The History of Biological Theories

Empedocles is cited as a forerunner of Darwin. He taught that present-day organisms had arisen by the union of parts (heads, hands, feet, and so on), which united quite by chance and in all sorts of combinations. Only after the destruction of various irregular forms did they come together in their present shapes. It is forgotten that Empedocles a Pythagorean believed in the eternal changelessness of all creation; it is overlooked that his theory is as little Darwinian as is modern chemical theory, according to which the manifold forms of matter arise by different combinations of the same eternal, indestructible atom. If Empedocles be a Darwinist, so also was the first

unknown Roman who named the leopard leo-pardus, the giraffe camel-leo-pardus, names which suggest that these animals arose from a cross between lion and panther and between camel and the lion-panther cross. In the Middle Ages there was a persistent belief that a man and an animal could conceive a being half-animal, half-man. This, too, was just as much and just as little a Darwinian conception ! In the early nineteenth century geological thought was dominated by Cuvier's assumption that the face of the earth had undergone many changes. He believed that these had been caused by sudden catastrophes or cata- clysms. Cuvier sought to harmonize this view with the known facts concerning extinct animals. He suggested that the whole organic world was almost completely destroyed at each upheaval, and that later, new forms appeared in the devastated regions. He made no attempt to explain whence these new forms came. Very different opinions were held about the cause and number of these catastrophes.

In Germany there were two schools of geological thought. The 'Neptunists' asserted that all mountains originated in water ; the 'Vulcanists 3 that they were due to heat and volcanic action. Just as great diversity character- ized the theories as to the number of these upheavals. The French geologist Elie de Beaumont (1798-1879) at first thought that there had been seven, then he suggested twelve, fifteen, sixty, even a hundred as the probable number.

Morphologists, at this period, were comparing the living body to a crystal, and seeking for its symmetry. This way of thinking influenced geological speculation. Elie de Beaumont suggested, in his theory of the genesis of mountain chains formed by the cooling and shrinking of the earth's crust, that they lie on the sides of a regular rhombic dodecahedron circumscribed about the earth! its problems were attacked more practically. Charles Lyell, a lawyer and journalist, published his great Principles of Geology in 1830-2. He rejected the catastrophic theory, and explained most geological phenomena as the result of slight and slow changes similar to those still taking place. The forces at work are such as the attrition by rain, or the action of subterranean streams and lakes which undermine the solid crust, or volcanic action, which causes a rising or sinking of the surface of the earth.

The influence of Lyell' s theories was immense, and even to-day their essentials are accepted by geologists. It is true that in practice we distinguish between epochs we speak of primitive rocks, of palaeozoic, mesozoic, tertiary, quaternary epochs, and the like, and that we further subdivide each of these. We know in practice that the different formations of different periods have definite dis- tinguishing characters. We speak of causes, of which, it is true, we know little, bringing about the transition from one period to another, nor do we reject the possibility of non-terrestrial forces having contributed to these changes. In our theoretical considerations, however, both the earth and the human race are always thought of as possessing a continuous and unbroken history, and this attitude we owe largely to Lyell.

Lyell's work had a lasting effect upon Darwin. Through- out his voyage round the world Darwin had Lyell's geo- logical views in mind, and after his return to England he published a series of observations which seemed to him to support them. Later, when inquiring into the origin of species, it was therefore natural for him to attach great importance to the slight changes continually in progress around us. He kept in mind Lyell's view of the great antiquity of our earth, and the possibility of great altera- tions being the result of the summation of gradual action over a vast period of time.

The views of Lyell on the origin of life resembled those of Cuvier. He thought that climatic changes had forced animals and plants to migrate, and that the presence of varying forms of life in successive layers of the earth's crust was explicable on the basis of these migrations. In the very first of the numerous editions of his Geology ', how- ever, Lyell had drawn his readers' attention to Lamarck's theory, and his letters show us that, from the year 1827 onwards, he was fully alive to this idea of change in living forms, and was inclined to accept the new hypothesis*

3. Vestiges of the Natural History of Creation. In 1844 the attention of literary England was directed to the anonymously published Festiges of the Natural History of Creation. The book was generally attributed to Robert Chambers (1802-71), a journalist, traveller, and historical writer with some knowledge of geology. It was widely read both in English and in translations. In 1884 the twelfth edition appeared under Chambers' own name. It dealt with the origin of the world and of its animal inhabitants. It assumed that the living world was started on its path by Divine Providence and that life owed its origin to a chemico-electric process. By this process germ cells were created, and from these new and ever- changing forms were produced by discontinuous grada- tions, which gradually advanced towards ever greater perfection. These progressive grades were held to be analogous to the changes seen in the metamorphosis of jelly-fish, tape-worms, or insects. That species can undergo modification was illustrated by appeal to the supposed change of fungi into algae, and of wheat and oats into rye. A raven had once been seen with a beak like that of the sheldrake ; and the domestic pig can revert to its wild form. Living and extinct transitional forms were cited, as, for example, certain reptiles, which were thought to link fishes and snakes with crocodiles. The river lamprey (Petromyzon fluviatilis) was thought to be transitional between the worm, echinoderm or cephalopod,on the one hand, and the fish on the other. So too the frog, dolphin, sloth, bat, point the way towards man, who probably arose from a large frog which ultimately became extinct. The author drew a

parallel between the animal series and embryonic and palaeontological development, and pointed to the signifi- cance of vestigal organs, and of the anatomical similarity between different animals. The naivete of the outlook of the Vestiges roused the antagonism of men of science, who nevertheless read it eagerly. Wallace and Bates were stimulated by it to con- sider the origin of species (1848). It even influenced Darwin, who committed his views to paper for the first time and communicated them to his friends in the year of publication of the Vestiges*.

in 1809. As a boy he was a great collector of natural history specimens. The ordinary school work, however, did not attract him, neither, as he grew older, did medicine nor the suggestion that he should train for the Church. Following his natural bent he early devoted himself to biological studies. (He came of a well-to-do family in which an interest in natural science can be traced back throughout the eighteenth century. His grandfather, Erasmus Darwin (1731-1802), excelled not only as a physician, but as a poet, man of science, and philosopher. Erasmus was much in- fluenced by Rousseau, whom he knew personally. He adopted methods of 'natural healing' and endeavoured to hasten the patient's recovery by influencing his mind. He also turned his attention to the cure of inebriety, with, it is said, great practical results. As a poet he sought to discuss botanical problems in verse, and founded in England a peculiar school of descriptive scientific poetry. As a man of science he made many new observations on subjective vision and on vertigo. In this original work he was a forerunner of Purkinje. He published two ex- tensive scientific works, Zoonomia or the Laws of Organic Life (1794-6) and Phytologia or the Philosophy of .Agri- culture and Gardening (1799). These are based on the real- istic philosophy of Locke and Hume in an original, and sometimes in a laughable manner. The main object of these works is to explain the nature and origin of life. \

It was the view of Erasmus Darwin that Goer had originally created one living substance from which some very simple form of organic life developed. Gradually, from this, all animals and plants arose. He suggested the ideas of mimicry, and of sexual selection, and sought to explain conditions prevailing in the world by an appeal to our every-day experience. Charles Darwin made very little effort to relate his theory to that of his grandfather. His great dislike of abstract philosophy made him undervalue his grand- father's work, as he undervalued that of Lamarck. He failed to realize that scientific thought and scientific theories are of slow development that these, too, have a history. He looked upon the theories of both men as very fantastic.

CThe work of Erasmus Darwin was quite overshadowed by the great success of that of his grandson, and he was regarded as little more than an unimportant forerunner of the great Charles. Nevertheless, Erasmus was richer in original ideas and had a much greater literary insight than his grandson. The grandson was the superior in thorough- ness and perseverance. $ Charles Darwin, after his return from his voyage round the world, mingled in London with the most cultured Englishmen of his day. ' Among his friends were JLyell the geologist, Wheweu the philosopher and author of the History of the Inductive Sciences, Robert Brown the botanist, Buckle, author of the History ~oj Civilization in England, Macaulay and Carlyle. (He constantly dis- cussed their views with them. In his Autobiography he criticizes them in a manner that reveals him as the typical cultured Englishman of his day; while able to say something polite about each of them, he exhibits little real insight into their characters and less understanding of their fundamental ideas.)

Darwin was greatly impressed by Buckle's work by the tremendous knowledge it displayed, and the methodical way in which facts were gathered from the most diverse sources for use in support of his theories. For Carlyle, on the other hand, not only had he no sympathy but he regarded him with ill-concealed derision. If it be true that a man's estimate of another be the best clue to his own character, we may look on these facts as significant. The remark of Darwin concerning Carlyle, who was dowered with a rich fancy, is eloquent enough. 'As far as I could judge/ says Darwin, 'I never met a man with a mind so ill adapted for scientific research. 5 )

Darwin has told us that the two men whose work greatly influenced him during his student days were Herschel and Humboldt. He made a collection of abstracts from Hum- boldt's writings, and was glad that he was about to travel 'as Humboldt had done'. He began this journey in 1831 in the Beagle, a ship fitted out by the English Government to explore the coast of South America. During the voyage he was chiefly interested in geology. Lyell's book had recently appeared, and in South America Darwin sought evidence in support of Lyell's theory of gradual changes in the earth's crust. He also followed on Humboldt's line of work, being much interested in the geographical dis- tribution of plants and animals. After his return from the voyage in the Beagle he took no post, but gave his whole time to his scientific work. Much of his life was passed in the seclusion of a country residence. He died in

Members of the Paris Academy accused Darwin of dilettantism. He belonged to no school, was neither botanist nor zoologist, geologist nor physiologist; he followed none of the prevailing lines of thought ; he was neither morphologist nor embryologist. He gave his attention to one question after another, passing from an explanation of the origin of coral reefs to the question of the origin of species, from the study of the movements of plants to that of mimicry and to the development of the human face. The theories which he originated are ex- tremely English in form. They are founded on experience rather than on reason, and are original but not profound. The arguments are monotonous and embody little search- ing of the mind, j The greatness of the work lies rather in its system and in the multiplicity of the phenomena cited in support of its theories.

At the end of the eighteenth and beginning of the nineteenth centuries the teaching of the utilitarian philo- sopher jj^ngLjLBentl^am was spreading in England./ Ben- tham taught that morality is based on man's likes and dislikes, that the moral is merely the useful, that man only avoids sin because he fears discovery and its consequences. The individual, it is true, cannot give free rein to all his desires, but he need only control them when they conflict with the interests of society. \

('The greatest happiness of the greatest number* is the keynote to this egoistic morality. It sought the origin of the moral sense in man's social life, with its inevitable conflicts between individual interests, rather than in some inborn quality of the human soul. Bentham's work, in which these ideas were developed, appeared in 1789. In 1778 Adam Smith had published his Wealth of Nations, a treatise dealing with the laws of political economy. According to Smith, man is an egoist relentlessly pursuing his individual aims. That society will become the most wealthy which does least to restrain the individual in the economic struggle, which leaves him free to buy in the cheapest and sell in the dearest market. }

These moral and political ideas for the analogy between the two is obvious fell in England upon fertile ground, and became the foundation of the so-called laissez-faire school of political economy. The country was in process of transformation from an agricultural to an industrial state, andrthe big industrialists found in Adam Smith's teaching good arguments against various protective laws, privileges and taxes which they disliked. More and more the ideal state was assumed to be one that merely protected the freedom and property of the citizen, without hamper- ing his individual liberty, and laws and regulations wr did not fit this view were gradually repealed.

The work of the philosophers of the period was a strange medley of logic and psychology. Wri their observations with some psychological analysis. They would take one phenomenon, selling, for example. They would examine the psychological processes connected with it and deduce one or two fundamental catch-phrases, as for example, 'supply and demand'. They then discussed these as the driving principles in the 'selling process'. They would endeavour to deduce the result if a com- munity should obey the one law 'buy cheap and sell dear'. Thus they reached conclusions which they believed to be as important as facts elicited by observation and dependent upon natural laws.)

Thomas Robert Malthus (1766-1834) in his Essay on Population, first published in 1798 and often reprinted, followed the same type of reasoning. His axioms are well known. ( That mankind is always striving for happiness served as his starting-point. Then followed the question Why has man's longing for progress so little result ? If we look at the life of the community more closely, said Malthus, we see that man has an inborn desire to reproduce his kind. Food too is needed that he may live. These, the desire for food and the desire to multiply, are the driving forces behind all human progress J,

/ How, by considering the antagonism between these two factors, Malthus continued, can we arrive at present condi- tions f Man increases rapidly, in geometric progression, but his available food only in arithmetic progression. Hence must arise shortage of food, hence hunger, disease, over- work, under-feeding of children, overcrowding, war, and all manner of disaster. From this he inferred that man, to be happy, must restrict his desire to reproduce. The happiness of mankind becomes the controller of each individual's tendency to over-multiply.

These views of Malthus aroused considerable discussion, and in 1834 we trace their influence in the changes in the English poor law. The liberal movement reached its height in the thirties, after the July revolution in France. The same line of thought was followed still further. It was continued and further worked out in Buckle's History of Civilization in England, (1857-61). Buckle strove to convince his readers that history should become a science. The subject-matter of this science was to be the laws of the human spirit and the influence of such factors as climate, soil, food, &c., upon mankind,.

Such were the thoughts which dominated England when Darwin appeared. He was, it is true, neither a professional politician nor a political economist. It is possible that he had never read Bentham or Smith; he says nothing of the influence of Mill on his views. But he had read Malthus, he tells us, in 1838, when he had been con- sidering the origin of species for over a year. (The influence that the ideas of Malthus exerted on him is seen in the second edition of his Journal^ It is well known that he accepted the Malthusian view 01 over-population and deduced from it the struggle for existence. (^What is not so fully recognized is that the influence on him of these theorists in political economy was very great that his whole conception of nature, his whole scientific out- look, was dominated by them. 1 ^)

All pre-Darwinian writers, not excepting Lamarck, saw in Nature individual animals and individual plants, whose bodies and bodily functions were similar and subject to similar laws, thus testifying to an underlying unity. They often spoke of 'Nature', but for them this word meant a spiritual or even a mechanical principle which, working according to definite law, gave rise to the phenomena of the physical world. The individual, whether plant, animal,

1 The Origin of Species was a very large book, and its subject-matter was very new. These two characteristics probably account for the fact that the close resemblance between Darwin's reasoning and the logic of the laissez-faire economists passed unnoticed. The reader should examine Darwin's paper, 'Extracts from an as yet unpub- lished work on the idea of Species' (which was read before the Linnean Society in 1858, simultaneously with Wallace's paper), if he wishes to see how similar the two really were.

Darwin's paper is quite unmistakably written on the pattern of the laissez- faire economists. It is hardly more than an application of their reasoning to the facts of nature, and in this paper he refers to Malthus' theory more than he does in his later work. or man, was but the expression of an eternal law. The destruction of the one, of the many, of the whole world, meant nothing more than the disappearance of the visible manifestations of eternal laws laws quite independent of life and death. )

(^ For Darwin, however, true son of practical England, Nature consisted of separate parts. The death of an individual meant for him a change in Nature, the death of a hundred such, a hundredfold greater change. He looked at the whole living world from the point of view of the political economists. It consisted of a society, a state, of separate plants and animals, each following its own individual impulse. The economists pictured the state as a unit consisting of individuals whose egotism was only held in check by the egotism of others. So Darwin thought of Nature as made up of individuals, each follow- ing his own interests and living his own life.* Thus he arrived at a new and wonderful conception, the view of plants and animals as members of a community the community of Nature. The Liberalism of the day denied to the state the right to limit individual freedom ; Darwin combated the belief in any higher law which con- trols Nature and regulates the relations of animals to each other. Laws only arise from the combined individualistic tendencies of the plants and animals themselves.

It is impossible to understand why Darwin influenced the sociological theorists so profoundly, unless we realize that his whole teaching really constitutes a sociology of Nature, and that Darwin merely transferred the prevailing English political ideas and applied them to Nature.) He took his logical method from Malthus. He began from a single definite fact, based on observation, namely, that the number of individuals increases at a rapid rate. He considered what would be the result of this tendency should it act unchecked ; he concluded that it would lead to a struggle for existence, and he called the deduction thus arrived at a 'natural law'. Laissez faire, laissez passer; la nature va d?elle meme was the famous watchword

of those times. vThe politicians emphasized this doctrine on the practical side to prevent the state from any active interference in the rights of its citizens.) Laissez faire, laissez passer was the negation of the old law of the divine right of kings. Darwin, in his theory, accepted the second half of this sentence and wrote his book on the theme La nature va d'elle meme. There is no God-given law in Nature. Darwin began with two assumptions ; firstly, that the species is an artificially determined group of existents, and, secondly, that present-day forms are the results of selection.

I. When Darwin commenced to study the question of species many views on the subject were in existence those, for example, of Buffon and Linnaeus, the definitions of Cuvier, the ideas of Lamarck and of such morphologists as the De Candolles. But Darwin ignored such 'philo- sophic' discussions. His method was to collect, from works on floriculture, entomology, gardening, and animal-breed- ing, cases in which the author could not say whether a certain plant or animal constituted a variety or a species. He showed that there was no general agreement on the subject, and drew attention to the way in which new species are created by the specialists. ^