The History of Biological Theories

1 'Qui in locis authenticis Librorum sacrorum quidpiam falsi contineri posse existimant, ii profecto aut catholicam divinae inspirationis notionem pervertunt, aut Deum ipsum faciunt erroris auctorem.' 'Enzyklika Providentissimus Deus' of Pope Leo XIII, 1893. controversy between modern biological theorists and the Church. In De Maillet we find a carefully worded anti- clerical polemic, and a fuller one in Robinet. The latter devotes the whole of the second volume of his Natural Philosophy to an investigation of the cosmogonies of different nations, and to the proof that the story given by Moses cannot be accepted as literal truth. He concludes from the Greek text of the Bible (e ofy ovrw tnolrjCFev avTa 6 0eo's) that we need not assume that God created the world out of nothing. He prefers the hypothesis that there is a periodic growth and decay of the world, and he quotes sentences from St. Augustine and St. Origen which seem to him to support this view.

Cuvier showed that the extinct animals are distributed in periods of time, and on this he based his catastrophic theory. This theory cannot be reconciled with the first and second chapters of Genesis; these chapters tell us that the earth 'was without form and void', not that it became so. That was, however, the least of the difficulties. In the Biblical story only one Act of Creation is described. There is no reference to any water, to any rocks, continents, or plants which preceded the present ones. Neverthe- less, the Church did not oppose Cuvier, for he did not stress those conflicting points which were the logical deductions from his theory.

In matters of religion Darwin was a true son of his times a free-thinker. He did not deny the existence of a God, but for him it was an empty word, for it represents neither the Creator nor the lord of Creation, neither the inspirer of morality nor keeper of the soul. He plays no part in the world's story, neither in its past nor in its future. One thing only did He do for this world He created the first forms of life, and then, having created them, left them free to 'evolve' as they would.

in the Universe, nor did he believe the Universe to be controlled in any way by God. By mere suggestions at first, but later as a definite theory, he affirmed that Man is no more than a more highly developed monkey. He examined dogs in an endeavour to find the beginnings of religious sensibility; he thought that it was quite useless to begin a scientific inquiry into the nature of religion, for religion is unscientific. Although religious thought has played so great a part in human life, he did not think it necessary to study the facts of religion, nor to consider the views of the great religious teachers. He thought, as does the man in the street, that he was well qualified to discuss the nature of religious conviction after having read two or three books on the subject.

His ignorance angered the specialists. Max Miiller, for example, speaks of him with something like con- tempt. Rationalists of the old school, like von Baer and the Duke of Argyll, were offended by the general attitude of Darwin and even more of Haeckel, to feelings which they themselves, in spite of all their 'liberalism', held most sacred. In their struggle with the Church, the German materialists, on the other hand, gave a very hearty welcome to Darwinism. 'Science is the most effective weapon which we can use against either Jesuits (whether Catholic or Lutheran) or the Ultramontanes,' wrote G. Seidlitz (1875), and by 'science 5 in this connexion he really meant Darwinism.

Strauss was most enthusiastic about the new ideas, and in Der Alte und der neue Glaube, he gave a full explanation of Darwin's views, and added: 'The theory is still incomplete ; but there is something in these ideas which has an irresistible attraction for all those whose spirits thirst for truth and freedom. It was all very well for us philosophers and critically-minded theologians to banish the supernatural. Our decrees were uttered in vain; we did not know how to dispense with it ; we did not know any natural processes which would replace it in those realms which seemed peculiarly its own. Darwin re- vealed those natural forces, those natural processes. He opened a

door through which we might now thrust the supernatural into eternal banishment. All who know what belief in the supernatural has meant will acclaim him as among the great liberators of the human spirit.' These words show us what the materialists were promising themselves from the new faith. The anticlerical, almost antireligious, tendency of the whole theory was one of its chief recommendations, and the Darwinists were very sensitive about the 'Credo 5 of their co-workers. Those who were anti-Darwinian were decried as Papists and reactionaries.

Von Baer, Wigand, Owen, and Cuvier were dismissed as old fashioned; the Church took them all under her broad wing, never asking whether they really belonged there, and She defended them all, though unskilfully, against the intolerance of the Darwinists. The theologians were not united in their attitude to- wards Darwinism. The story of Galileo gave them caution, but it was impossible to accept the materialism of the new theory. Soon after the publication of the Origin of Species, Bishop Wilberforce wrote a criticism of the book (1860). Darwin was, according to him, a superficial thinker who had ' wandered from the broad highway . . . into a jungle of fanciful assumptions' and 'flimsy speculations' (Quarterly Review, 1860). He suggested that it is not very likely that Man has been evolved from a potato, and he allowed many similar foolish witticisms to appear under his name.

All theologians did not adopt this attitude, however. Darwin, in the Origin of Species, refers to 'a celebrated author and divine' who wrote to him that 'he has gradually learnt to see that it is just as noble a conception of the Deity to believe that He created a few original forms capable of self-development into other and needful forms, as to believe that He required a fresh act of creation to supply the voids caused by the action of His laws'. In later times, theologians wavered between these two views.

Huxley met with great opposition from orthodox ecclesiastical circles when he publicly proclaimed his belief that Man is descended from an ape-like ancestor. At the meeting of the British Association held in Oxford in 1860 there was a pitched battle between Bishop Wilberforce and Huxley. In 1864 a definite opposition to the new ideas was organized. Two hundred and ten scientists, among whom were Day, Brewster, and Balfour, declared that 'there cannot be any contradiction between the divine revelation given to us in the book of Nature and that revelation which is contained in the Bible. It is much to be regretted that certain scientists have attempted to use their science to question the accuracy of God's Holy Book.' Many scientists, however, whose religious views were quite orthodox, refused to sign this declaration.

Among German protestants the new theory soon gained many adherents, who accepted it either in part or as a whole. Zockler has given an account of this movement, and he himself criticized the theory very freely. More recently, the idea of evolution has not been absolutely rejected even by Roman Catholic theologians. 1 The theologians found themselves in a difficult position. They knew something about modern science, and did not want to appear quite unscientific. In all haste they adopted a few scientific ideas, and are full of wise saws and modern scientific instances. They cited Cuvier to refute Darwin, Darwin to contradict Huxley, Huxley to silence Haeckel. Listening attentively to their discussions, we are sometimes tempted to believe that they had a higher regard for these scientists than have the biologists them- selves. 2

There were a few scientists who attempted to reconcile the theory of evolution and the belief in the literal ac- curacy of the Bible. Soon after its publication, St. George 1 The names of some of these are given by Duilhe St. Projet in Apologie de la foi cbretiennC) 1885. Wasmann also gives the names of certain of them. 2 In the Kircberlexikon (1886) an account of Darwinism is given, culled from scientific sources only; the criticism is also a scientific one, taken from Wigand's works.

Mivart criticized the Origin of Species from this point of view. He discovered gaps in the theory of natural selection, and brought these to the notice of Darwin. He himself did not wholly reject the idea of evolution; he did not even object to the view which derived Man from an ape-like progenitor; but he felt convinced that God must have directly intervened when Man was first created. Lyell and Wallace both favoured this idea, and Mivart gained a considerable reputation.

Somewhat later (1904) Erich Wasmann, a Jesuit, created a certain sensation by his discussion of these problems. 1 He attempted to effect a reconciliation be- tween the Church and Darwin and between Darwin and the Church. He is really attacking both points of view. He not only accepts and defends the general doctrine of evolution, but he even admits that it is probably applica- ble to Man. We must, however, believe, according to him, that God actively intervened twice in the whole story; once when life began, and once again when the human soul was created. Apart from these two interventions, the whole process goes forward without any direct control by the Deity. God was, however, essential for these two events, for living material is absolutely different from life- less matter. God added something to lifeless matter before life could arise. The human soul is a further addition, which could only have been breathed into the animal body by God Himself.

Wasmann's criticism of Darwinism is not very enlighten- ing. He calls it, for example, 'mere tomfoolery done in the name of science', 'philosophical ineptitude', 'theologi- cally nonsense', 'social nonsense'. 'Haeckelism,' he says, 'aided by Darwinism, has become a pillar of Anarchism and of Social Democracy, as Bebel recently pointed out in the Reichstag.' He showed that the general belief in Church circles had been that there exist just as many species as were

1 E. Wasmann, Die moderns Biologie und die Entwicklungstbeorie, Freiburg im Br., 1904. originally created. (Linnaeus held this view.) To recon- cile this view with the ideas of Darwin, Wasmann postulated a difference between 'natural' and 'systematic' species. The species, for the purposes of the systematist, is just what we usually understand by a species Equus caballus, a horse. A 'natural' species, however, includes all forms which are related by descent. Thus the horse, the donkey, the zebra, and the hipparion all really descended from the one ancestral 'horse', form a 'natural' species.

Wasmann also accepted the idea of natural selection, and suggested that it might be made more comprehensive by being combined with an idea of friendly selection ('Amikal Selektion'). He quotes the ants and other insects as examples of this. The ants, as is well known, bring up the young of another species in their nests. They prefer insects which give off large amounts of fat, and they nurse the larvae of these 'ant friends' as they would nurse their own brood.

Wasmann's personality is so stimulating that his books are still read. Thus an 'open debate' between him and Plate aroused a great deal of interest. Plate is a typical Darwinist of the old school and judges religion purely from the scientific point of view. Apart from these occasional outbursts, the controversy between the Church and exact science seems to be ended. We all realize now that the Bible does not give us any accurate scientific details, and so, to defend it, we have merely to admit this fact. The attitude of the modern churchman, as of the evolutionist, to this strife is perhaps best expressed in the words of Vogelsang, a witty geologist, who remarked:

'If Moses had only kept his geological theories to himself, Christendom would have lost nothing, but science would have gained immeasurably, for its development would have been more rapid.' 1 But times have altered. We have abandoned all belief in the literal interpretation of the Bible, and no longer ask whether it was possible to crowd so many animals into Noah's Ark. Modern scientific criticism of the Bible is no longer based on physical science, but has taken an historical and philosophical turn.

Even this type of criticism is now giving place to a renewed interest in religion. If we regard the theology of Karl Earth as symptomatic of the new attitude to Darwinism and to Biblical criticism, what a change is here epitomized ! WE all realize that plants and animals are beautiful. Butterflies, humming-birds, orchids, roses, seem like beauty personified. This may reveal itself as beauty of form as we see in the markings of a butterfly's wing or in the human body, or in colour and texture, as in the rose, or in the velvety blackness of the mole; in scent; in motion, as we see it in the galloping horse, the bounding stag, or the wonderful curves described by the water- wagtail. There are beautiful sounds too, from the chirping of the grasshopper to the song of the nightingale. There are still other forms of beauty which we may specify the beauty, for example, revealed by animals at play and in the forms of animals, and, finally, there is spiritual beauty.

The evolutionary philosophers believed that beauty, like everything in the universe, is merely the result of other qualities. They did not seek out or describe natural beauty, but assumed that it was generally recognized. They considered that it was their task to see how it might be accounted for historically i. e. from the past history of the organism.- Herbert Spencer, for example, was looking at a table laden with good food, the dishes all elaborately garnished with green-stuff; in the middle were bowls full of fruit, and a vase of flowers. What thoughts did this sight arouse in his mind ? We might suppose that his first idea would be a realization of the. beauty of the objects spread out before him! But no he thought of something very different ; of primitive man still a tree dweller, living on the fruits of the untilled earth ; and to him the well-laid table was 'explained' merely as a relic, a legacy, of those far-off times! Grant Allen, an evolutionary philosopher, not only found nothing bizarre in this idea, but he elabo- rated it still further.

Darwin himself attributed almost all beauty to utili- tarian motives: 'With respect to the belief that organic beings have been created beautiful for the delight of Man, I may first remark that the sense of beauty obviously depends on the nature of the mind, irrespective of any real quality in the admired object ; and that the idea of what is beautiful is not innate or unalterable Flowers rank among the most beautiful productions of nature ; but they have been rendered conspicuous in contrast with the green leaves, and in consequence at the same time beautiful, so that they may be easily observed by insects. I have come to this conclusion from finding it an invariable rule that, when a flower is fertilized by the wind, it never has a gaily-coloured corolla* (Origin of Species).

Nature does not create beauty directly according to Darwin. What we call beauty is the result of the action of the environment, or of 'spontaneous variations and the complex laws of growth' ; and we may conclude that other- wise 'the structure of every living creature either now is, or was formerly, of some direct or indirect use to its possessor'. Darwin admits that the secondary sexual characters form an exception to this rule. He believes, too, that animals possess a sense of beauty, but he cannot explain how they have acquired it. 'Habit in all these cases appears to have come to a certain extent into play; but there must be some fundamental cause in the constitution of the nervous system in each species' (Origin of Species).

It follows from this theory that we cannot hope that a study of Nature will reveal to us any fundamental aestheti- cal laws. We must abandon the idea that by studying the structure, markings, colour, movements, or any other features of plant or animal organization, we can ever learn anything about the ultimate value of beauty. We know all there is to know about beauty in Nature and all that we can do is to ask how that beauty was acquired. True to his usual method, Darwin looked to many quarters for the 'cause' of beauty. The celestial blue, the colours of the rainbow, the glories of autumn colouring in trees, the colour and brilliance of precious stones, the

colours of the lowest animals all these are the results of natural laws. The Infusorian Opalina shimmers with all the colours of the rainbow, because light is refracted by its vibrating cilia. Many and various are the causes of the wealth of colour exhibited by so many of the simpler forms of life by corals, medusae, starfish, echino- derms, and the like; here the colours are useful to the organism in some way, there they are the direct effect of its physical and chemical structure, and hence neither useful nor the reverse. The blood is not red because the red colour is useful ; nor is it red in order that it may beautify the maiden's blushing cheek. The colour is simply the result of its chemical composition.

The beauty of flowers arose in yet another way. Many of these use insects for pollination. Since brightly coloured flowers are more easily noticed by insects, they are more often visited by them and are more likely to be pollinated. We owe most types of beauty, however, to the action of sexual selection. Even in quite lowly forms of life it is assumed that the female chooses for her mate the male who is most to her taste. The offspring of this union will inherit the advantages of their father and thus, step by step, beauty increases. So have arisen the bright colours of the butterflies, the glories of the peacock, the song of the nightingale, the beauty of mankind ! For this reason males tend to be more attractive than females ; they pass on all their characteristics, more particularly to their own sex. In his Descent of Man Darwin gives many facts in support of this theory. He cites many cases where the male differs from the female in form, colour, or marking; and he explains all these cases in the usual way. The peacock's feathers, the horny covering of the beetle, the colour of skin, of hair and of beard in Man for all these, as for all animal beauty whatsoever, Darwin gave what is really a psychological explanation. The taste of the female is the exciting cause of masculine beauty the cause of it, not the reason for its existence. If this were not so, we could deduce the taste of the female from a study of the

beauty of her male partner. Any such experiment, any attempt to formulate general laws of beauty, would be quite un-Darwinian. Darwin firmly upheld the maxim de gustibus non est disputandum. Grant Allen's theory of sexual selection was rather different. In his Colour Sense, a book on comparative aesthetics, he drew attention to the fact that the animals which haunt beautiful flowers and fruits are always them- selves beautifully coloured, while those which live on a diet of flesh, like all those which live in the soil, are dingy in colour. The American humming-birds and the South African Nectariniidae are among the loveliest of birds, and both these groups live on flowers. This is true, too, of the flower-haunting beetles and butterflies. Birds of prey, dung beetles, and nocturnal animals are, on the other hand, usually inconspicuous. Allen felt that these facts proved that the taste of the animal is moulded by its surroundings, and that the male (or female) chooses its mate according to the taste thus formed. Many molluscs and snails have shells beautifully formed, marked, and coloured. Grant Allen could only suggest that all such features must be the result of 'mere chance'.

Darwin found in Hermann Miiller (a secondary school teacher working in Lippstadt) a most industrious disciple, who whole-heartedly adopted his theory of floral structure. By this theory he sought to explain the harmony that so often exists between the shape of the flower and the size and mode of life of the pollinating insect (Darwin, Charles, On the Various Contrivances by which Orchids are fertilized by Insects, 1862). Miiller collected many observations relating to this phenomenon. Many floral structures apparently exist for the sole purpose of attract- ing insects. The insects use their eyes and their organs of scent to find the blossoms, while the flowers, on their part, display various attractive mechanisms the bright colours so often exhibited by calyx, corolla, stamens, floral axis, and bracts; the massing of many inconspicuous flowers into an inflorescence which stands out well from its surround-

ings ; the enlargement of the marginal florets in the Com- positeae all these serve as attractive devices to catch the eye of the insect, as the sweet scent of the flower affects his sense of smell. This theory of mutual adaptation will explain many striking features of floral structure and especially those structures which force the visiting insect to enter the flower in some special way, and thus make the transmission of pollen more certain, as in the Salvias, the Orchids, in Aristolochia, &c., &c.

Miiller divided flowers, according to their adaptation to certain insects, into butterfly flowers, moth flowers, wasp flowers, bee flowers, fly flowers, &c. Dianthus, for example, is only visited by butterflies ; Epipactis latifolia only by wasps ; Silene nutans, which is only scented at night, by night-flying moths. Many scientists, like Darwin and Miiller, thought that floral beauty existed for such uses only. The theory had, however, its critics.