The Coming of Evolution Part 6

Charles Darwin was the grandson of Erasmus Darwin, who, as we have seen, arrived independently at conclusions concerning the origin of species very similar to those of Lamarck, and embodied his views in poems, which, at the time of their publication, achieved a considerable popularity. In the younger philosopher, however, imagination was always kept in subjection by a determination to '_prove_ all things' and 'to hold fast that which is good'; though, in other respects, there were not wanting indications of the existence of hereditary characteristics in the grandson.

Born at Shrewsbury and educated in the public school of that town, Charles Darwin from the first exhibited signs of individuality in his ideas and his tastes. The rigid cla.s.sical teaching of his school did not touch him, but, with the aid of his elder brother, he surrept.i.tiously started a chemical laboratory in a garden tool-house. From his earliest infancy he was a collector, first of trifles, like seals and franks, but later of stones, minerals and beetles.

At the outset, only the desire to possess new things animated him, then a wish to put names to them, but, at a very early period, a pa.s.sion arose for learning all he could about them. Thus when only 9 or 10 years of age, he had 'a desire of being able to know something about every pebble in front of the hall-door,' and at 13 or 14, when he heard the remark of a local naturalist, 'that the world would come to an end before anyone would be able to explain how' a boulder (the 'bell-stone'

of local-fame) came to be brought from distant hills--the lad had such a deep impression made on his mind, that he says in after life, 'I _meditated_ over this wonderful stone[95].'

At the age of 16, he was sent to Edinburgh University to prepare himself for the work of a doctor--the profession of his father and grandfather.

But here his independence of character again a.s.serted itself. He found most of the lectures 'intolerably dull,' so he occupied himself with other pursuits, making many friendships among the younger naturalists and doing a little in the way of biological research himself.

That he was not altogether dest.i.tute of ambition in the eyes of his companions, however, is, I think, indicated by an amusing circ.u.mstance.

In the library of Charles Darwin, which is carefully preserved at Cambridge, there is a copy of Jameson's _Manual of Mineralogy_, published in 1821, which was evidently used by the young student in his cla.s.swork at Edinburgh. In this a quizzical fellow-student has written 'Charles Darwin Esq., M.D., F.R.S.'--mischievously adding 'A.S.S.'! Even for geology, the science to which in all his after life he became so deeply devoted, young Darwin conceived the most violent aversion; and as he listened to Jameson's Wernerian outpourings at Salisbury Crags, he 'determined never to attend to geology,' registering the terrible vow 'never as long as I lived to read a book on Geology, or in any way to study the science[96].'

As it became evident that Charles Darwin would never make a doctor, his father, after two years' trial, sent him to Cambridge with the object of his qualifying for a clergyman. But at Christ's College, in that University, he again took his own line--which was not that of divinity--riding, shooting and beetle-hunting being his chief delights.

Nevertheless, at Cambridge as at Edinburgh, he seems to have shown an appreciation for good and instructive society, and in Henslow, the judicious and amiable Professor of Botany, the young fellow found such sympathy and kindly help that he came to be distinguished as 'the man who walks with Henslow[97].'

After achieving a 'pa.s.s degree,' Darwin went back to the University for an extra term, and by the advice of Henslow began to 'think about' the despised Science of Geology. He was introduced to that inspiring teacher, Sedgwick, with whom he made a geological excursion into Wales; but though he said he 'worked like a tiger' at geology, yet he, when he got the chance of shooting on his uncle's estate, had to make the confession, 'I should have thought myself mad to give up the first days of partridge-shooting for geology or any other science[98].'

There is a sentence in one of the letters written at this time which suggests that, even at this early period in his geological career, Darwin had begun to experience some misgivings concerning the catastrophic doctrines of his teachers and contemporaries. He says:--

'As yet I have only indulged in hypotheses, but they are such powerful ones that I suppose, if they were put into action but for one day, the world would come to an end[99].'

Was he not poking fun at other hypotheses besides his own?

Darwin's real scientific education began when, after some hesitation on his father's part, he was allowed to accept the invitation, made to him through his friend Henslow, to accompany, at his own expense, the surveying ship _Beagle_ in a cruise to South America and afterwards round the world. In the narrow quarters of the little 'ten-gun brig,'

he learned methodical habits and how best to economise s.p.a.ce and time; during his long expeditions on sh.o.r.e, rendered possible by the work of a surveying vessel, he had ample opportunities for observing and collecting; and, above all, the absence of the distractions from quiet meditation, afforded by a long sea-voyage, proved in his case invaluable. Very diligently did he work, acc.u.mulating a vast ma.s.s of notes, with catalogues of the specimens he sent home from time to time to Henslow. He had received no careful biological training, and Huxley considered that the voluminous notes he made on zoological subjects were almost useless[100]. Very different was the case, however, with his geological notes. He had learned to use the blowpipe, and simple microscope, as well as his hammer and clinometer; and the notes which he made concerning his specimens, before packing them up for Cambridge, were at the same time full, accurate and suggestive.

Darwin has recorded in his autobiography the wonderful effect produced on his mind by the reading of the first volume of Lyell's _Principles_--an effect very different from that antic.i.p.ated by Henslow[101]. From that moment he became the most enthusiastic of geologists, and never fails in his letters to insist on his preference for geology over all other branches of science. Again and again we find him recording observations that he thinks will 'interest Mr Lyell' and he says in another letter:--

'I am become a zealous disciple of Mr Lyell's views, as known in his admirable book. Geologising in South America, I am tempted to carry parts to a greater extent even than he does[102].'

Before reaching home after his voyage, the duration of which was fortunately extended from two to five years, he had sent home letters asking to be elected a fellow of the Geological Society; and, immediately on his arrival, he gave up his zoological specimens to others and devoted his main energies for ten years to the working up of his geological notes and specimens.

It may seem strange that the grandson of Erasmus Darwin should in early life have felt little or no interest in the question of the 'Origin of Species,' but such was certainly the case. He tells us in his autobiography that he had read his grandfather's _Zoonomia_ in his youth, without its producing any effect on him, and when at Edinburgh he says he heard his friend Robert Grant (afterwards Professor of Zoology in University College, London) as they were walking together 'burst forth in high admiration of Lamarck and his views on Evolution'--yet Darwin adds 'I listened in silent astonishment, and as far as I can judge without any effect on my mind[103].'

The reason of this indifference towards his grandfather's works is obvious. All through his life, Darwin, like Lyell, showed a positive distaste for all speculation or theorising that was not based on a good foundation of facts or observations. In this respect, the att.i.tude of Darwin's mind was the very opposite of that of Herbert Spencer--who, Huxley jokingly said, would regard as a 'tragedy'--'the killing of a beautiful theory by an ugly fact.' Darwin tells us himself that, while on his first reading of _Zoonomia_ he 'greatly admired' it--evidently on literary grounds--yet 'on reading it a second time after an interval of ten or fifteen years, I was much disappointed; _the proportion of speculation being so large to the facts given_.' Huxley who knew Charles Darwin so well in later years said of him that:--

'He abhors mere speculation as nature abhors a vacuum. He is as greedy of cases and precedents as any const.i.tutional lawyer, and all the principles he lays down are capable of being brought to the test of observation and experiment[104].'

What then, we may ask, were the facts and observations which turned Darwin's mind towards the great problem that came to be the work of his after life? I think it is possible from the study of his letters and other published writings to give an answer to this very interesting question.

In November 1832, Darwin returned to Monte Video, from a long journey in the interior of the South American Continent, bringing with him many zoological specimens and a great quant.i.ty of fossil bones, teeth and scales, dug out by him with infinite toil from the red mud of the Pampas--these fossils evidently belonging to the geological period that immediately preceded that of the existing creation. The living animals represented in his collection were all obviously very distinct from those of Europe--consisting of curious sloths, anteaters, and armadilloes--the so-called 'Edentata' of naturalists. And when young Darwin came to examine and compare his _fossil_ bones, teeth and scales he found that they too must have belonged to animals (megatherium, mylodon, glyptodon, etc.) quite distinct from but of strikingly similar structure to those now living in South America. What could be the meaning of this wonderful a.n.a.logy? If Cuvier and his fellow Catastrophists were correct in their view that, at each 'revolution'

taking place on the earth's surface, the whole batch of plants and animals was swept out of existence, and the world was restocked with a 'new creation,' why should the brand-new forms, at any particular locality, have such a 'ghost-like' resemblance to those that had gone before? It is interesting to note that, just at the same time, a similar discovery was made with respect to Australia. In caves in that country, a number of bones were found which, though evidently belonging to 'extinct' animals, yet must have belonged to forms resembling the kangaroos and other 'pouched animals' (marsupials) now so distinctive of that continent. But of this fact Darwin was not aware until after his return to England in 1836.

Among the objects sent from home, which awaited Darwin on his return to Monte Video, was the second volume of Lyell's _Principles_, then newly published; this book, while rejecting Lamarckism, was crowded with facts and observations concerning variation, hybridism, the struggle for existence, and many other questions bearing on the great problem of the origin of species. I think there can be no doubt that from this time Darwin came to regard the question of species with an interest he had never felt before.

It is of course not suggested that, at this early date, Darwin had formed any definite ideas as to the _mode_ in which new species might possibly arise from pre-existing ones or even that he had been converted to a belief in evolution. Indeed in 1877 he wrote 'When I was on board the _Beagle_ I believed in the permanence of species' yet he adds 'but as far as I can remember _vague doubts_ occasionally flitted across my mind.' Such 'vague doubts' could scarcely have failed to have arisen when, as happened during all his journeys from north to south of the South American Continent, he found the same curious correspondence between existing and late fossil forms of life again and again ill.u.s.trated.

But towards the end of the voyage, an even stronger element of doubt as to the immutability of species was awakened in his mind. When he came to study the forms of life existing in the Galapagos Islands, off the west coast of South America, he was startled by the discovery of the following facts. Each small island had its own 'fauna' or a.s.semblage of animals--this being very strikingly shown in the case of the reptiles and birds. And yet, though the _species_ were different, there was obviously a very wonderful 'family likeness' to one another between the forms in the several islands and between them all and the animals living in the adjoining portion of the continent. Surely this could not be accidental, but must indicate relationships due to descent from common ancestors!

Charles Darwin returned to England in 1836, and at once made the acquaintance of Lyell. He says in one place, 'I saw a great deal of Lyell' and in another that 'I saw more of Lyell than of any other man, both before and after my marriage.' In one of his letters he writes, 'You cannot conceive anything more thoroughly good natured than the heart-and-soul manner in which he put himself in my place and thought what would be best to do[105].' For two years Darwin was comparatively free from the distressing malady which clouded so much of his after life. And, during that time, he engaged very heartily with Lyell in those combats at the Geological Society (of which he had become one of the Secretaries) in which their joint views concerning the truth of continuity or evolution in the inorganic world were defended against the attacks of the militant catastrophists. Darwin, however, did not act on the defensive alone, but brought forward a number of papers strongly supporting his new friend's views.

There can be little doubt that, while thus engaged, and in constant friendly intercourse with Lyell, Darwin must have felt--like other earnest thinkers on geology at that day--that the principles they were advocating of 'continuity' in the inorganic world must be equally applicable to the organic world--and thus that the question of evolution would acquire a new interest for him.

But it was undoubtedly the revision of the notes made on board the _Beagle_, and the study of the specimens which had been sent home by him from time to time, that produced the great determining influence on Darwin's career. All through the voyage he had endeavoured, with as much literary skill as he could command, to record with accuracy the observations he made, and the conclusions to which, on careful reflection, they seemed to point. And on his return to England, these patiently written journals were revised and prepared for publication forming that charming work _A Naturalist's Voyage. Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. 'Beagle' round the world._

As Darwin, with the specimens before him, revised his notes, and reconsidered the impressions made on his mind, the 'vague doubts' he had entertained, from time to time, concerning the immutability of species, would come back to him with new force and c.u.mulative effect. 'I then saw,' he says, 'how many facts indicated the common descent of species,'

and further, 'It occurred to me in 1837, that something might perhaps be made out on this question by patiently acc.u.mulating and reflecting on all sorts of facts which could possibly have any bearing on it.' In July of that year, he opened his first note-book on the subject[106]--the note-books being soon replaced by a series of portfolios, in which extracts from the various works he read, facts obtained by correspondence, the records of experiments and observation, and ideas suggested by constant meditation were slowly acc.u.mulated for twenty years. Mr Francis Darwin has published a series of extracts from the note-book of 1837, which amply prove that by this time Charles Darwin had become 'a convinced evolutionist[107].'

Fifteen months after this 'systematic enquiry' began, Darwin happened to read the celebrated work of Malthus _On Population_, for amus.e.m.e.nt, and this served as a spark falling on a long prepared train of thought. The idea that as animals and plants multiply in geometrical progression, while the supplies of food and s.p.a.ce to be occupied remain nearly constant, and that this must lead to a 'struggle for existence' of the most desperate kind, was by no means new to Darwin, for the elder De Candolle, Lyell and others had enlarged upon it; yet the facts with regard to the human race, so strikingly presented by Malthus, brought the whole question with such vividness before him that the idea of 'Natural Selection' flashed upon Darwin's mind. This hypothesis cannot be better or more succinctly stated than in Huxley's words.

'All _species_ have been produced by the development of _varieties_ from common stocks: by the conversion of these, first into _permanent races_ and then into _new species_, by the process of _natural selection_, which process is essentially identical with that artificial selection by which man has originated the races of domestic animals--the _struggle for existence_ taking the place of man, and exerting, in the case of natural selection, that selective action which he performs in artificial selection[108].'

With characteristic caution, Darwin determined not to write down 'even the briefest sketch' of this hypothesis, that had so suddenly presented itself to his mind. His habit of thought was always to give the fullest consideration and weight to any possible objection that presented itself to his own mind or could be suggested to him by others. Though he was satisfied as to the truth and importance of the principle of natural selection, there is evidence that for some years he was oppressed by difficulties, which I think would have seemed greater to him than to anyone else. In my conversations with Darwin, in after years, it always struck me that he attached an exaggerated importance to the merest suggestion of a view opposed to that he was himself inclined to adopt; indeed I sometimes almost feared to indicate a _possible_ different point of view to his own, for fear of receiving such an answer as 'What a very striking objection, how stupid of me not to see it before, I must really reconsider the whole subject.'

While a divinity student at Cambridge, Darwin had been much struck with the logical form of the works both of Euclid and of Paley. The rooms of the latter he seems to have actually occupied at Christ's College and the works of the great divine were so diligently studied that their deep influence remained with him in after life[109].

I think it must have been the remembrance of the arguments of Paley on the 'proofs of design' in Nature, that seem in after life to have haunted Darwin so that for long he failed to recognise fully that the principle of natural selection accounted not only for the _adaptation_ of an organism to its environment, but at the same time explains that _divergence_, which must have taken place in species in order to give rise to their wonderfully varied characters.

It was not till long after he came to Down in 1842, he tells us in his autobiography, that his mind freed itself from this objection. He says:--

'I can remember the very spot in the road, whilst in my carriage, when to my joy the solution occurred to me,'

and he compares the relief to his mind as resembling the effect produced by 'Columbus and his egg[110].' Some may think the 'solution' of Columbus was itself not a very satisfactory one; and I am inclined to regard the difficulties of which Darwin records so sudden and dramatic a removal as more imaginary than real!

There can be no doubt that, as pointed out by the late Professor Alfred Newton[111], there was among naturalists during the second quarter of the nineteenth century a feeling of dissatisfaction with respect to current ideas concerning the origin of species, accompanied in many cases with one of expectation that a solution might soon be found.

Others, however, despairingly regarded it as 'the mystery of mysteries'

for which it was hopeless to attempt to find a key. There was, however, one man, who simultaneously with Darwin was meditating earnestly on the problem and who eventually reached the same goal.

Alfred Russel Wallace was born thirteen years after Darwin, and a quarter of a century after Lyell. He did not possess the moderate income that permits of entire devotion to scientific research--an advantage, the importance of which in their own cases, both Lyell and Darwin were always so ready to acknowledge. Wallace, after working for a time as a land-surveyor and then as a teacher, at the age of 26 set off with another naturalist, H. W. Bates, on a collecting tour in South America--hoping by the sale of specimens to cover the expenses of travel. Like Lyell and Darwin, he was an enthusiastic entomologist, and had conceived the same pa.s.sion for travel. He had, as we have already seen, been deeply impressed by reading the _Principles of Geology_, and after spending four years in South America undertook a second collecting tour, which lasted twice that time, in the Malay Archipelago.

[Ill.u.s.tration: Alfred R. Wallace]

Before leaving England in 1848, Wallace had read and been impressed by reading the _Vestiges of Creation_, and there can be no doubt that from that period the question of evolution was always more or less distinctly present in his mind. While in Sarawak in the wet season, he tells us, 'I was quite alone with one Malay boy as cook, and during the evenings and wet days I had nothing to do but to look over my books and ponder over the problem which was rarely absent from my thoughts.' He goes on to say that by 'combining the ideas he had derived from his books that treated of the distribution of plants and animals with those he obtained from the great work of Lyell' he thought 'some valuable conclusions might be reached[112].' Thus originated the very remarkable paper, _On the Law which has regulated the Introduction of New Species_, the main conclusion of which was as follows: 'Every species has come into existence coincident both in s.p.a.ce and time with a pre-existing closely allied species.' As Wallace has himself said, 'This clearly pointed to some kind of evolution ... but the _how_ was still a secret.'

This essay was published in the _Annals and Magazine of Natural History_ in September 1855. It attracted much attention from Lyell and Darwin and later from Huxley. One important result of it was that Darwin and Wallace entered into friendly correspondence. But although Darwin in his letters to Wallace informed him that he had been engaged for a long time in collecting facts which bore on the question of the origin of species, he gave no hint of the theory of natural selection he had conceived seventeen years before--indeed his friends Lyell and Hooker appear at that time to have been the only persons, outside his family circle, whom he had taken into his confidence.

In the spring of 1858, Wallace was at Ternate in the island of Celebes, where he lay sick with fever, and as his thoughts wandered to the ever-present problem of species, there suddenly recurred to his memory the writings of Malthus, which he had read twelve years before. Then and there, 'in a sudden flash of insight' the idea of natural selection presented itself to his mind, and after a few hours' thought the chief points were written down, and within a week the matter was 'copied on thin letter-paper' and sent to Darwin by the next post, with a letter to the following effect[113]. Wallace stated that the idea seemed new to himself and he asked Darwin, if he also thought it new, to show it to Lyell, who had taken so much interest in his former paper. Little did Wallace think, in the absence of all knowledge on his part of Darwin's own conclusions, what stir would be made by his paper when it arrived in England!

Wallace's essay was ent.i.tled _On the Tendency of Varieties to depart indefinitely from the Original Type_, and it is a singularly lucid and striking presentment, in small compa.s.s, of the theory of Natural Selection.

Had these two men been of less n.o.ble and generous nature, the history of science might have been dishonoured by a painful discussion on a question of priority. Fortunately we are not called upon for anything like a judicial investigation of rival claims; for Darwin as soon as he read the essay saw that--as Lyell had often warned him might be the case--he was completely forestalled in the publication of his theory.

The letter and paper arrived at a sad time for Darwin--he was at the moment very ill, there was 'scarlet fever raging in his family, to which an infant son had succ.u.mbed on the previous day, and a daughter was ill with diphtheria[114].' Darwin at once wrote hurriedly to Lyell enclosing the essay and saying:

'I never saw a more striking coincidence; if Wallace had my MS.

sketch written out in 1842, he could not have made a better short abstract! Even his terms now stand as heads of my chapters. Please return me the MS., which he does not say he wishes me to publish, but I shall, of course, at once write and offer to send to any journal. So all my originality, whatever it may amount to, will be smashed, though my book, if it ever have any value, will not be deteriorated, as all the labour consists in the application of the theory. I hope you will approve of Wallace's sketch, that I may tell him what to say[115].'

And Wallace--what was the line taken by him in the unfortunate complication that had thus arisen? From the very first his action was all that is generous and n.o.ble. Not only did he, from the first, entirely acquiesce in the course taken by Lyell and Hooker, but, writing in 1870, when the fame of Darwin's work had reached its full height, he said:--