The Evolution of Man, vol 2, Ernst Haeckel [online e reader txt] 📗

to the embryo. A piece of the paternal soul goes with-the spermatozoon, and a piece of the mother’s soul remains in the ovum. At the moment of conception, when portions of the two nuclei of the copulating cells join together to form the nucleus of the stem-cell, the accompanying fragments of the immaterial souls must also be supposed to coalesce.

On this Dualistic view the phenomena of psychic development are totally incomprehensible. Everybody knows that the new-born child has no consciousness, no knowledge of itself and the surrounding world. Every parent who has impartially followed the mental development of his children will find it impossible to deny that it is a case of biological evolutionary processes. Just as all other functions of the body develop in connection with their organs, so the soul does in connection with the brain. This gradual unfolding of the soul of the child is, in fact, so wonderful and glorious a phenomenon that every mother or father who has eyes to observe is never tired of contemplating it. It is only our manuals of psychology that know nothing of this development; we are almost tempted to think sometimes that their authors can never have had children themselves. The human soul, as described in most of our psychological works, is merely the soul of a learned philosopher, who has read a good many books, but knows nothing of evolution, and never even reflects that his own soul has had a development.

When these Dualistic philosophers are consistent they must assign a moment in the phylogeny of the human soul at which it was first “introduced” into man’s vertebrate body. Hence, at the time when the human body was evolved from the anthropoid body of the ape (probably in the Tertiary period), a specific human psychic element—or, as people love to say, “a spark of divinity”—must have been suddenly infused or breathed into the anthropoid brain, and been associated with the ape-soul already present in it. I need not insist on the enormous theoretical difficulties of this idea. I will only point out that this “spark of divinity,” which is supposed to distinguish the soul of man from that of the other animals, must be itself capable of development, and has, as a matter of fact, progressively developed in the course of human history. As a rule, reason is taken to be this “spark of divinity,” and is supposed to be an exclusive possession of humanity. But comparative psychology shows us that it is quite impossible to set up this barrier between man and the brute. Either we take the word “reason” in the wider sense, and then it is found in the higher mammals (ape, dog, elephant, horse) just as well as in most men; or else in the narrower sense, and then it is lacking in most men just as much as in the majority of animals. On the whole, we may still say of man’s reason what Goethe’s Mephistopheles said:—

Life somewhat better might content him But for the gleam of heavenly light that Thou hast given him. He calls it reason; thence his power’s increased To be still beastlier than any beast.

If, then, we must reject these popular and, in some respects, agreeable Dualistic theories as untenable, because inconsistent with the genetic facts, there remains only the opposite or Monistic conception, according to which the human soul is, like any other animal soul, a function of the central nervous system, and develops in inseparable connection therewith. We see this ontogenetically in every child. The biogenetic law compels us to affirm it phylogenetically. Just as in every human embryo the skin-sense layer gives rise to the medullary tube, from the anterior end of which the five cerebral vesicles of the Craniotes are developed, and from these the mammal brain (first with the characters of the lower, then with those of the higher mammals); and as the whole of this ontogenetic process is only a brief, hereditary reproduction of the same process in the phylogenesis of the Vertebrates; so the wonderful spiritual life of the human race through many thousands of years has been evolved step by step from the lowly psychic life of the lower Vertebrates, and the development of every child-soul is only a brief repetition of that long and complex phylogenetic process. From all these facts sound reason must conclude that the still prevalent belief in the immortality of the soul is an untenable superstition. I have shown its inconsistency with modern science in the eleventh chapter of The Riddle of the Universe.

Here it may also be well to point out the great importance of anthropogeny, in the light of the biogenetic law, for the purposes of philosophy. The speculative philosophers who take cognizance of these ontogenetic facts, and explain them (in accordance with the law) phylogenetically, will advance the great questions of philosophy far more than the most distinguished thinkers of all ages have yet succeeded in doing. Most certainly every clear and consistent thinker must derive from the facts of comparative anatomy and ontogeny we have adduced a number of suggestive ideas that cannot fail to have an influence on the progress of philosophy. Nor can it be doubted that the candid statement and impartial appreciation of these facts will lead to the decisive triumph of the philosophic tendency that we call “Monistic” or “Mechanical,” as opposed to the “Dualistic” or “Teleological,” on which most of the ancient, medieval, and modern systems of philosophy are based. The Monistic or Mechanical philosophy affirms that all the phenomena of human life and of the rest of nature are ruled by fixed and unalterable laws; that there is everywhere a necessary causal connection of phenomena; and that, therefore, the whole knowable universe is a harmonious unity, a monon. It says, further, that all phenomena are due solely to mechanical or efficient causes, not to final causes. It does not admit free-will in the ordinary sense of the word. In the light of the Monistic philosophy the phenomena that we are wont to regard as the freest and most independent, the expressions of the human will, are subject just as much to rigid laws as any other natural phenomenon. As a matter of fact, impartial and thorough examination of our “free” volitions shows that they are never really free, but always determined by antecedent factors that can be traced to either heredity or adaptation. We cannot, therefore, admit the conventional distinction between nature and spirit. There is spirit everywhere in nature, and we know of no spirit outside of nature. Hence, also, the common antithesis of natural science and mental or moral science is untenable. Every science, as such, is both natural and mental. That is a firm principle of Monism, which, on its religious side, we may also denominate Pantheism. Man is not above, but in, nature.

It is true that the opponents of evolution love to misrepresent the Monistic philosophy based on it as “Materialism,” and confuse the philosophic tendency of this name with a wholly unconnected and despicable moral materialism. Strictly speaking, it would be just as proper to call our system Spiritualism as Materialism. The real Materialistic philosophy affirms that the phenomena of life are, like all other phenomena, effects or products of matter. The opposite extreme, the Spiritualistic philosophy, says, on the contrary, that matter is a product of energy, and that all material forms are produced by free and independent forces. Thus, according to one-sided Materialism, the matter is antecedent to the living force; according to the equally one-sided view of the Spiritist, it is the reverse. Both views are Dualistic, and, in my opinion, both are false. For us the antithesis disappears in the Monistic philosophy, which knows neither matter without force nor force without matter. It is only necessary to reflect for some time over the question from the strictly scientific point of view to see that it is impossible to form a clear idea of either hypothesis. As Goethe said, “Matter can never exist or act without spirit, nor spirit without matter.”

The human “spirit” or “soul” is merely a force or form of energy, inseparably bound up with the material substratum of the body. The thinking force of the mind is just as much connected with the structural elements of the brain as the motor force of the muscles with their structural elements. Our mental powers are functions of the brain as much as any other force is a function of a material body. We know of no matter that is devoid of force, and no forces that are not bound up with matter. When the forces enter into the phenomenon as movements we call them living or active forces; when they are in a state of rest or equilibrium we call them latent or potential. This applies equally to inorganic and organic bodies. The magnet that attracts iron filings, the powder that explodes, the steam that drives the locomotive, are living inorganics; they act by living force as much as the sensitive Mimosa does when it contracts its leaves at touch, or the venerable Amphioxus that buries itself in the sand of the sea, or man when he thinks. Only in the latter cases the combinations of the different forces that appear as “movement” in the phenomenon are much more intricate and difficult to analyse than in the former.

Our study has led us to the conclusion that in the whole evolution of man, in his embryology and in his phylogeny, there are no living forces at work other than those of the rest of organic and inorganic nature. All the forces that are operative in it could be reduced in the ultimate analysis to growth, the fundamental evolutionary function that brings about the forms of both the organic and the inorganic. But growth itself depends on the attraction and repulsion of homogeneous and heterogeneous particles. Seventy-five years ago Carl Ernst von Baer summed up the general result of his classic studies of animal development in the sentence: “The evolution of the individual is the history of the growth of individuality in every respect.” And if we go deeper to the root of this law of growth, we find that in the long run it can always be reduced to that attraction and repulsion of animated atoms which Empedocles called the “love and hatred” of the elements.

Thus the evolution of man is directed by the same “eternal, iron laws” as the development of any other body. These laws always lead us back to the same simple principles, the elementary principles of physics and chemistry. The various phenomena of nature only differ in the degree of complexity in which the different forces work together. Each single process of adaptation and heredity in the stem-history of our ancestors is in itself a very complex physiological phenomenon. Far more intricate are the processes of human embryology; in these are condensed and comprised thousands of the phylogenetic processes.

In my General Morphology, which appeared in 1866, I made the first attempt to apply the theory of evolution, as reformed by Darwin, to the whole province of biology, and especially to provide with its assistance a mechanical foundation for the science of organic forms. The intimate relations that exist between all parts of organic science, especially the direct causal nexus between the two sections of evolution—ontogeny and phylogeny—were explained in that work for the first time by transformism, and were interpreted philosophically in the light of the theory of descent. The anthropological part of the General Morphology (Book 7) contains the first attempt to determine the series of man’s ancestors (volume 2 page 428). However imperfect this attempt was, it provided a starting-point for further investigation. In the thirty-seven years that have since elapsed the biological horizon has been enormously widened; our empirical acquisitions in paleontology, comparative anatomy, and ontogeny have grown to an astonishing extent, thanks to the united efforts of a number of