The Coming of Evolution Part 5

How well do I recollect my last visit to Lyell a day or two after this farewell interview with Huxley, the glow of grat.i.tude which lighted up the n.o.ble features as with trembling lips he told me how 'Huxley had repeated his whole Royal Inst.i.tution lecture at his bedside.'

Huxley was a most devoted student of Lyell. Speaking to his fellow geologists in 1869 he said, 'Which of us has not thumbed every page of the _Principles of Geology_[78]?' and writing in 1887 on the reception of the _Origin of Species_, he said:--

'I have recently read afresh the first edition of the _Principles of Geology_; and when I consider that this remarkable book had been nearly thirty years in everybody's hands, and that it brings home to any reader of ordinary intelligence a great principle and a great fact--the principle, that the past must be explained by the present, unless good cause be shown to the contrary; and the fact, that, so far as our knowledge of the past history of life on our globe goes, no such cause can be shown--I cannot but believe that Lyell, for others, as for myself, was the chief agent in smoothing the road for Darwin. For consistent uniformitarianism postulates evolution as much in the organic as in the inorganic world. The origin of a new species by other than ordinary agencies would be a vastly greater 'catastrophe' than any of those which Lyell successfully eliminated from sober geological speculation[79].'

How strongly Lyell had become convinced, as early as 1832, of the truth and importance of the doctrine of Evolution--in the _organic_ as well as in the inorganic world--in spite of his emphatic rejection of the theory of Lamarck, we shall show in the next chapter. It was this conviction, as we shall see, which led to his friendly encouragement of Darwin in his persevering investigations and to his constant solicitude that the results of his friend's labours should not be lost through delay in their publication.

CHAPTER VIII

EARLY ATTEMPTS TO ESTABLISH THE DOCTRINE OF EVOLUTION FOR THE ORGANIC WORLD

In studying the history of Evolutionary ideas, it is necessary to keep in mind that there are two perfectly distinct lines of thought, the origin and development of which have to be considered.

_First._ The conviction that species are not immutable, but that, by some means or other, new forms of life are derived from pre-existing ones.

_Secondly._ The conception of some process or processes, by which this change of old forms into new ones may be explained.

Buffon, Kant, Goethe, and many other philosophic thinkers, have been more or less firmly persuaded of the truth of the first of these propositions; and even Linnaeus himself was ready to make admissions in this direction. It was impossible for anyone who was convinced of the truth of the doctrine of continuity or evolution in the _inorganic_ world, to avoid the speculation that the same arguments by which the truth of that doctrine was maintained must apply also to the _organic_ world.

Hence we find that directly the _Principles of Geology_ was published, thinkers, like Sedgwick and Whewell, at once taxed Lyell with holding that 'the creation of new species is going on at the present day,' and Lyell replied to the latter:--

'It was impossible, I think, for anyone to read my work and not to perceive that my notion of uniformity in the existing causes of change always implied that they must for ever produce an endless variety of effects, _both in the animate and inanimate world_[80].'

And to Sedgwick, Lyell wrote:--

'Now touching my opinion,' concerning the creation of new species at the present day, 'I have no right to object, _as I really entertain it_, to your controverting it; at the same time you will see, on reading my chapter on the subject, that I have studiously avoided laying down the doctrine dogmatically as capable of proof. I have admitted that we have only data for _extinction_, and I have left it to be inferred, instead of enunciating it even as my opinion, that the place of lost species is filled up (as it was of old) from time to time by new species. I have only ventured to say that had new mammalia come in, we could hardly have hoped to verify the fact[81].'

That Lyell was convinced of the truth of the doctrine of the evolution of species is shown by his correspondence with friends and sympathisers like Scrope and John Herschel. But he wrote:

'If I had stated ... the possibility of the introduction or origination of fresh species being a natural, in contradistinction to a miraculous process, I should have raised a host of prejudices against me, which are unfortunately opposed at every step to any philosopher who attempts to address the public on these mysterious subjects[82].'

That Lyell was justified in not increasing the difficulties which would r.e.t.a.r.d the reception of his views, by introducing matter, which he still regarded as of a more or less speculative character, I think everyone will be prepared to admit. Darwin had to contend with the same difficulty in writing the _Origin of Species_. To have included the question of the origin of mankind _prominently_ in that work would have raised an almost insurmountable barrier to its reception. He says in his autobiography, 'I thought it best, in order that no honourable man should accuse me of concealing my views, to add that by the work "light would be thrown on the origin of man and his history." It would have been useless and injurious to the success of the book to have paraded, without giving evidence, my conviction with respect to his origin[83].'

Huxley and Haeckel have both borne testimony to the fact that Lyell, at the time he wrote the _Principles_, was firmly convinced that new species had originated by evolution from old ones. Indeed in a letter to John Herschel in 1836 he goes very far in the direction of antic.i.p.ating the lines in which enquiries on the _method_ of evolution must proceed, having even a prevision of the doctrine of _mimicry_, long afterwards established by Bates and others. Lyell wrote:--

'In regard to the origination of new species, I am very glad to find that you think it probable that it may be carried on through the intervention of intermediate causes. I left this rather to be inferred, not thinking it worth while to offend a certain cla.s.s of persons by embodying in words what would only be a speculation.... One can in imagination summon before us a small part at least of the circ.u.mstances that must be contemplated and foreknown, before it can be decided what powers and qualities a new species must have in order to enable it to endure for a given time, and to play its part in due relation to all other beings destined to coexist with it, before it dies out.... It may be seen that unless some slight additional precaution be taken, the species about to be born would at a certain era be reduced to too low a number. There may be a thousand modes of ensuring its duration beyond that time; one, for example, may be the rendering it more prolific, but this would perhaps make it press too hard upon other species at other times. Now if it be an insect it may be made in one of its transformations to resemble a dead stick, or a leaf, or a lichen, or a stone, so as to be somewhat less easily found by its enemies; or if this would make it too strong, an occasional variety of the species may have this advantage conferred on it; or if this would be still too much, one s.e.x of a certain variety. Probably there is scarcely a dash of colour on the wing or body of which the choice would be quite arbitrary, or which might not affect its duration for thousands of years. I have been told that the leaf-like expansions of the abdomen and thighs of a certain Brazilian Mantis turn from green to yellow as autumn advances, together with the leaves of plants among which it seeks its prey. Now if species come in succession, such contrivances must sometimes be made, and such relations predetermined between species, as the Mantis, for example, and plants not then existing, but which it was foreseen would exist together with some particular climate at a given time. But I cannot do justice to this train of speculation in a letter, and will only say that it seems to me to offer a more beautiful subject for reasoning and reflecting on, than the notion of great batches of new species all coming in and afterwards going out at once[84].'

We have cited this very remarkable pa.s.sage, as it affords striking evidence of how deeply Lyell had thought on this great question at a very early period. Nevertheless it is certain that when he wrote the second volume of the _Principles_, he had not been able to satisfy himself that any hypothesis of the _mode_ of evolution, that had up to that time been suggested, could be regarded as satisfactory.

The only serious attempt to _explain_ the derivation of new species from old ones that came before Lyell was that of the ill.u.s.trious Lamarck.

Very noteworthy was the work of that old wounded French soldier, afflicted in his later years as he was by blindness. By his early labours, Lamarck had attained a considerable reputation as a botanist, and later in life he turned his attention to zoology, and then to palaeontology and geology. In zoology, he did for the study of invertebrate animals what his great contemporary Cuvier was accomplishing for the vertebrates; but, with regard to the origin of species, he arrived at conclusions directly at variance with those of his distinguished rival.

We are indebted to Professor Osborn[85] for calling attention to that remarkable, but little known work of Lamarck's--_Hydrogeologie_--published in 1802, seven years before his _Philosophie Zoologique_ appeared. This work is especially interesting as showing to how great an extent--as in the case of Darwin, Wallace and others--it was geological phenomena which played an important part in leading Lamarck to evolutionary convictions.

"In Geology," Professor Osborn writes,

'Lamarck was an ardent advocate of uniformity, as against the Cataclysmal School. The main principles are laid down in his _Hydrogeologie_, that all the revolutions of the earth are extremely slow. "For Nature," he says, "time is nothing. It is never a difficulty, she always has it at her disposal; and it is for her the means by which she has accomplished the greatest as well as the least results[86]."'

On the subject of subaerial denudation (the action of rain and rivers in wearing down the earth's surface), Lamarck's views were as clear and definite as those of Hutton himself; though it is almost certain that he could never have seen, or even heard of, the writings of the great Scottish philosopher. On some other questions of geological dynamics, however, it must be confessed that Lamarck's views and speculations were rather crude and unsatisfactory.

In his _Philosophie Zoologique_, published in the same year that Charles Darwin was born (1809), Lamarck brought forward a great body of evidence in favour of evolution, derived from his extensive knowledge of botany, zoology and geology. He showed how complete was the gradation between many forms ranked as species, and how difficult it was to say what forms should be cla.s.sed as 'varieties' and what as 'species.'

But when he came to indicate a possible method by which one species might be derived from another, he was less happy in his suggestions. He recognised the value of the evidence derived from the study of the races which have arisen among domestic animals, and from the crossing of different forms. But his main argument was derived from the acknowledged fact that use or disuse may cause the development or the partial atrophy of organs--the case of the 'blacksmith's arm.' Unfortunately some of the suggestions made by Lamarck, in this connexion--like that of the elongation of the giraffe's neck to enable it to browse on high trees--were of a kind that made them very susceptible to ridicule. His theory was of course dependent on the admission that acquired characters were transmitted from parents to children, and in the absence of any suggestion of 'selection,' it did not appeal strongly to thinkers on this question.

Lyell first became acquainted with the writings of Lamarck in 1827. As he was returning from the Oxford circuit for the last time--having now resolved to give up law and devote himself to geological work exclusively--he wrote to his friend Mantell as follows:--

'I devoured Lamarck _en voyage_.... His theories delighted me more than any novel I ever read, and much in the same way, for they address themselves to the imagination, at least of geologists who know the mighty inferences which would be deducible were they established by observations. But though I admire even his flights, and feel none of the _odium theologic.u.m_ which some modern writers in this country have visited him with, I confess I read him rather as I hear an advocate on the wrong side, to know what can be made of the case in good hands. I am glad he has been courageous enough and logical enough to admit that his argument, if pushed as far as it must go, if worth anything, would prove that men may have come from the Ourang-Outang. But after all, what changes species may really undergo! How impossible will it be to distinguish and lay down a line, beyond which some of the so-called extinct species have never pa.s.sed into recent ones. That the earth is quite as old as he supposes, has long been my creed, and I will try before six months are over to convert the readers of the _Quarterly_ to that heterodox opinion[87].'

Lyell was at that time at work on his review for the _Quarterly_ of Scrope's _Central France_, and was also completing the 'first sketch'

of the _Principles_. But it is evident that as the result of continued study of Lamarck's book, Lyell found it, in spite of its fascination, to embody a theory which he could not but regard as unsound and not calculated to prove a solution of the great mystery of evolution.

Accordingly when the second volume of the _Principles_ was issued in 1832, it was found to contain in its opening chapters a very trenchant criticism of Lamarck's theory.

It is only fair to remember, however, that in 1863, after Lyell had accepted the theory of Natural Selection he wrote to Darwin:

'When I came to the conclusion that after all Lamarck was going to be shown to be right, and that we must "go the whole orang" I re-read his book, and remembering when it was written, I felt I had done him injustice[88].'

It is interesting also to notice that Darwin, like Lyell, gradually came to entertain a higher opinion of the merit of Lamarck's works, than he did on his first perusal of them. In 1844, Darwin wrote to Hooker, 'Heaven forfend me from Lamarck nonsense!' and in the same year he speaks of Lamarck's book as 'veritable rubbish,' an 'absurd though clever work[89].' When, after the publication of the _Origin of Species_, Lyell referred to the _conclusions_ arrived at in that work as similar to those of Lamarck, Darwin expressed something like indignation, and he wrote to their 'mutual friend' Hooker, 'I have grumbled a bit in my answer to him' (Lyell) 'at his _always_ cla.s.sing my book as a modification of Lamarck's, which it is no more than any author who did not believe in the immutability of species[90].' In this case, as is so frequently seen in the writings of Darwin, it is evident that he attaches infinitely less importance to the establishment of the _fact_ of the evolution of species, than to the demonstration of a possible _mode of origin_ of that evolution. But that later in life Darwin came to take a more indulgent view of the result of Lamarck's labours is shown by a pa.s.sage in his 'Historical Sketch' prefixed to the _Origin_, in 1866. Lamarck, he says, 'first did the eminent service of arousing attention to the probability of all change in the organic world, as well as in the inorganic world, being the result of law and not of miraculous interposition[91].'

In the opinion of Dr Schwalbe and others there are indications in Darwin's later writings that he had come into much closer relation with the views of Lamarck, than was the case when he wrote the _Origin_[92].

It is interesting, however, to note that Erasmus Darwin, the grandfather of Charles, published independently and contemporaneously, views on the nature and causes of evolution in striking agreement with those of Lamarck; but perhaps the poetical form, in which he chose to embody his ideas, led to their receiving less attention than they deserved.

As is now well known a number of writers during the earlier years of the nineteenth century published statements in favour of evolutionary views, and in several cases the theory of natural selection was more or less distinctly outlined. In addition to Geoffroy and Isidore Saint Hilaire and d'Omalius d'Halloy on the continent, a number of writers in this country, such as Dr Wells, Mr Patrick Matthew, Dr Pritchard, Professor Grant, Dean Herbert, all expressed views in favour of evolution, even, in some cases, foreshadowing Natural Selection as the method. But these authors attached so little importance to their suggestions, that they did not even take the trouble to place them on permanent record, and it is certain that neither Lyell nor Darwin was acquainted with their writings at the time they were themselves working at the subject.

There was indeed one work which, during the time that the _Origin of Species_ was in preparation, attracted much popular attention. In 1844, Robert Chambers, who was favourably known as the author of some geological papers, wrote a book which excited a great amount of attention--the well-known _Vestiges of Creation_. This work was a very bold p.r.o.nouncement of evolutionary views. Beginning with a statement of the nebular hypothesis of Kant and Laplace, it discussed the question of the origin of life--when life became possible on a cooling globe--and, arguing strongly in favour of the view that all plants and animals, as the conditions under which they existed change, had given rise to new forms, better adapted to their environment, insisted that the whole living creation had been gradually developed from the simplest types.

Chambers published his book anonymously, being naturally afraid of the prejudices that would be excited against him--especially in his own country--by a work so outspoken, and it was not till after his death that its authorship was definitely known.

The _Vestiges of Creation_ met with very different receptions at the hands of the general public and from the scientific world, at the time it was published. The former were startled but captivated by its fearless statements and suggestive lines of thought; while the latter were repelled and incensed by the want of judgment, too frequently shown, in accepting as indisputable, facts and experiments which really rested on a very slender basis or none at all. So popular was the book, however, that it pa.s.sed through twelve editions, the last being published after the appearance of the _Origin of Species_.

It is interesting to read Darwin's judgment in later life on this once famous book; he says:--

'The work from its powerful and brilliant style, though displaying in the earlier editions little accurate knowledge and a great want of scientific caution, immediately had a very wide circulation. In my opinion it has done excellent service in this country in calling attention to the subject, in removing prejudice, and in thus preparing the ground for the reception of a.n.a.logous views[93].'

If we enquire what was the att.i.tude of scientific naturalists towards the doctrine of Evolution, immediately before the occurrence of the events to be recorded in the next chapter, we shall find some diversity of opinion to exist. The late Professor Newton, an eminent ornithologist, has a.s.serted that, at this period, many systematic zoologists and botanists had begun to feel great 'searchings of heart'

as to the possibility of maintaining what were the generally prevalent views concerning the reality and immutability of species. Huxley, however, declared that he and many contemporary biologists were ready to say 'to Mosaists and Evolutionists a plague to both your houses!' and were disposed to turn aside from an interminable and fruitless discussion, to labour in the fields of ascertainable fact[94].

CHAPTER IX

DARWIN AND WALLACE: THE THEORY OF NATURAL SELECTION