chapter but one," while on March 2d he asked Hooker if he could look over the chapter on Geographical Distribution. There is an amusing note to a letter of March 28, where Darwin asks Lyell:

Would you advise me to tell Murray (his publisher) that my book is not more un-orthodox than the subject makes inevitable. That I do not discuss the origin of man. That I do not bring in any discussion about Genesis, etc., etc., and only give facts, and such conclusions from them as seem to me fair.

Or had I better say nothing to Murray, and assume that he cannot object to this much unorthodoxy, which in fact is not more than any Geological Treatise which runs slap counter to Genesis.

Evidently Mr. Murray did not have great doubts as to lack of orthodoxy—nor as to the probable sale of the book, for a few days later Darwin wrote, "… I wrote him and gave him the headings of the chapters, and told him he could not have the MS. for ten days or so; and this morning I receive a letter offering me handsome terms, and agreeing to publish without seeing the MS.! So he is eager enough. …" Later on, three sample chapters were sent to Murray, who confirmed his acceptance of the book. The work of writing and copying went on, and various chapters were sent to specialists for comment and, if necessary, correction. There was much difficulty with style, and even Mrs. Hooker assisted in making corrections. Even after the manuscript went into the hands of the printer corrections were necessary after the material was "set up" in type. Probably Darwin became more and more dissatisfied as the work went on and his health became worse, for on June 22d he wrote Hooker, "… how can a man have anything to say, who spends every day in correcting accursed proofs; and such proofs! I have fairly to blacken them, and fasten slips of paper on, so miserable have I found the style. You say you dreamt that my book was entertaining; that dream is pretty well over with me. . . ." But gradually the work lessened; on September 30th the last of the regular pages were finished, and only the index remained to be done. It appears that it was handled by someone else, for in the same letter Darwin mentions the practical completion of the book and the plan to go to a hydropathic hospital on "Tuesday or Wednesday." When the next letters were written the Origin of Species was finished, and its author had spent a couple of weeks in rest. To him it was neither a great book, nor even a well-done one; after thirteen months of exacting labor he could see little in it that another could not have done with more success. Yet, even with his knowledge of its incompleteness and imperfections, Darwin was glad it was written—and impatiently eager for it to appear and meet the judgment of those who had taken no part in its production.

1. Darwin was eighteen when he learned of Lamarck, and even younger when he read Zoonomia.
2. Thomas R. Malthus was an English clergyman who wrote on subjects of political economy. His most famous work, and the one which so aided Darwin is titled, Essay on the Principles of Population as it Affects the Future Improvement of Society, and was published in 1798. Malthus believed that "population unchecked goes on doubling itself every twenty-five years—or increases in geometrical ratio. The rate according to which the productions of the earth increase must be totally of a different nature from the ratio of the increase of population. … The power of propagation being in every period so much superior (to that of production), the increase of the human species can only be kept down to the level of the means of subsistence by the constant operation of the strong law of necessity, acting as a check on the greater power.”

   It is easy to see how this exposition applied to the problem on which Darwin was working, and the assistance it must have given him.

3. Here we have a conflict in dates. It is plain that Darwin did not trouble to decide definitely at what time he did begin to believe in evolution, or to admit its possibility, and the various dates depend upon the varying viewpoints from which he considered his attitude at the time he wrote.
4. See the account of the Home at Down, in "Darwin As a Naturalist," No. 567 in this Series.
5. One of these papers was a mere extract from Darwin's larger manuscript; the other was an abstract of a letter to Dr. Asa Gray, an American botanist. The whole took up a little more than six pages.