Homo Sapiens

From Man to Demigod

Bernhard Rensch

• Publisher: Routledge
• Year: 2019
• Print ISBN: 9780367278670
• eBook ISBN: 9781000063813
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Originally published in 1972, Homo Sapiens examines how humans emerged from among the millions of other species and achieved our unique position within the animal kingdom. The book examines what direction future evolution will take and what may be regarded as the 'meaning' of human existence. It stipulates that these are the questions for which no real basis of discussion existed before the 20th century, and at the time of publication, some were still without a definite answer. The book sets out analyse these questions and the continuing debate that has arisen from their study. This is an account of the uniqueness of man in the animal kingdom, how this uniqueness arose during evolution, and what traces of it can be detected in animals other than man. The book describes the mental and physical evolution of man, from his earliest ancestors to the present day. He also gives an account of man's cultural development seeking to establish that there is an underlying principal of cultural evolution, a principle that has been denied by many historians. Later chapters deal with the future and with possible forecasts of mankind's further physical, intellectual and cultural evolution.

CHAPTER ONE

The problem of man

What are we, we humans? How did we come to be on this planet? Where is our history leading us? Man has been asking these questions ever since he has become aware of himself, created a culture and grown up within a framework of stable tradition. The answers have varied enormously at different epochs and with different peoples. Those with an animistic faith see man as similar in kind to the animals, even as directly derived from animals species. To Hindus and Buddhists he is an incarnation of the eternal principle of life, which journeys through various stages (perhaps including animal ones) until at last it merges in the brahman, the universal soul, or the Nirvana. Jews and Christians believe man to have been created by the finger of God and formed in his image. Today, those with a scientific training recognize that he is descended from animal ancestors and that his unique cerebral development has made him the first, and only, creature with creative power and a sense of values. Most Christian theologians have recently accepted this view in a more liberal interpretation of the Book of Genesis.

But how was it that Homo sapiens emerged from among the millions of other species? How did he achieve his unique position among the higher animals, which he resembles so much in physique? What direction will his future evolution take? What may be regarded as the ‘meaning’ of his existence? These are questions for which no real basis of discussion existed before the present century; and today some of them are still without a definite answer.

Our own age is one that particularly calls for reflection on these elementary problems of existence. Undoubtedly man’s cultural development has today reached an important turning-point. Within the last decades he has immeasurably expanded and deepened his knowledge of the structure of the universe, of matter, molecules, atoms, elementary particles and radiation, as well as his knowledge about the nature of life and the development of mental processes. All this has formed the basis for expanding technical skills, which have already made drastic alterations in our way of life, and will continue to do so. Atomic energy is being harnessed and is beginning to affect our lives profoundly; our electronic computers can solve technical and theoretical problems of a complexity greater than anything tackled by mathematicians before. Space research has opened up entirely new prospects. The separate achievements ofleading nations are fusing into a universal culture; and this culture is expanding at an immense pace, now that all sections of their populations are able to rise to higher social levels – and especially as the backward countries are making spectacular strides towards a more advanced civilization.

We can now offer at least a partial answer to these questions of man’s origin, biological uniqueness and possible future development; and they involve such important considerations and open up possibilities of such consequence that it is the duty of every cultured individual to have some measure of aquaintance with them. The essentials of man’s phylogeny are vouched for by a wealth of material, and the literature on the subject is immense. So too is the number of publications on the problem of man’s separate existence – though these vary enormously according to whether their authors are biologists, historians, philosophers or theologians. An abundance of Utopian novels, stories and plays, deal with future possibilities, while specific problems, mostly biological, sociological and economic, now begin to receive rather more scientific treatment.

The present work makes no attempt to enumerate and assess this huge mass of writings. Its aim is rather to see the whole complex of questions from a coherent point of view, with special consideration of findings which may help to throw some new light. Observations will be based as far as possible on factual material drawn especially from the fields of palaeontology, comparative psychology and cultural history.

The first task will be to determine how and why any progressive phylogenetic development of living organisms took place on this planet, and what in particular led to the emergence of man in his present form. We shall consider how the human mind emerged from earlier animal stages. With the rise and progress of cultures we shall have to sketch the outlines of man’s strange and unique position, touching on certain imperfections and various dangers in the path of his future evolution. We shall see that although it springs from an entirely different root the rise of man’s culture has been subject to similar laws and constraints to those that have governed the evolution of other living organisms. The fact of these far-reaching parallels has largely escaped notice so far, and indeed many historians deny that there is any system of laws underlying the course of historical events. In my view, however, it is most important to recognize these constraints; we shall then be able to attempt a cautious forecast of the future development of man’s specifically human characteristics, as well as to outline a clear-cut aim -namely, a rather more purposive progressive development of man’s special features and a more consistent direction of his cultural future. Naturally enough, this can only be expressed with some caution; but in view of the vast theoretical and practical importance of the problems, it must be attempted. For the steady advance of science teaches us not only the constant need for a critical outlook; it also sanctions unshakeable optimism about such aims as are attainable.

The ensuing chapters will be concerned with biological, psychological and cultural facts. But, as we have said, we shall always lay particular stress on the data that are capable of proof rather than on more or less arresting phrases. By so doing we hope to escape the criticism expressed by the astute late-eighteenth-century cynic G. C. Lichtenberg: ‘If we think of Nature as our teacher and poor mankind as her hearers, we tend to arrive at a strange idea of the human race. Here we sit together in a Collegio, with all the faculties necessary to understand and appreciate what is said; but we are constantly listening more to the chatter of our companions than the words of our instructress.’

CHAPTER TWO

Man’s physical evolution

A. The stream of life

On the evidence of the many subfossil and fossil remains of human skeletons it is safe to say that Homo sapiens, man as we know him today, came into being towards the end of the Pleistocene epoch, in all probability no more than 100,000 years ago. The line of his ancestry quite clearly leads back to apes. The late Phiocene and early Pleistocene South African Australopithecines, standing midway between animals and man, make this abundantly plain. At first these Australopithecines were taken to be highly advanced anthropoid apes (‘super-chimpanzees’)’, but after the discovery of more fossil material they were ranked as ‘still’ belonging to the Hominidae, though this has meant considerably extending the characteristics of that family. In 1953 G. H. R. von Koenigswald [118] expressed the uncertainties of classification when he described the Australopithecines as an ‘animal manifestation of man’, which had not yet advanced beyond the animal stage. At present anthropologists are more and more inclined to consider these types as a basic branch of the human family tree.

It is certain that man is descended from the Old World (Catarrhine) monkeys, which in turn derive from early Tertiary lemurs (Tarsioidea). The line of ancestry can be traced further back through the insectivores and primitive mammals to mammal-like reptiles (the Theriodontidae of Upper Triassic), to primitive reptiles (the Cotylosaurs of the Carboniferous), to Amphibia (early Devonian) and to the earliest jawless fish (the Agnatha of the Ordovician). On all these phylogenetic levels anatomical and physiological characteristics arose that represented an advantage (see below). They were retained and improved during phylogeny, right up to the emergence of present-day man. In order to understand man as a biological phenomenon, we must examine in turn the main structural advances at each stage in his animal ancestry.

This involves going still further back. The phylogenetic tree just outlined, which is based in general upon fossil material, begins with the earliest of all fish, the jawless Agnatha. It is impossible to say exactly from what earlier animal stages these most primitive vertebrates derive. Such creatures, having in all probability no bony skeleton, could hardly leave fossilized traces. Studies in comparative anatomy, however, and in comparative embryology, show that the ancestors of the vertebrates were probably similar in structure to the existing ‘lancelets’ (Branchiostoma – headless and limbless invertebrates). We cannot be positive, but it is likely that these Acrania are in turn descended from certain groups of worm-like Hemichordata. We may further assume that all the higher animal groups derive primarily from protozoa. These single-celled organisms already have many features which are retained in multicellular animals, including the mammals and man himself (proteins and nucleic acids forming the most important building blocks, cell nuclei containing chromosomes, mitosis as the precise mechanism of nuclear division, cytoplasm, mitochondria, and so on).

We must also give at least brief consideration to the question of the genesis of life itself, because man still retains some characteristics that originated at this stage, which are of importance in typically ‘human’ problems. The exact nature of life has not yet been fully explained, but we already know a good deal about it. Intensive study of many structures and processes typical of living organisms have at least established that we no longer need to trace life back to mysterious ‘biogenetic molecules’ absent in inanimate matter, or to the influence of vital forces (what H. Driesch termed ‘entelechies’) that defy analysis. On the contrary, living organisms are composed of the self-same molecules and atoms that are found in inanimate substances. The living substance, in all its activities, is continually taking in and excreting those molecules and atoms. Every vital function (not taking the phenomenon of consciousness into account here) derives originally from physico-chemical processes. It is thus possible to state the problem of life in terms of the following questions: (1) How could a system of organic molecules, capable of identical reduplication, develop and remain more or less constant over a long period? (2) How can one explain the further evolution of this living substance into more complex organisms? (3) How can more complex organisms, made up of many diverse substances, continue to take in and excrete inanimate matter and yet remain constant with regard to their individual cycle of development (as for instance from the ovum to the adult individual) in spite of the law of entropy?

It is not yet possible to give a complete answer to all the problems raised here; but an extremely varied stock of facts in the spheres of biochemistry, physiology, genetics and evolution enables us to give a positive reply to many important points, and a very probable one to others [8, 26, 30, 40, 44, 46, 61, 72, 84, 98, 99, 121, 146, 148, 151, 164, 169, 181, 196, 199, 205, 242].

The first beginnings of life inaugurated processes that were to affect every organism up to man himself. Most recently it has seemed increasingly probable that life came gradually into being. The vital factor in this evolution was the development of proteins, allowing very complicated and manifold chemical processes, and of special nucleic acids, substances capable of identical reduplication forming the basis for reproduction, heredity, and long-term stability of the organism – in other words for the continuance of life. The development of these and other complicated organic compounds seems to be possible, because it is possible to prove that they could have originated under prebiological conditions, after the solid surface of the earth had been formed (cf. section D of this chapter).

It is this same process of reduplication that has produced every new generation of living organisms and their prestages. From the earliest stage the principle has held good that life springs from life. The axiom, omne vivum e vivo, established in the seventeenth century and confirmed by Pasteur’s classic experiments in 1862 [170], has invariably proved to be true. Among animals and plants, among protozoa and multicellular organisms, no completely new individual has ever sprung into being; each has always developed out of the germ cells or out of somatic cells of previous generations, or protozoa have divided into two or more units. In other words, life flows on in a continuous stream, an uninterrupted chain of self-dividing cells. Among multicellular organisms, including man, the succeeding generations form a chain of individual life cycles linked together by the continuity of the germ cells or other ‘totipotent’ cells. In most cases the ovum is at first fertilized by a sperm; then, by cell division and the subsequent differentiation of certain groups of cells to form tissues and organs, the adult individual gradually emerges. One group of cells, the germ cells, is always set aside within each individual. Since their future development is unimpaired by specialization, they remain ‘totipotent’. This succession of immature and mature germ cells emerging one from the other, this ‘germ tract’, constitutes the real unbroken thread of life. The individuals, growing and adult, strung along its length, form specialized cell complexes whosestructures and physiological processes help to ensure its continuance (Fig. 1). Our chief concern, of course, is with these ‘outgrowths’, these actual individuals, whether plants, animals or humans [181, 196].

Fig. 1 The germ tract, the continuous chain of immature and mature sex cells, linking the generations in an unbroken thread of life. Dots indicate germ cells in the embryo and adult.

Each individual normally produces several offspring. Therefore the stream of life regularly divides and branches out. Some branches, however, undergo alterations by mutations and new gene combinations, and the most favourable to the relevant environment are perpetuated, while unfavourable ones are eliminated. Yet however diverse the forms that gradually emerge in this way may be – new races, species, genera, families and classes – the categories are all branches of the same single ancestral tree. It is of prime importance for us to grasp this point if we are to come to an understanding of ourselves as human beings. All that is and was alive is a unity in that it is homogeneous in its origin and its continued growth; it branches out down the ages like a tree whose sole growing points at any given time are the countless living organisms representing the tips of its outermost twigs. This means that all organisms are genuinely related to one another, for they share common ancestors with whom they are linked in substance through an unbroken tract.

As individuals transmit life by the identical reduplication of nucleic acid threads, and hence of the germ cells, in each succeeding generation more and more individuals come into being. A dividing unicellular organism increases in number by geometrical progression: from 2 to 4, 8, 16, 32 and so on. This rapidly leads to a number of individuals which outruns the space and food available. Many are bound to perish. Competition occurs, and natural selection more or less eliminates the less favourable variants. At all levels of life, even the lowest, this undue increase has always led to the danger of overpopulation. So, the human race, threatened by the same danger, is suffering an affliction as old as life itself.

B. Factors and laws determining the phylogeny of animals and man

It is probable that the identical reduplication of the nucleic acids, and the proteins they synthesize, represents the first decisive stage in the emergence of life. We have already noted that in the prestages of organisms these factors have led to a high degree of stability, though mutation keeps it from being complete. Later, as mutation and natural selection involved greater and greater complexity, leading to real organisms, it was vital that the structure of the whole life cycle (from the germ cell to the adult) should remain stable over long periods. If each generation had differed essentially from the one before, life could not have survived, because the conditions under which subsistence and reproduction were possible for a particular organism were always limited. Heredity, then, is a necessary factor in the devel...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Title Page
• Original Copyright Page
• Dedication
• Contents
• Preface
• Chapter 1 The problem of man
• Chapter 2 Man’s physical evolution
• Chapter 3 Man’s mental evolution
• Chapter 4 Biological aspects of man’s cultural development
• Chapter 5 The biological uniqueness of man
• Chapter 6 The future of mankind
• Chapter 7 Sub specie aeternitatis
• References and Bibliography
• Short Glossary of Technical Terms
• Index