 Section 9 of the Outline of Science, Volume 1 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recorded by Laurie-Ann Walden. The Outline of Science, Volume 1 by J. Arthur Thompson. Section 9. Part 5 The Ascent of Man Continued. 4. Tentative Men. So far the story has been that of the sifting out of a humanoid stock and of the transition to humankind from the ancestors of apes and men to the man ape and from the man ape to man. It looks as if the sifting out process had proceeded further for there were several human branches that did not lead on to the modern type of man. 1. The first of these is represented by the scanty fossil remains known as Pythicanthropus erectus found in java and fossiliferous beds which date from the end of the Pliocene or the beginning of the Pliostocene era. Perhaps this means half a million years ago and the remains occurred along with those of some mammals which are now extinct. Unfortunately the remains of Pythicanthropus the erect consisted only of a skullcap, a thighbone, and two back teeth. So it is not surprising that experts should differ considerably in their interpretation of what was found. Some have regarded the remains as those of a large gibbon, others as those of a pre-human ape man, and others as those of a primitive man off the main line of ascent. According to Sir Arthur Keith Pythicanthropus was a being human in stature, human in gait, human in all its parts, save its brain. The thighbone indicates a height of about five feet seven inches, one inch less than the average height of the men of today. The skullcap indicates a low flat forehead, beatling brows, and a capacity about two thirds of the modern size. The remains were found by Dubois in 1894 in Trinil in central Java. Two, the next offshoot is represented by the Heidelberg man, Homo Heidelbergensis, discovered near Heidelberg in 1907 by Dr. Schutensack. But the remains consisted only of a lower jaw and its teeth. Along with this relic were bones of various mammals, including some long since extinct in Europe such as elephant, rhinoceros, bison, and lion. The circumstances indicate an age of perhaps 300,000 years ago. There were also very crude flint implements, or eliths. But the teeth are human teeth, and the jaw seems transitional between that of an anthropoid ape and that of man. Thus there was no chin. According to most authorities, the lower jaw from the Heidelberg sand-fit must be regarded as a relic of a primitive type off the main line of human ascent. Three, it was in all probability in the Pliocene that there took origin the Neanderthal species of man, Homo Neanderthalensis, first known from remains found in 1856 in the Neanderthal ravine near Dusseldorf. According to some authorities, Neanderthal man was living in Europe a quarter of a million years ago. Other specimens were afterwards found elsewhere, e.g. in Belgium, the men of Spie, in France, in Croatia, and at Gibraltar, so that a good deal is known of Neanderthal man. He was a loose-limbed fellow short of stature and of slouching gait, but a skillful artificer fashioning beautifully worked flints with a characteristic style. He used fire, he buried his dead reverently and furnished them with an outfit for a long journey, and he had a big brain. But he had great beetling, ape-like eyebrow ridges, and massive jaws, and he showed semean characters swarming in the details of his structure. And most of the points in which he differs from modern man, he approaches the anthropoid apes, and he must be regarded as a low type of man off the main line. Huxley regarded the Neanderthal man as a low form of the modern type, but expert opinion seems to agree rather with the view maintained in 1864 by Professor William King of Galway, that the Neanderthal man represents a distinct species off the main line of ascent. He disappeared with apparent suddenness, like some aboriginal races today, about the end of the Fourth Great Ice Age. But there is evidence that before he ceased to be there had emerged a successor rather than a descendant, the modern man. Four. Another offshoot from the main line is probably represented by the Piltdown man, found in Sussex in 1912. The remains consisted of the walls of the skull, which indicate a large brain, and a high forehead without the beetling eyebrows of the Neanderthal man and pithicanthropus. The find included a tooth and part of a lower jaw, but these perhaps belong to some ape, for they are very discrepant. The Piltdown skull represents the most ancient human remains as yet found in Britain, and Dr. Smith Woodward's establishment of a separate genus Eoanthropus expresses his conviction that the Piltdown man was off the line of the evolution of the modern type. If the tooth and piece of lower jaw belonged to the Piltdown skull, then there was a remarkable combination of ape-like and human characters. As regards the brain, inferred from the skull walls, Sir Arthur Keith says, All the essential features of the brain of modern man are to be seen in the braincast. There are some which must be regarded as primitive. There can be no doubt that it is built on exactly the same lines as our modern brains. A few minor alterations would make it in all respects a modern brain. Although our knowledge of the human brain is limited, there are large areas to which we can assign no definite function. We may rest assured that a brain which was shaped in a mold so similar to our own was one which responded to the outside world as ours does. Piltdown man saw, heard, felt, thought, and dreamt much as we do still. And this was one hundred and fifty thousand years ago at a modern estimate, and some would say half a million. There is neither agreement nor certainty as to the antiquity of man, except that the modern type was distinguishable from its collateral hundreds of thousands of years ago. The general impression left is very grand. In remote antiquity the primate stem diverged from the other orders of mammals. It sent forth its tentative branches, and the result was a tangle of monkeys. Ages passed and the monkeys were left behind, while the main stem, still probing its way, gave off the anthropoid apes both small and large. But they too were left behind and the main line gave off other experiments, indications of which we know in Java, at Hodelberg, in the Neanderthal, and at Piltdown. None of these lasted or was made perfect. They represent tentative men who had their day and ceased to be, our predecessors rather than our ancestors. Still the main stem goes on evolving, and who will be bold enough to say what fruit it has yet to bear? Primitive men. Ancient skeletons of men of the modern type have been found in many places, e.g., kum kapel in Dordon, Galley Hill in Kent, Co-Magnon in Paragord, Mentone on the Riviera, and they are often referred to as cave men, or men of the early Stone Age. They had large skulls, high foreheads, well-marked chins, and other features such as modern man possesses. They were true men at last, that is to say, like ourselves. The spirited pictures they made on the walls of caves in France and Spain show artistic sense and skill. Well-finished statuettes representing nude female figures are also known. The elaborate burial customs point to a belief in life after death. They made stone implements, knives, scrapers, gravers, and the like of the type known as paleolithic, and these show interesting gradations of skill and peculiarities of style. The cavemen lived between the Third and Fourth Ice Ages, along with cave bear, cave lion, cave hyena, mammoth, woolly rhinoceros, Irish elk, and other mammals now extinct, taking us back to 30,000 to 50,000 years ago, and many would say much more. Some of the big-brained skulls of these paleolithic cavemen show not a single feature that could be called primitive. They show teeth which in size and form are exactly the same as those of a thousand generations afterwards, and suffering from gum boil, too. There seems a little doubt that these vigorous paleolithic cavemen of Europe were living for a while contemporaneously with the men of Neanderthal, and it is possible that they directly or indirectly hastened the disappearance of their more primitive collaterals. Curiously enough, however, they had not themselves adequate lasting power in Europe, for they seemed for the most part to have dwindled away, leaving perhaps stray present-day survivors in isolated districts. The probability is that after their decline Europe was re-peopled by immigrants from Asia. It cannot be said that there is any inherent biological necessity for the decline of a vigorous race. Many animal races go back for millions of years, but in mankind the historical fact is that a period of great racial vigor and success is often followed by a period of decline, sometimes leading to practical disappearance as a definite race. The causes of this waning remain very obscure, sometimes environmental, sometimes constitutional, sometimes competitive. Sometimes the introduction of a new parasite, like the malaria organism, may have been to blame. After the Ice Ages had passed, perhaps twenty-five thousand years ago, the Paleolithic culture gave place to the Neolithic. The men who made rudely dressed but often beautiful stone implements were succeeded or replaced by men who made polished stone implements. The earliest inhabitants of Scotland were of this Neolithic culture, migrating from the continent when the ice fields of the Great Glaciation had disappeared. Their remains are often associated with the fifty-foot beach, which, though now high and dry, was the seashore in early Neolithic days. Much is known about these men of the polished stones. They were hunters, fowlers, and fishermen, without domesticated animals or agriculture. Short folk, two or three inches below the present standard, living an active, strenuous life. Similarly, for the South, Sir Arthur Keith pictures for us a Neolithic community at Culdrum in Kent, dating from about four thousand years ago, a few ticks of the geological clock. It consisted in this case of agricultural pioneers, men with large heads and big brains, about two inches shorter in stature than the modern British average, five feet eight inches, with better teeth and broader pallets than men have in these days of soft food, with beliefs concerning life and death similar to those that swayed their contemporaries in western and southern Europe. Very interesting is the manipulative skill they showed on a large scale in erecting standing stones, probably connected with calendar keeping and with worship, and on a small scale in making daring operations on the skull. Four thousand years ago is given as a probable date for that early community in Kent, but evidences of Neolithic man occur in situations which demand a much greater antiquity, perhaps thirty thousand years, and man was not young then. We must open one more chapter in the thrilling story of the Ascent of Man, the metal ages, which are in a sense still continuing. Metals began to be used in the late polished stone, Neolithic times, for there were always overlappings. Copper came first, bronze second, and iron last. The working of copper in the east has been traced back to the fourth millennium BC, and there was also a very ancient copper age in the New World. It need hardly be said that where copper is scarce, as in Britain, we cannot expect to find much trace of a copper age. The ores of different metals seem to have been smelted together in an experimental way by many prehistoric metallurgists, and bronze was the alloy that rewarded the combination of tin with copper. There is evidence of a more or less definite bronze age in Egypt and Babylonia, Greece, and Europe. It is not clear why iron should not have been the earliest metal to be used by man, but the iron age dates from about the middle of the second millennium BC. From Egypt the usage spread through the Mediterranean region to north Europe, or it may have been that discoveries made in central Europe, so rich in iron mines, saturated southwards, following, for instance, the root of the amber trade from the Baltic. Compared with stone, the metals afforded much greater possibilities of implements, instruments, and weapons, and their discovery in usage had undoubtedly great influence on the Ascent of Man. Occasionally, however, on his descent. Retrospect. Looking backwards we discern the following stages. 1. The setting apart of a primate stock marked off from other mammals by a tendency to big brains, a free hand, gregariousness, and good-humored talkativeness. 2. The divergence of marmosets and new world monkeys and old world monkeys, leaving a stock, an anthropoid stock, common to the present day and extinct apes and to mankind. 3. From this common stock the anthropoid apes diverged far from ignoble creatures and a humanoid stock was set apart. 4. From the latter we follow Sir Arthur Keith and other authorities. 5. There arose what may be called without disparagement, tentative or experimental men, indicated by Pythicanthropus the erect, the Heidelberg man, the Neanderthalers, and, best of all, the early men of the Sussex wheeled, hinted at by the Piltdown skull. It matters little whether particular items are corroborated or disproved, e.g. whether the Heidelberg man came before or after the Neanderthalers, the general trend of evolution remains clear. 5. In any case the result was the evolution of Homo sapiens, the man we are, a quite different fellow from the Neanderthaler. 6. Then arose various stocks of primitive men, proving everything and holding fast to that which is good. These were the Paleolithic peoples with rude stone implements, a strong vigorous race, but probably, in most cases, supplanted by fresh experiments. These may have arisen as shoots from the growing point of the old race, or as a fresh offshoot from more generalized members at a lower level. This is the eternal possible victory alike of aristocracy and democracy. 7. Paleolithic men were involved in the succession of four great ice ages, or glaciations, and it may be that the human race owes much to the alternation of hard times and easy times, glacial and interglacial. When the ice field cleared off, Neolithic man had his innings. 8. And we have closed the story in the meantime with the metal ages. 9. It seems not unfitting that we should at this point sound another note, that of the man of feeling. It is clear in William James's words. 10. Bone of our bone and flesh of our flesh are these half-British prehistoric brothers, girdled about with the immense darkness of this mysterious universe even as we are, they were born and died, suffered and struggled. 11. Given over to fearful crime and passion, plunged in the blackest ignorance, preyed upon by hideous and grotesque delusions, yet steadfastly serving the profoundest of ideals in their fixed faith that existence in any form is better than non-existence. 12. They ever rescued triumphantly from the jaws of ever-eminent destruction the torch of life, which, thanks to them, now lights the world for us. 13. Races of mankind Given a variable stock spreading over diverse territory, we expect to find it splitting up into varieties which may become steadied into races or incipient species. Thus we have races of hive bees, Italians, punyx, and so forth, and thus there arose races of men. 14. Certain types suited certain areas, and periods of inbreeding tended to make the distinctive peculiarities of each incipient race well-defined and stable. 15. When the original peculiarities, say, of Negro and Mongol, Australian and Caucasian, arose as brusque variations or mutations, then they would have great staying power from generation to generation. 16. They would not be readily swamped by intercrossing or averaged off. 17. Peculiarities and changes of climate and surroundings, not to speak of other change-producing factors, would provoke new departures from age to age, and so fresh racial ventures were made. 18. Moreover the occurrence of outbreeding when two races met, in peace or in war, would certainly serve to induce fresh starts. 19. Very important in the evolution of human races must have been the alternating occurrence of periods of inbreeding, endogamy, tending to stability and sameness, and periods of outbreeding, exogamy, tending to changefulness and diversity. 20. Thus we may distinguish several more or less clearly defined primitive races of mankind, notably the African, the Australian, the Mongolian, and the Caucasian. 21. The woolly-haired African race includes the Negroes and the very primitive Bushmen. 22. The wavy to curly-haired Australian race includes the jungle tribes of the Deccan, the Veta of Salon, the jungle folk or Samang, and the natives of unsettled parts of Australia, all sometimes slumped together as pre-Dravidians. 23. The straight-haired Mongols include those of Tibet, Indochina, China, and Formosa, those of many oceanic islands, and of the North from Japan to Lapland. 24. The Caucasians include Mediterranean, Semites, Nordics, Afghans, Alpines, and many more. 25. There are very few corners of knowledge more difficult than that of the races of men, the chief reason being that there has been so much movement and migration in the course of the ages. 26. One physical type has mingled with another, inducing strange amalgams and novelties. 27. If we start with what might be called zoological races, or strange differing, for instance, in their hair, woolly-haired Africans, straight-haired Mongols, curly or wavy-haired pre-Dravidians, and Caucasians, we find these replaced by peoples who are mixtures of various races, brethren by civilization more than by blood. 28. As Professor Flinders Petrie has said, the only meaning the term race now can have is that of a group of human beings whose type has been unified by their rate of assimilation, exceeding the rate of change produced by the infiltration of foreign elements. 29. It is probable, however, that the progress of precise anthropology will make it possible to distinguish the various racial strains that make up any people. 30. For the human sense of race is so strong that it convinces us of reality even when scientific definition is impossible. 31. It was this the British sailor expressed in his answer to the question, what is a dago? 32. Dago's, he replied, is anything what isn't our sort of chaps. 33. Steps in human evolution 34. Real men arose, we believe, by variational uplifts of considerable magnitude which led to big and complex brains and to the power of reasoned discourse. 35. In some other lines of mammalian evolution there were, from time to time, great advances in the size and complexity of the brain, as is clear, for instance, in the case of horses and elephants. 36. The same is true of birds as compared with reptiles, and everyone recognizes the high level of excellence that has been attained by their vocal powers. 37. How these great cerebral advances came about we do not know, but it has been one of the main trends of animal evolution to improve the nervous system. 38. Two suggestions may be made. First, the prolongation of the period of antenatal life, an intimate physiological partnership with the mother, may have made it practicable to start the higher mammal with a much better brain than in the lower orders, like insectivores and rodents, and still more marsupials, where the period before birth, gestation, is short. 39. Second, we know that the individual development of the brain is profoundly influenced by the internal secretions of certain ductless glands, notably the thyroid. 40. When this organ is not functioning properly the child's brain development is arrested. It may be that increased production of certain hormones, itself of course to be accounted for, may have stimulated brain development in manned remote ancestors. 41. Given variability along the line of better brains, and given a process of discriminant sifting which would consistently offer rewards to alertness and foresight, to kin sympathy and parental care, there seems no great difficulty in imagining how man would evolve. 42. We must not think of an Aristotle or a Newton except as fine results which justify all the groaning and travailing. We must think of average men, of primitive peoples today, and of our forebears long ago. We must remember how much of man's advance is dependent on the external registration of the social heritage, not on the slowly changing natural inheritance. 43. Looking backwards it is impossible, we think, to fail to recognize progress. There is a ring of truth in the fine description Escalus gave of primitive men that, first, beholding they beheld in vain, and hearing, heard not, but like shapes and dreams, mixed all things wildly down the tedious time, nor knew to build a house against the sun with wickeded sides, nor any woodwork new, but lived like silly ants beneath the ground in hollow caves unsunned. There came to them no steadfast sign of winter, nor of spring flower perfumed, nor of summer full of fruit, but blindly and lawlessly they did all things. 44. Contrast this picture with the position of man today. He has mastered the forces of nature and is learning to use their resources more and more economically. He has harnessed electricity to his chariot, and he has made the ether carry his messages. He taps supplies of material which seemed for centuries unavailable, having learned, for instance, how to capture and utilize the free nitrogen of the air. With his telegraph and wireless he has annihilated distance, and he has added to his navigable kingdom the depths of the sea and the heights of the air. He has conquered one disease after another, and the young science of heredity is showing him how to control in his domesticated animals and cultivated plants the nature of the generations yet unborn. With all his faults he has his ethical face set in the right direction. The main line of movement is towards the fuller embodiment of the true, the beautiful, and the good, and healthy lives which are increasingly a satisfaction in themselves. Factors in human progress. Many, we believe, were the gains that rewarded the arboreal apprenticeship of man's ancestors. Many likewise were the results of leaving the trees and coming down to the solid earth, a transition which marked the emergence of more than tentative men. What great steps followed. Some of the greatest were the working out of a spoken language and of external methods of registration, the invention of tools, the discovery of the use of fire, the utilization of iron and other metals, the taming of wild animals such as dog and sheep, horses and cattle, the cultivation of wild plants such as wheat and rice, and the irrigation of fields. All through the ages necessity has been the mother of invention and curiosity its father, but perhaps we miss the heart of the matter if we forget the importance of some leisure time wherein to observe and think. If our earth had been so clouded that the stars were hidden from men's eyes the whole history of our race would have been different. For it was through his leisure time observations of the stars that early man discovered the regularity of the year and got his fundamental impressions of the order of nature on which all his science is founded. If we are to think clearly of the factors of human progress we must recall the three great biological ideas, the living organism, its environment, and its functioning. For man these mean, one, the living creature, the outcome of parents and ancestors, a fresh expression of a bodily and mental inheritance. Two, the surroundings, including climate and soil, the plants and animals these allow. And three, the activities of all sorts, occupations and habits, all the actions and reactions between man and his milieu. In short, we have to deal with folk, place, work, the famil, lou, travail of the Laplace school. As to folk, human progress depends on intrinsic racial qualities, notably health and vigor of body, clearness and alertness of mind, and an indispensable sociality. The most powerful factors in the world are clear ideas in the minds of energetic men of good will. The differences in bodily and mental health, which mark races and stocks within a people, just as they mark individuals, are themselves traceable back to germinal variations or mutations and to the kind of sifting to which the race or stock has been subjected. Easygoing conditions are not only without stimulus to new departures, they are without the sifting which progress demands. As to place, it is plain that different areas differ greatly in their material resources and in the availability of these. Moreover, even when abundant material resources are present, they will not make for much progress unless the climate is such that they can be readily utilized. Indeed, climate has been one of the great factors in civilization, here stimulating and there depressing energy, in one place favoring certain plants and animals important to man, in another place preventing their presence. Moreover, climate has slowly changed from age to age. As to work, the form of a civilization is in some measure dependent on the primary occupations, whether hunting or fishing, farming or shepherding, and on the industries of later ages which have a profound molding effect on the individual at least. We cannot, however, say more than that the factors of human progress have always had these three aspects, folk, place, work, and that if progress is to continue on stable lines it must always recognize the essential correlation of fitter folk and body and mind, improved habits and functions, alike in work and leisure, and bettered surroundings in the widest and deepest sense. End of Section 9 Section 10 of The Outline of Science, Volume 1. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Leon Meyer. The Outline of Science, Volume 1 by J. Arthur Thompson. Section 10. Part 6. Evolution Going On. Evolution, as we have seen in a previous chapter, is another word for race history. It means the ceaseless process of becoming, linking generation to generation of living creatures. The doctrine of evolution states the fact that the present is the child of the past and the parent of the future. It comes to this that the living plants and animals we know are descended from ancestors on the whole simpler, and these from others likewise simpler, and so on, back and back, till we reach the first living creatures, of which unfortunately we know nothing. Evolution is a process of racial change in a definite direction, whereby new forms arise, take root, and flourish, alongside of or in the place of their ancestors, which were in most cases rather simpler in structure and behavior. The rock record, which cannot be wrong, though we may read it wrongly, shows clearly that there was once a time in the history of the earth when the only backboneed animals were fishes. Ages passed, and there evolved amphibians with fingers and toes, scrambling onto dry land. Ages passed, and there evolved reptiles in bewildering profusion. There were fish lizards and sea serpents, terrestrial dragons and flying dragons, a prolific and varied stock. From the terrestrial dinosaurs it seems that birds and mammals arose. In succeeding ages there evolved all the variety of birds and all the variety of mammals, until at last arose the man. The question is whether similar processes of evolution are still going on. We are so keenly aware of rapid changes in mankind, though these concern the social heritage much more than the flesh and blood natural inheritance, that we find no difficulty in the idea that evolution is going on in mankind. We know the contrast between modern man and primitive man, and we are convinced that in the past at least progress has been a reality. That degeneration may set in is an awful possibility, involution rather than evolution. What even if going back became for a time the rule, we cannot give up the hope that the race would recover itself and begin afresh to go forward. For although there have been retrogressions in the history of life continued through unthinkably long ages, and although great races, the flying dragons for instance, have become utterly extinct, leaving no successors whatsoever, we feel sure that there has been on the whole a progress towards nobler, more masterful, more emancipated, more intelligent, and better forms of life. A progress toward what mankind at its best has always regarded as best, i.e., affording most enduring satisfaction. So we think of evolution going on in mankind, evolution checkered by involution, but on the whole progressive evolution. Evolutionary prospect for man. It is not likely that man's body will admit of great change, but there is room for some improvement, e.g., in the superfluous length of the food canal and the overcrowding of the teeth. It is likely, however, that there will be constitutional changes, e.g., of prolonged youthfulness, a higher standard of healthfulness, and a greater resistance to disease. It is justifiable to look forward to great improvements in intelligence and in control. The potentialities of the human brain, as it is, are far from being utilized to the full, and new departures of promise are of continual occurrence. What is of great importance is that the new departures or variations which emerge and find children should be fostered, not nipped in the bud, by the social environment, education included. The evolutionary prospect for man is promising. But it is very important to realize that among plant and animals likewise, evolution is going on. The fountain of change, variability. On an ordinary big clock, we do not readily see that even the minute hand is moving, and if the clock struck only once in a hundred years, we can conceive of people arguing whether the hands did really move at all. So it often is with the changes that go on from generation to generation in living creatures. The flux is so slow, like the flowing of a glacier, that some people fail to be convinced of its reality. And it must, of course, be admitted that some kinds of living creatures, like the lamp-shell legula or the pearly nautilus, hardly change from age to age, whereas others, like some of the birds and butterflies, are always giving rise to something new. The evening primrose among plants and the fruit fly drosophilia among animals are well-known examples of organisms which are at present in a sporting or mutating mood. Certain dark varieties of moth, e.g. of the peppered moth, are taking the place of the paler type in some parts of England, and the same is true of some dark forms of sugar bird in the West Indian Islands. Very important is the piece of statistics worked out by Professor R. C. Punnett that, quote, if a population contains .001% of a new variety, and if that variety has even a 5% selection advantage over the original form, the latter will almost completely disappear in less than a hundred generations. This sort of thing has been going on all over the world for untold ages, and the face of animate nature has consequently changed. We are impressed by striking novelties that crop up, a clever dwarf, a musical genius, a calculating boy, a cock with a 10-foot tail, a wonder-horse with a mane reaching to the ground, a tailless cat, a white blackbird, a copper beach, a greater salondine with much cut-up leaves. But this sort of mutation is common, and smaller, less brusque variations are commoner still. They form the raw materials of possible evolution. We are actually standing before an apparently inexhaustible fountain of change. This is evolution going on. The Sporting Jellyfish It is of interest to consider a common animal like the Jellyfish Aurelia. It is admirably suited for a leisurely life in the open sea, where it swims about by contracting its saucer-shaped body, thus driving water out from its concavity. By means of millions of stinging cells on its four-filled lips and on its marginal tentacles, it is able to paralyze and lasso minute crustaceans and the like, which it then wafts into its mouth. It has a very eventful life history, for it has in its early youth to pass through a fixed stage, fastened to rock or seaweed. But it is a successful animal, well suited for its habitat, and practically cosmopolitan in its distribution. It is certainly an old established creature, yet it is very variable in color and in size, and even in internal structure. Very often it is the size of a saucer or a soup plate, but giants over two feet in diameter are well known. Much more important, however, than variation in color and size are the inborn changes in structure. Normally a Jellyfish has its parts in four or multiples of four. Thus it has four-filled lips, four tufts of digestive filaments in its stomach, and four brightly colored reproductive organs. It has eight sense organs around the margin of its disc, eight branched and eight unbranched radial canals running from the central stomach to a canal around the circumference. The point of giving these details is just this, that every now and then we find a Jellyfish with its parts in sixes, fives, or threes, and with a multitude of minor idiosyncrasies. Even in the well-established Jellyfish there is a fountain of change. 1. Evolution of Plants It is instructive to look at the various kinds of cabbages, such as cauliflower and Brussels sprouts, kale and curly greens, and remember that they are all scions of the not very promising wild cabbage found in our shores. And are not all the aristocrat apple trees of our orchards descended from the plebeian crab-apple of the roadside? We know far too little about the precise origin of our cultivated plants, but there was no doubt that after man got ahold of them he took advantage of their variability to establish race after race, say of rose and chrysanthemum, of potato and cereal. The evolution of cultivated plants is continuing before our eyes, and the creations of Mr. Luther Burbank, such as the Stoneless Plum and the Primus Berry, the spineless cactus in the Shasta Daisy, are merely striking instances of what is always going on. There is reason to believe that the domestic dog has risen three times from three distinct ancestors, a wolf, a jackal, and a coyote, so a multiple pedigree must be allowed for in the case of the dog, and the same is true in regard to some other domesticated animals. But the big fact is the great variety of breeds that man has been able to fix after he once got started with a domesticated type. There are over 200 well-marked breeds of domestic pigeons, and there was very strong evidence that all are descended from the wild rocked of, just as the numerous kinds of poultry are descended from the jungle fowl of some parts of India and the Meleis Islands. Even more familiar is the way in which man has, so to speak, unpacked the complex fur of the wild rabbit, and established all the numerous color varieties which we see among domestic rabbits. And apart from color varieties there are long-haired angoras, and quaint lop-eared forums, and many more besides. All this points to evolution going on. The Romance of the Wheat It is well known that Neolithic man grew wheat, and some authorities have put the date of the first wheat harvest at between 15,000 and 10,000 years ago. The ancient civilizations of Babylonia, Egypt, Crete, Greece, and Rome were largely based on wheat, and it is highly probable that the first great wheat fields were in the fertile land between the Tigris and the Euphrates. The oldest Egyptian tombs that contain wheat, which, by the way, never germinates after its millennia of rest, belong to the First Dynasty and are about 6,000 years old. But there must have been a long history of wheat before that. Now it is a very interesting fact that the almost certain ancestor of the cultivated wheat is at present living on the arid and rocky slopes of Mount Hermon. It is called Triticum Hormonus, and it is varying notably today, as it did long ago when it gave rise to the ember, which was cultivated in the Neolithic age, and is the ancestor of all our ordinary wheats. We must think of Neolithic man noticing the big seeds of this hermand grass, gathering some of its heads, breaking the brittle, spikelet-bearing axis in his fingers, knocking off the rough ons, or bruising the spikelets in his hands, till the glooms or chaff separated off and could be blown away, chewing a mouthful of the seeds, and resolving to so and so again. That was the beginning of a long story, in the course of which man took advantage of the numerous variations that cropped up in this sporting stock and established one successful race after another on his fields. Virgil refers, in the Georgics, to the gathering of the largest and fullest ears of wheat in order to get good seed for another sowing, but it was not till the first quarter of the nineteenth century that the great step was taken, by men like Patrick Sheriff of Hattington, of deliberately selecting individual ears of great excellence and segregating their progeny from mingling with mediocre stock. This is the method which has been followed with remarkable success in modern times. One of the factors that assisted the Allies in overcoming the food crisis in the darkest period of the war was the virtue of Marquis wheat, a very prolific, early ripening, hard red spring wheat with excellent milling and baking qualities. It is now the dominant spring wheat in Canada and the United States, and it has enormously increased the real wealth of the world in the last ten years, 1921. Now our point is simply that this Marquis wheat is a fine example of evolution going on. In 1917 upwards of 250 million bushels of this wheat were raised in North America, and in 1918 upwards of 300 million bushels. Yet the whole originated from a single grain planted in an experimental plot at Ottawa by Dr. Charles E. Saunders so recently as the spring of 1903. We must not dwell too long on this particular instance of evolution, though it has meant much to our race. We wish, however, following Professor Buller's Essays on Wheat, 1919, to explain the method by which this good seed was discovered. From one we may learn all. The parent of Marquis wheat on the male side was the mid-Europe red fife, a first class cereal. The parent on the female side was less promising, a rather nondescript, not pure red wheat called red calcutta, which was imported from India into Canada about 30 years ago. The father was part of a cargo that came from the Baltic to Glasgow, and was happily included in a sample sent on to David Fife in Ontario about 1842. From one kernel of this sample David Fife started his stock of red fife, which was crossed by Dr. Saunders with hard red calcutta. The result of this cross was a medley of types, nearly a hundred varieties altogether, and it was in scrutinizing these that Dr. Saunders hit upon Marquis. He worked steadily through the material, studying head after head of what resulted from sowing, and selecting out those that gave most promise. Each of the heads selected was propagated, most of the results were rejected. The elect were sifted again and yet again, and finally Marquis wheat emerged, rich in constructive possibilities, probably the most valuable food plant in the world. It is like a romance to read that the first crop of the wheat that was destined within a dozen years to overtax the mightiest elevators in the land was stored away in the winter of 1904-05 in a paper packet no larger than an envelope. Thus from the wild wheat of Mount Hermon there evolved one of the most important food plants of the world. This surely is evolution going on. 2. Changes in the animal life of a country Nothing gives us a more convincing impression of evolution and being than a succession of pictures of the animal life of a country in different ages. Dr. James Ritchie, a naturalist of distinction, has written a masterly book, The Influence of Man on Animal Life in Scotland, 1920, in which we get the succession of pictures. Within itself, he says, a fauna is in a constant state of uneasy restlessness, an assemblage of creatures which in its parts ebbs and flows as one local influence or another plays upon it. There are temporary and local changes, endless disturbances and readjustments of the balance of nature. One year there is a plague of field voles, perhaps next year, grouse disease is rife. In one place there is huge increase of starlings, in another place of rabbits. Here cockshafer are in the ascendant, and there the moles are spoiling the pasture. But while the parts fluctuate, the fauna as a whole follows a path of its own. As well as internal tides, which swing to and fro about an average level, there is a drift which carries the fauna bodily along an irretraceable course. This is partly due to considerable changes of climate, for climate calls the tune to which living creatures dance. But it is also due to new departures among the animals themselves. We need not go back to the extinct animals and lost faunas of past ages, for Britain has plenty of relics of these, which illustrate the reality of the faunal drift. But it may be very useful, in illustration of evolution in being, to notice what has happened in Scotland since the end of the Great Ice Age. Some 9000 years ago or more, certain long-headed, square jawed, short-limbed, but agile hunters and fishermen, whom we call Neolithic men, established themselves in Scotland. What was the state of the country then? It was a country of swamps, low forests of birch, alder, and willow, fertile meadows, and snow-capped mountains. Its estuaries penetrated further inland than they do now, and the sea stood at the level of the 50-foot beach. On its plains and in its forests roamed many creatures which are strange to the fauna of today, the elk and the reindeer, wild cattle, the wild boar, and perhaps wild horses, a fauna of large animals which paid toll to the European lynx, the brown bear, and the wolf. In all likelihood the marshes resounded to the boom of the bittern and the plains to the breeding-calls of the crane and the Great Bustard. Such is Dr. Richie's initial picture. Now what happened in this kingdom of Caledonia which Neolithic men had found? He began to introduce domesticated animals, and that meant a thinning of the ranks of predacious creatures. Safety first was the dangerous motto in obedience to which man exterminated the lynx, the brown bear, and the wolf. Other creatures, such as the great awk, were destroyed for food, and others like the martin for their furs. Small pests were destroyed to protect the beginnings of agriculture. Larger animals like the boar were hunted out of existence. Others, like the pearl-bearing river mussels, yielded to subtler demands. No doubt there was protection also, protection for sport, for utility, for aesthetic reasons, and because of humane sentiments. Even wholesome superstitions have safeguarded the robin-red breast and the wren. There were introductions too, the rabbit for utility, the pheasant for sport, and the peacock for amenity. And every introduction, every protection, every killing out had its far-reaching consequences. But if we are to picture the evolution going on, we must think also of man's indirect interference with animal life. He destroyed the forests, he cultivated the wild, he made bridges, he allowed aliens, like rats and cockroaches, to get in unawares. Of course he often did good, as when he drained swamps and got rid of the mosquitoes which once made malaria rife in Scotland. What has been the net result? Not, as one might think for a moment, a reduction in the number of different kinds of animals. Fourteen or so species of birds and beasts have been banished from Scotland since man interfered. But as far as numbers go, they have been more than replaced by deliberate introductions like fallow deer, rabbit, squirrel, and pheasant, and by accidental introductions like rats and cockroaches. But the change is rather in quality than in quantity. The smaller have taken the place of the larger, rather paltry pygmies of noble giants. Thus we get a vivid idea that evolution, especially when man interferes, is not necessarily progressive. That depends on the nature of the sieves with which the living materials are sifted. As Dr. Richie Well says, the standard of the wild fauna as regards size has fallen and is falling, and it is not in size only that there is loss, there is a deterioration of quality. Quote, for how can the increase of rabbits and sparrows and earthworms and caterpillars, and the additions of millions of rats and cockroaches and crickets and bugs, ever take the place of those fine creatures round the memories of which the glamour of Scotland's past still plays? The reindeer and the elk, the wolf, the brown bear, the lynx and the beaver, the bustered, the crane, the bumbling bittern, and many another lost or disappearing. Thus we see again that evolution is going on. 3. The Adventurers All through the millions of years during which animals have tenanted the earth and the waters under the earth, there has been a search for new kingdoms to conquer, for new corners in which to make a home, and this still goes on. It has been and is one of the methods of evolution to fill every niche of opportunity. There is a spider that lives inside a pitcher plant, catching some of the inquisitive insects which slipped down the treacherous internal surface of the trap. There is another that makes its home in crevices, among the rocks on the shore of the Mediterranean, or even in empty tubular shells, keeping the water out, more or less successfully, by spinning threads of silk across the entrance to its retreat. The beautiful brine shrimp, Artemis alina, that used to occur in British Souturns, has found a home in the dense waters of the Great Salt Lake of Utah. Several kinds of earthworms have been found up trees, and there is a fish, Arches, that climbs on the stones of steep mountain torrents of the Andes. The intrepid explorers of the Scotia voyage found quite a number of arctic turns spending our winter within the summer of the Antarctic Circle, which means girdling the globe from pole to pole. And every now and then there are incursions of rare birds, like Pallas's sand-grouse, into Britain, just as if they were prospecting in search of a promised land. Twice or thrice the distinctively North American kill-deer plover has been found in Britain, having somehow or other got across the Atlantic. We miss part of the meaning of evolution if we do not catch this note of insurgence and adventure, which some animal or other never ceases to sound, though many establish themselves in a security not easily disturbed, and though a small minority give up the struggle against the stream and are content to acquiesce as parasites or rottenness eaters in a drifting life of ease. More important than very peculiar cases is the broad fact that over and over again, in different groups of animals, there have been attempts to master different kinds of haunts, such as the underground world, the trees, the fresh waters, and the air. There are burrowing amphibians, burrowing reptiles, burrowing birds, and burrowing mammals. There are tree toads, tree snakes, tree lizards, tree kangaroos, tree sloths, tree shrews, tree mice, tree porcupines, and so on. Enough of a list to show, without mentioning birds, how many different kinds of animals have entered upon an arboreal apprenticeship, an apprenticeship often with far-reaching consequences. What the freeing of the hand from being an organ of terrestrial support has meant in the evolution of monkeys is a question that gives a spur to our imagination. The Case of the Robber Crab On some of the coral islands of the Indian and Pacific Oceans there lives a land crab, Burgus, which has learned to breathe on land. It breathes dry air by means of curious blood-containing tufts in the upper part of its gill cavity, and it also has rudimentary gills. It is often about a foot long, and it has very heavy great claws, especially on the left-hand side. With this great claw it hammers on the eye-hole of a coconut, from which it is torn off the fibrous husk. It hammers until a hole is made by which it can get at the pulp. Part of the shell is sometimes used as a protection for the soft abdomen. For the robber crab, as it is called, is an offshoot from the hermit crab stock. Every year this quaint explorer, which may go far up the hills and climb the cocoa palms, has to go back to the sea to spawn. The young ones are hatched in the same state as in our common shore-crab. That is to say, they are free-swimming larvae which pass through an open-water period before they settle down on the shore, and eventually creep up onto dry land. Just as open-water turtles lay their eggs on sandy shores, going back to their old terrestrial haunt, so the robber crab, which has almost conquered the dry land, has to return to the seashore to breed. There is a peculiar interest in the association of the robber crab with the cocoa palm, for that tree is not a native of these coral islands, but has been introduced, perhaps from Mexico, by the Polynesian mariners before the discovery of America by Columbus. So the learning to deal with coconuts is a recent achievement, and we are face-to-face with a very good example of evolution going on. The Story of the Salmon In late autumn or in winter, the salmon spawn in the rivers. The female makes a shallow trough in the gravel by moving her tail from side to side, and therein lays many eggs. The male, who is in attendance, fertilizes these with the milk, and then the female covers them deeply with gravel. This process is repeated over and over again for a week or more till all the eggs are shed. For three to four months the eggs develop, and eventually there emerge the larvae, or alavons, which lurk among the pebbles. They cannot swim much, for they are encumbered by a big legacy of yolk. In a few weeks, perhaps eight, the protruding bag of yolk has disappeared, and the fry, about an inch long, begin to move about more actively and defend for themselves. By the end of the year they have grown to be rather trout-like par about four inches long. In two years these are double that length. Usually in the second year, but it may be earlier or later, the par becomes silvery smolts, which go out to sea, usually about the month of May. They feed on young herring and the like, and grow large and strong. When they are about three-and-a-half years old, they come up the rivers as grills, and may spawn. Or they may pass through the whole grills stage in the sea, and come up the rivers with all the characters of the full-grown fish. In many cases the salmon spawn only once. In some, they are called kelts after spawning, are so much exhausted by starting a new generation that they die or fall victim to otters and other enemies. In the case of the salmon of the North Pacific, in the genus Oncorhynchus, Salmo, all the individuals die after spawning, none being able to return to the sea. It must be remembered that full-grown salmon do not as a rule feed in fresh waters, though they may be unable to resist snapping at the angler's strange creations. A very interesting fact is that the salmon keeps as it were a diary of its movements, which vary a great deal in different rivers. This diary is written in the scales, and a careful reading of the concentric lines on the scales shows the age of the fish and when it went out to sea, and whether it is spawned or not, and more besides. Interpretation of the salmon's story When an animal frequents two different haunts, in one of which it breeds, it is very often safe to say that the breeding place represents the original home. The flounder is quite comfortable far up the rivers, but it has to go to the shore waters to spawn, and there is no doubt that the flounder is a marine fish which has recently learned to colonize the fresh waters. Its relatives, like place and soul, are strictly marine, but it is impossible to make a dogma of the rule that the breeding place corresponds to the original home. Thus some kinds of bass, which belong to the marine family of sea perches, live in the sea, or in estuaries, while too have become permanent residents in fresh water. Or again the members of the herring family are very distinctively marine, but the shad, which belong to this family, spawn in rivers, and may spend their lives there. So there are two different ways of interpreting the life history of the salmon. Some authorities regard the salmon as a marine fish, which is establishing itself in fresh water. But others read the story the other way, and regard the salmon as a member of the freshwater race that is taken to the sea for feeding purposes. In regard to trout, we know that the ranks of those in rivers and lakes are continually being reinforced by migrants from the sea, and that some trout go down to the sea while others remain in the freshwater. We know also in regard to a related fish, the char, that while the great majority of kinds are now permanent residents in cold and deep isolated northern lakes, there are arctic forms, which live in the sea, but enter the rivers to spawn. These facts favor the view that the salmon was originally a marine fish. But there are arguments on both sides, and for our present purpose the important fact is that the salmon is conquering two haunts. Its evolution is going on. The Romance of the Eel Early in summer, at dates varying with the distance of the rivers from the open Atlantic, crowds of young eels or elvers come upstream. Sometimes the procession of eel fare includes thousands of individuals, each about the length of our first finger, and as thick as a stout knitting needle. They obey an inborn impulse to swim against the stream, seeking automatically to have both sides of their bodies equally stimulated by the current. So they go straight ahead. The obligation works only during the day, for when the sun goes down behind the hills, the elvers snuggle under stones, or beneath the bank, and rest till dawn. In the course of time they reach the quiet upper reaches of the river, or go up rivulets and drain pipes to the isolated ponds. Their impulse to go on must be very imperious, for they may wriggle up the wet moss by the side of a waterfall, or even make a short excursion in a damp meadow. In the quiet flowing stretches of the river, or in the ponds, they feed and grow for years and years. They account for a good many young fishes. Eventually, after five or six years in the case of the males, six to eight years in the case of the females, the well-grown fishes, perhaps a foot and a half to two feet long, are seized by a novel restlessness. They are beginning to be mature. They put on a silvery jacket, and become large of eye, and they return to the sea. In getting away from the pond, it may be necessary to wriggle through the damp meadow-grass before reaching the river. They travel by night, and rather excitedly. The Arctic Ocean is too cold for them, and the North Sea too shallow. They must go far out to sea, to where the old margin of the once larger continent of Europe slopes down to the Great Abysses, from the Hebrides southwards. Eels seem to spawn in the deep dark water, but the just liberated eggs have not yet been found. The young fry rises to near the surface, and becomes a knife-blade-like larva, transparent all but its eye. It lives for many months in this state, growing to be about three inches long, rising and sinking in the water, and swimming gently. These open-sea young eels are known as Leptisephalae, a name given to them before their real nature was proved. They gradually become shorter, and the shape changes from knife-blade-like to cylindrical. During this change they fast, and the weight of their delicate body decreases. They turn into glass eels, about two and a half inches long, like a knitting needle in girth. They begin to move towards the distant shores and rivers, and they may be a year and a half old before they reach their destination and go upstream as elvers. Those that ascend the rivers of the eastern Baltic must have journeyed three thousand miles. It is certain that no eel ever matures or spawns in fresh water. It is practically certain that all the young eels ascending the rivers of North Europe have come in from the Atlantic, some of them perhaps from the Azores, or further out still. It is interesting to inquire how the young eels circumvent the falls of the Rhine and get into Lake Constance, or how their kindred on the other side of the Atlantic overcome the obstacle of Niagara. But it is more important to lay emphasis on the variety of habitats which this fish is trying. The deep waters, the open sea, the shore, the river, the pond, and even, it may be, a little taste of solid earth. It seems highly probable that the common eel is a deep water marine fish which has learned to colonize the fresh waters. It has been adventurous and it has succeeded. The only shadow on the story of achievement is that there seems to be no return from the spawning. There is little doubt that death is the nemesis of their reproduction. In any case, no adult eel ever comes back from the deep sea. We are reminded of Goethe's hard saying. Death is nature's expert advice to get plenty of life. 4. Forming New Habits There is a well-known mudfish of Australia, Neoceratidus by name, which has turned its swim bladder into a lung and comes to the surface to spout. It expels vitiated air with considerable force and takes fresh gulps. At the same time, like an ordinary fish, it has gills which allow the usual interchange of gases between the blood and the water. Now this Australian mudfish, or double breather, Dipnoen, which may be a long way over a yard in length, is a direct and little-changed descendant of an ancient extinct fish, Ceratidus, which lived in Mesozoic times, as far back as the Jurassic, which probably means over five millions of years ago. The Queensland mudfish is an antiquity, and there has not been much change in its lineage for millions of years. We might take it as an illustration of the inertia of evolution. And yet, though its structure has changed but little, the fish probably illustrates evolution in process, for it is a fish that is learning to breathe dry air. It cannot leave the water, but it can live comfortably in pools which are foul with decomposing animal and vegetable matter. In partially dried up and foul waterholes full of dead fishes or various kinds, Neoceratidus has been found vigorous and lively. Unless we take the view, which is possible, that the swim bladder of fishes was originally a lung, the mudfishes are learning to breathe dry air. They illustrate evolution agoing. The herring-goal is by nature a fish-eater, but of recent years, in some parts of Britain, it has been becoming in the summer months more and more of a vegetarian, scooping out the turnips, devouring potatoes, settling on the sheaves in the harvest field, and gorging itself with grain. Similar experiments, usually less striking, are known in many birds, but the most signal illustration is that of the Kia or Nestor parrot of New Zealand, which has taken to lighting on the loins of the sheep, tearing away the fleece, cutting at the skin, and gouging out fat. Now the parrot belongs to a vegetarian or frugivorous stock, and this change of diet in the relatively short time since sheep ranches were established in New Zealand, is very striking. Here, since we know the dates, we may speak of evolution going on under our eyes. It must be remembered that variations in habit may give an animal a new opportunity to test variations in structure, which arise mysteriously from within, as expressions of germinal changefulness, rather than as imprints from without. For of the transmissibility of the latter, there is little secure evidence. Experiments in locomotion It is very interesting to think of the numerous types of locomotion which animals have discovered, pulling and punting, sculling and rowing, and of the changes that are rung on these four main methods. How striking is the case of the frilled lizard, Clemitosaurus of Australia, which at the present time is, as it were, experimenting in bipedal progression, always a rather eventful thing to do. It gets up on its hind legs and runs totteringly for a few feet, just like a baby learning to walk. How beautiful is the adventure which has led our dipper or water-oozel, a bird allied to the rins, to try walking and flying underwater. How admirable is the vole-planing of numerous parachutists, flying fish, flying frog, flying dragon, flying phalanger, flying squirrel, and more besides, which take great leaps through the air. For are these not the splendid failures that might have succeeded in starting new modes of flight? Most daring of all, perhaps, are the aerial journeys undertaken by many small spiders. On a breezy morning, especially in the autumn, they mount on gate-posts and palinks and herbage, and, standing with their head to the wind, pay out three or four long threads of silk. When the wind tugs at these threads, the spinners let go, and are born, usually back downwards, on the wings of the wind from one parish to another. It is said that if the wind falls, they can unfurl more sail, or furl if it rises. In any case, these wingless creatures make aerial journeys. When tens of thousands of the used threads sink to earth, there is a shower of gossamer. On his beagle voyage, Darwin observed that vast numbers of small gossamer spiders were born onto the ship when it was sixty miles distant from the land. New Devices It is impossible, we must admit, to fix dates except in a few cases, relatively recent. But there is a smack of modernity in some striking devices which we can observe in operation today. Thus no one will dispute the statement that spiders are thoroughly terrestrial animals breathing dry air, but we have the fact of the water spider conquering the underwater world. There are a few spiders about the seashore, and a few that can survive douching with fresh water. But the particular case of the true water spider, Argyronitanatans, stands by itself because the creature, as regards the female at least, has conquered the subaquatic environment. A flat-ish web is woven, somehow, underneath the water, and pegged down by threads of silk. Along a special vertical line, the mother spider ascends to the surface and descends again, having entangled air in the hairs of her body. She brushes off this air underneath her web, which is thereby buoyed up in a sort of dome. She does this over and over again, never getting wet all the time, until the domed web has become like a diving bell, full of dry air. In this eloquent anticipation of man's rational device, this creature, far from being endowed with reason, lays her eggs and looks after her young. The general significance of the facts is that when competition is keen, a new area of exploitation is a promised land. Thus spiders have spread over all the earth except the polar areas. But here is a spider with some spirit of adventure, which has endeavored, instead of trekking, to find a new corner near at home. It has tackled a problem surely difficult for a terrestrial animal, the problem of living in great part under water, and it has solved it in a manner at once effective and beautiful. In conclusion. We have given but a few representative illustrations of a great theme. When we consider the changefulness of living creatures, the transformations of cultivated plants and domesticated animals, the gradual alterations in the fauna of a country, the search after new haunts, the forming of new habits, and the discovery of many inventions, are we not convinced that evolution is going on? And why should it stop? End of section 10.