The Antiquity of Man

The law of continuity here spoken of, as not being violated by occasional exceptions, or by leaps from one creature to another, is not the law of variation and natural selection above explained (Chapter 21), but that unity of plan supposed to exist in the Divine Mind, whether realised or not materially and in the visible creation, of which the "links do not pass by an easy transition" the one into the other, at least as beheld by us.

Dr. Asa Gray, an eminent American botanist, to whom we are indebted for a philosophical essay of great merit on the "Origin of Species by Variation and Natural Selection," has well observed, when speaking of the axiom of Leibnitz, "Natura non agit saltatim," that nature secures her ends and makes her distinctions, on the whole, manifest and real, but without any important breaks or long leaps. "We need not wonder that gradations between species and varieties should occur, or that genera and other groups should not be absolutely limited, though they are represented to be so in our systems. The classifications of the naturalist define abruptly where nature more or less blends. Our systems are nothing if not definite."

The same writer reminds us that "plants and animals are so different, that the difficulty of the ordinary observer would be to find points of comparison, whereas, with the naturalist, it is all the other way. All the broad differences vanish one by one as we approach the lower confines of the animal and vegetable kingdoms, and no absolute distinction whatever is now known between them."*

The author of an elaborate review of Darwin's "Origin of Species," himself an accomplished geologist, declares that if we embrace the doctrine of the continuous variation of all organic forms from the lowest to the highest, including Man as the last link in the chain of being, there must have been a transition from the instinct of the brute to the noble mind of Man; and in that case, "where," he asks, "are the missing links, and at what point of his progressive improvement did Man acquire the spiritual part of his being, and become endowed with the awful attribute of immortality?"*

Before we raise objections of this kind to a scientific hypothesis, it would be well to pause and inquire whether there are no analogous enigmas in the constitution of the world around us, some of which present even greater difficulties than that here stated. When we contemplate, for example, the many hundred millions of human beings who now people the earth, we behold thousands who are doomed to helpless imbecility, and we may trace an insensible gradation between them and the half-witted, and from these again to individuals of perfect understanding, so that tens of thousands must have existed in the course of ages, who in their moral and intellectual condition, have exhibited a passage from the irrational to the rational, or from the irresponsible to the responsible. Moreover we may infer from the returns of the Registrar General of births and deaths in Great Britain, and from Quetelet's statistics of Belgium, that one-fourth of the human race die in early infancy, nearly one-tenth before they are a month old; so that we may safely affirm that millions perish on the earth in every century, in the first few hours of their existence. To assign to such individuals their appropriate psychological place in the creation is one of the unprofitable themes on which theologians and metaphysicians have expended much ingenious speculation.

The philosopher, without ignoring these difficulties, does not allow them to disturb his conviction that "whatever is, is right," nor do they check his hopes and aspirations in regard to the high destiny of his species; but he also feels that it is not for one who is so often confounded by the painful realities of the present, to test the probability of theories respecting the past, by their agreement or want of agreement with some ideal of a perfect universe which those who are opposed to opinions may have pictured to themselves.

We may also demur to the assumption that the hypothesis of variation and natural selection obliges us to assume that there was an absolutely insensible passage from the highest intelligence of the inferior animals to the improvable reason of Man. The birth of an individual of transcendent genius, of parents who have never displayed any intellectual capacity above the average standard of their age or race, is a phenomenon not to be lost sight of, when we are conjecturing whether the successive steps in advance by which a progressive scheme has been developed may not admit of occasional strides, constituting breaks in an otherwise continuous series of psychical changes.

The inventors of useful arts, the poets and prophets of the early stages of a nation's growth, the promulgators of new systems of religion, ethics, and philosophy, or of new codes of laws, have often been looked upon as messengers from Heaven, and after their death have had divine honours paid to them, while fabulous tales have been told of the prodigies which accompanied their birth. Nor can we wonder that such notions have prevailed when we consider what important revolutions in the moral and intellectual world such leading spirits have brought about; and when we reflect that mental as well as physical attributes are transmissible by inheritance, so that we may possibly discern in such leaps the origin of the superiority of certain races of mankind. In our own time the occasional appearance of such extraordinary mental powers may be attributed to atavism; but there must have been a beginning to the series of such rare and anomalous events. If, in conformity with the theory of progression, we believe mankind to have risen slowly from a rude and humble starting point, such leaps may have successively introduced not only higher and higher forms and grades of intellect, but at a much remoter period may have cleared at one bound the space which separated the highest stage of the unprogressive intelligence of the inferior animals from the first and lowest form of improvable reason manifested by Man.

To say that such leaps constitute no interruption to the ordinary course of nature is more than we are warranted in affirming. In the case of the occasional birth of an individual of superior genius there is certainly no break in the regular genealogical succession; and when all the mists of mythological fiction are dispelled by historical criticism, when it is acknowledged that the earth did not tremble at the nativity of the gifted infant and that the face of heaven was not full of fiery shapes, still a mighty mystery remains unexplained, and it is the ORDER of the phenomena, and not their CAUSE, which we are able to refer to the usual course of nature.

Dr. Asa Gray, in the excellent essay already cited, has pointed out that there is no tendency in the doctrine of Variation and Natural Selection to weaken the foundations of Natural Theology, for, consistently with the derivative hypothesis of species, we may hold any of the popular views respecting the manner in which the changes of the natural world are brought about. We may imagine "that events and operations in general go on in virtue simply of forces communicated at the first, and without any subsequent interference, or we may hold that now and then, and only now and then, there is a direct interposition of the Deity; or, lastly, we may suppose that all the changes are carried on by the immediate orderly and constant, however infinitely diversified, action of the intelligent, efficient Cause." They who maintain that the origin of an individual, as well as the origin of a species or a genus, can be explained only by the direct action of the creative cause, may retain their favourite theory compatibly with the doctrine of transmutation.

Professor Agassiz, having observed that, "while human thought is consecutive, divine thought is simultaneous," Dr. Asa Gray has replied that, "if divine thought is simultaneous, we have no right to affirm the same of divine action."

The whole course of nature may be the material embodiment of a preconcerted arrangement; and if the succession of events be explained by transmutation, the perpetual adaptation of the organic world to new conditions leaves the argument in favour of design, and therefore of a designer, as valid as ever; "for to do any work by an instrument must require, and therefore presuppose, the exertion rather of more than of less power, than to do it directly."*

As to the charge of materialism brought against all forms of the development theory, Dr. Gray has done well to remind us that "of the two great minds of the seventeenth century, Newton and Leibnitz, both profoundly religious as well as philosophical, one produced the theory of gravitation, the other objected to that theory, that it was subversive of natural religion."*

It may be said that, so far from having a materialistic tendency, the supposed introduction into the earth at successive geological periods of life—sensation—instinct—the intelligence of the higher mammalia bordering on reason—and lastly the improvable reason of Man himself, presents us with a picture of the ever-increasing dominion of mind over matter.

NOTES.

1 (return)
[ The classification of the strata above the Chalk, as at present employed by the majority of British geologists, is merely a slight modification of that proposed by Lyell in 1833. The subdivisions generally recognised are as follows (Lake and Rastall, "Textbook of Geology," London, 1910, page 438):—

This differs chiefly from Lyell's classification in the introduction of the term Oligocene for the upper part of the original Eocene, which was somewhat unwieldy. In the earlier editions of the "Antiquity of Man" and of the "Principles of Geology," the strata here classed as Pleistocene were designated as Post-pliocene. The term "diluvium," now obsolete in Britain but still lingering on the Continent, is equivalent to Pleistocene. This subdivision is still sometimes separated from the Tertiary, as the Quaternary epoch. This, however, is unnecessary and indeed objectionable, as attributing too great importance to relatively insignificant deposits. There is no definite break, either stratigraphical or palaeontological, at the top of the Pliocene, and it is most natural to regard the Tertiary epoch as still in progress. Equally unnecessary is the separation of the post-glacial deposits as "Recent," a distinction which still prevails in many quarters, apparently with the sole object of adding another name to an already over-burdened list.]

2 (return)
[ The table of strata here printed is not that given by Lyell in the later editions of the "Antiquity of Man." This would have required so much explanation in the light of modern work that it was thought better to abolish it altogether and to substitute an entirely new table, which is to some extent a compromise between the numerous classifications now in vogue. In this form it is only strictly applicable to the British Isles, though the divisions adopted in other countries are generally similar, and in many cases identical.]

3 (return)
[ A similar succession of forest-beds, five in number, has been observed in the peat of the Fenland, near Ely. Each bed consists for the most part of a single species of tree, and a definite succession of oak, yew, Scotch fir, alder, and willow has been made out. The forest beds are supposed to indicate temporarily drier conditions, due either to changes of climate or to slight uplift of the land, the growth of peat being renewed during periods of damp climate or of depression of the land. (See Clement Reid, "Submerged Forests," Cambridge, 1913.)]

4 (return)
[ Since the "Stone Age," in the sense in which the term is here employed, obviously occupied an enormous lapse of time and embraced very different stages of culture, it has been found convenient to subdivide it into two primary subdivisions. For these Lord Avebury proposed in 1865 the terms Palaeolithic and Neolithic. (" Prehistoric Times," London, 1865, page 60.) The first comprises the ages during which man fabricated flint implements solely by chipping, whereas the implements of Neolithic Age are polished by rubbing. But there is another and more fundamental distinction. Palaeolithic man was exclusively a hunter, and consequently nomadic in his habits; Neolithic man possessed domesticated animals and cultivated crops. A pastoral and agricultural life implies a settled abode, and these are found, for example, in the lake-villages of Switzerland. The "kitchen-middens" of Denmark also indicate long continuance in one place, in this instance the seashore.]

5 (return)
[ The famous case of the so-called Temple of Serapis at Pozzuoli, has given rise to a considerable literature. The subject is discussed by Suess at length ("Des Antlitz der Erde," Vienna, 1888, volume 2 page 463, or English translation, "The Face of the Earth," Oxford, 1904). This author shows that the whole region is highly volcanic, and consequently very liable to disturbance, much relative movement of land and sea having occurred within historic times. Hence the facts here observed cannot be taken as evidence for any general upward or downward movement of wide-spread or universal extent.]

6 (return)
[ Darwin, "Voyage of the Beagle," chapter 14, and a much fuller account in the same author's "Geological Observations on the Volcanic Islands and Parts of South America Visited during the Voyage of H.M.S. Beagle," chapter 9.]

7 (return)
[ For a full discussion of the evidence for and against continental elevation and subsidence in general, and as affecting the British Isles and Scandinavia in particular, see Sir A. Geikie's Presidential Address to the Geological Society for 1904 (" Proceedings of the Geological Society"' volume 60, 1904, pages 80 to 104.). Here it is shown that the oldest raised beaches of Scotland are pre-glacial, and the same also holds for the south of Ireland.]

8 (return)
[ The argument here employed is fallacious, since the mere existence of a distinct beach implies a pause in the movement and a long continuance at one level. It is impossible to form any estimate of the lapse of time necessary for the building up of a beach-terrace. We can only, in some cases, obtain a measure of the time that elapsed between the formation of two successive beaches, as in this instance.]

9 (return)
[ The "strand lines," or raised beaches of Norway, have given rise to much discussion, of which a summary will be found in the address cited in Note 7.]

10 (return)
[ A considerable number of skulls and skeletons of the Neanderthal type have now been found in different parts of Southern Europe, extending from Belgium to Gibraltar and Croatia, and it is now known that this type of skull is associated with flint implements of Mousterian Age. (See Note 12.)]

11 (return)
[ The most important discovery of recent years in this connection is that made in Sussex by Mr. C. Dawson and Dr. A. Smith Woodward; this find is described in great detail in the "Quarterly Journal of the Geological Society," volume 69, 1913, pages 117 to 151. At a height of about 80 feet above the present level of the River Ouse, at Piltdown, near Uckfield, is a gravel, containing many brown flints of peculiar character, some of which are implements of Chellean or earlier type, associated with some remains of Pleistocene animals and a few of older date, derived from Pliocene deposits. Embedded in this gravel were found fragments of a human skull and lower jaw of very remarkable type, showing in some respects distinctly simian characters, while in other respects it is less ape-like than the Mousterian skulls of Neanderthal and other localities. For this form the name of Eoanthropus has been proposed, thus constituting a new genus of the Hominidae.]

12 (return)
[ It will be well at this point to give a brief summary of the modern classification of the Palaeolithic implement-bearing deposits of Europe. From the labours of many geologists and prehistoric archaeologists, especially in France, a definite succession of types of implement has been established, and in some cases it has been found possible to correlate these with actual human remains and with certain well-marked events in the physical history of Pleistocene times, especially with the advance and retreat of ice-sheets. The present state of our knowledge is admirably summarised by Professor Sollas ("Ancient Hunters," London, 1911), and from that work the following note is condensed.

The stages of Palaeolithic culture now recognised are as follows:—

Below the Mesvinian comes the nebulous region of "eoliths," which are not yet definitely proved to be of human workmanship. The Neanderthal skull belongs to the Mousterian stage, but the oldest known definitely human remain, the jaw from the Mauer sands near Heidelberg, may be older than any of these, indeed by some it is assigned to the first interglacial period of Penck and Bruckner (see Note 32). For figures of the types of implement characterising each period, see "Guide to the Antiquities of the Stone Age in the Department of British and Medieval Antiquities," British Museum, 2nd edition, London, 1911, pages 1 to 74. This publication gives an admirable summary of recent knowledge on this subject. For an excellent and critical summary of the latest researches on Palaeolithic man up till the end of the Aurignacian period, see Duckworth, "Prehistoric Man," Cambridge, 1912. See also note 44.]

13 (return)
[ Sir John Evans, K.C.B. (1823-1908), was one of the foremost authorities on prehistoric archaeology and a prolific writer on the subject. His best known work is "The Ancient Stone Implements, Weapons, and Ornaments of Great Britain," 2nd edition, 1897.]

14 (return)
[ By the expression "Celtic weapons of the stone period" is presumably meant Neolithic implements, with polished surfaces.]

15 (return)
[ It has recently been shown that the growth of peat is a very slow process, and at the present time it is in many places either at a standstill or even in a state of retrogression. In the peat-mosses of Scotland, Lewis has traced nine successive layers, marked by different floras. The lowest of these and another at a higher level are distinctly of an arctic character, the intermediate forest beds, on the other hand, indicate periods of milder climate, when the limit of the growth of trees was at a higher level in Scotland than is now the case. From these facts it is certain that the peat-mosses of Scotland and northern England date back at least as far as the later stages of the glacial period, and indicate at least one mild interglacial episode, when the climate was somewhat warmer than it now is. (See Lewis, "Science Progress," volume 2, 1907, page 307.) Hence the statements of the French workmen, here quoted, do not possess much significance.]

16 (return)
[ Cyrena fluminalis is very abundant in the gravels of an old terrace of the River Cam, at Barnwell, in the suburbs of Cambridge, and also in glacial gravels at Kelsey Hill in Holderness. It is a very remarkable fact that this shell, now an inhabitant of warm regions, should be so abundant in these Pleistocene deposits, in close association with glacial accumulations.]

17 (return)
[ The implement-bearing deposits of Hoxne, in Suffolk, were investigated with great care by a committee of the British Association, and the results were published in a special and detailed report ("The Relation of Palaeolithic Man to the Glacial Epoch," "Report of the British Association," Liverpool, 1896, pages 400 to 415). The deposit consists of a series of lacustrine or fluviatile strata with plant remains, some being arctic in character, resting on Chalky Boulder Clay, and this again on sand. The Palaeolithic deposits are all clearly later than the latest boulder-clay of East Anglia, and between their formation and that of the glacial deposits at least two important climatic changes took place, indicating a very considerable lapse of time.

Mention may conveniently be made here of the supposed discovery of the remains of pre-glacial man at Ipswich, which appears to be founded on errors of observation. The boulder-clay above the interment is, according to the best authorities, merely a landslip or flow.]

18 (return)
[ It has been suggested with a considerable degree of probability, that in Auvergne volcanic eruptions persisted even into historic times. The subject is obscure, depending on the interpretation of difficult passages in two Latin chronicles of the fifth century. The most obvious meaning of both passages would certainly appear to be the occurrence of volcanic eruptions and earthquakes, but attempts have been made to explain them as referring to some artificial conflagration, possibly the burning of a town by an invader. (See Bonney, "Volcanoes," 3rd edition, London, 1913, page 129.)]

19 (return)
[ In the early days of glacial geology in Britain, it was commonly accepted that the phenomena could be most satisfactorily explained on the hypothesis of a general submergence of the northern parts of the country to a depth of many hundreds of feet, and this in spite of the original comparison by Agassiz of the glacial deposits of Britain to those of the Alps. In later times, however, a school of geologists arose who attributed the glaciation of Britain to land-ice of the Continental or Greenland type. Of late years this school has been dominant in British geology, with a few notable exceptions, of whom the most important is Professor Bonney. The difficulties presented by both theories are almost equally great, and at the present time, in spite of the vehemence of the supporters of the land-ice theory, it is impossible to hold any dogmatic views on the subject. Against the doctrine of submergence is the absence of glacial deposits in places where they would naturally be expected to occur if the whole of the British Isles north of the Thames and Bristol Channel had been covered by the sea, together with the very general absence of sea-shells in the deposits. The objections to the land-ice hypothesis are largely of a mechanical nature. If we take into account the lateral extent and the thickness that can be assigned to the ice-sheet, we are at once confronted by very considerable difficulties as to the sufficiency of the driving-power behind the ice. Another great difficulty is the shallowness of the North Sea, in which a comparatively thin mass of ice would run aground at almost any point. It has been calculated that the maximum slope of the surface of the ice from Norway to the English coast could not exceed half a degree, and it is therefore difficult to see what force could compel it to move forward at all, much less to climb steep slopes in the way postulated by the extremists of this school.]

20 (return)
[ The most complete account of the geology of the Norfolk coast is contained in "The Geology of Cromer," by Clement Reid ("Memoir of the Geological Survey"). (See also Harmer, "The Pleistocene Period in the Eastern Counties of England," "Geology in the Field, the Jubilee Volume of the Geologists Association," 1909, chapter 4.). Above the Norwich Crag several more subdivisions are now recognised, and the complete succession of the Pliocene and Pleistocene strata of East Anglia may be summarised as follows:—

21 (return)
[ It is now generally agreed that the tree-stumps in the Cromer Forest bed are not in the position of growth. Many of them are upside down or lying on their sides, and they were probably floated into their present position by the waters of a river flowing to the north. This river was a tributary of the Rhine which then flowed for several hundred miles over a plain now forming the bed of the North Sea, collecting all the drainage of eastern England, and debouching into the North Atlantic somewhere to the south of the Faroe Isles. (See Harmer, "The Pleistocene Period in the Eastern Counties of England," "Geological Association Jubilee Volume," London, 1909, pages 103 to 123.)]

22 (return)
[ Of late years an enormous number of characteristic rocks from Norway and Sweden have been recognised in the drifts of Eastern England, as far south as Essex and Middlesex. One of the most easily identifiable types is the well-known Rhombporphyry of the Christiania Fjord, a rock which occurs nowhere else in the world, and is quite unmistakable in appearance. Along with it are many of the distinctive soda-syenites found in the same district, the granites of southern Sweden, and many others. The literature of the subject is very large, but many details may be found in the annual reports of the British Association for the last twenty years.]

From a study of these erratics it has been found possible to draw important conclusions as to the direction and sequence of the ice streams which flowed over these regions during the different stages of the glacial period.]

23 (return)
[ During his first crossing of Greenland from east to west, Nansen attained a height of 9000 feet on a vast expanse of frozen snow, and it is believed that towards the north the surface of this great snow-plateau rises to even greater elevations. The surface of the snow is perfectly clean and free from moraine-material. No rock in situ has been seen in the interior of Greenland at a distance greater than 75 miles from the coast.

A great amount of valuable information concerning the glacial conditions of Greenland is to be found in the "Meddelelser om Gronland," a Danish publication, but containing many summaries in French or English. For a good account of the phenomena seen in the coastal region of the west coast, see Drygalski, "Gronland-Expedition," a large monograph published by the Gesellschaft fur physischen Erdkunde, Berlin, 1897.]

24 (return)
[ The argument is here considerably understated. The southern point of Greenland, Cape Farewell, is in the same latitude as the Shetland Islands and Christiania, and only one degree north of Stockholm; Disko is in about the same latitude as the North Cape. Hence the inhabited portion of Greenland is in the same latitude as Norway and Sweden, both fertile and well-populated countries. Even in Central Norway, in the Gudbrandsdal and Romsdal, thick forests grow up to a height of at least 3000 feet above sea-level, a much greater elevation than trees now attain in the British Isles. This latter fact is probably to be attributed to the protective effect of thick snow lying throughout the winter.]

25 (return)
[ For a summary of the most recent views as to the classification and succession of the glacial deposits of the British Isles, see Lake an Rastall, "Textbook of Geology," London, 1910, pages 466 to 473. Reference may also be made to Jukes-Browne, "The Building of the British Isles," London, 1912, pages 430 to 440.]

26 (return)
[ Glacier-lakes are fairly common among the fjords of the west coast of Greenland, and illustrate very well what must have been the state of affairs in Glen Roy at the time of formation of the Parallel Roads.]

27 (return)
[ The high-level shell-bearing deposits of Moel Tryfan, Gloppa, near Oswestry, and Macclesfield, have given rise to much controversy between the supporters of submergence and of land-ice. At Moel Tryfan certain sands and gravels, with erratics, at a height of about 1350 feet, contain abundant marine shells, generally much broken. The northern or seaward face of the hill is much plastered with drift, but none is to be found on the landward side, and it is suggested that the shell-bearing material is the ground-moraine of a great ice-sheet that came in from the Irish Sea, and was forced up on to the Welsh coast, just reaching the watershed, but failing to overtop it. With regard to the explanation by submergence, the great objection is the absence of marine drift on the landward side, which is very difficult to explain if the whole had been submerged sufficiently to allow of normal marine deposits at such a great height. The shell beds of Macclesfield and Gloppa are at a less elevation but of essentially similar character.

The shell-bearing deposits of Moel Tryfan were examined by a committee of the British Association. (See "Report of the British Association" Dover, 1899, pages 414 to 423.) At the end of this report is an extensive bibliography.]

28 (return)
[ During the last forty years the deep-sea dredging expeditions of H. M.S. Challenger and others have shown the abundance and variety of animal life at great depths, especially in the Arctic and Antarctic seas. For a recent summary, see Murray and Hjort, "The Depths of the Ocean," London, 1912.]

29 (return)
[ It is now generally admitted that these shell-beds in Wexford are of Pliocene age, and they therefore have no bearing on the subject under discussion.]

30 (return)
[ The boulder deposit at Selsey has been described by Mr. Clement Reid ("Quarterly Journal of the Geological Society," volume 48, 1892, page 355). Immediately above the Tertiary beds is a hard greenish clay, full of derived Tertiary fossils and Pleistocene shells with large flints and erratic blocks, some of the latter weighing several tons. They include granite, greenstone, schist, slate, quartzite, and sandstone, and most of them must have been transported for a long distance. Above them are black muds with marine shells, then a shingle beach, and above all the Coombe Rock. (See next note.)]

31 (return)
[ The Brighton elephant-bed and its equivalent, the Coombe Rock, are fully described by Clement Reid ("On the Origin of Dry Chalk Valleys and the Coombe Rock," "Quarterly Journal of the Geological Society," volume 43, 1887, page 364). The Coombe Rock is a mass of unstratified flints and Chalk debris filling the lower parts of the dry valleys (Coombes) of the South Downs and gradually passing into the brick-earth (loam) of the coastal plain. It is clearly a torrential accumulation, and is supposed to have been formed while the Chalk was frozen, thus preventing percolation of water and causing the surface water to run off as strong streams. This must have occurred during some part of the glacial period, which would naturally be a period of heavy precipitation. Of very similar origin is the "Head" of Cornwall, a surface deposit often rich in tinstone and other minerals of economic value. The Coombe Rock has recently been correlated with deposits of Mousterian Age.]

32 (return)
[ The former extension of the Alpine glaciers and the deposits formed by them have been exhaustively investigated by Penck and Bruckner ("Die Alpen im Eiszeitalter," 3 volumes, Leipzig, 1901 to 1909). In this monumental work the authors claim to have established the occurrence of four periods of advance of the ice, to which they give the names of Gunz, Mindel, Riss, and Wurm glaciations, with corresponding interglacial genial episodes, when the climate was possibly even somewhat warmer than now. Their conclusions and the data on which they are established are summarised by Sollas (" Ancient Hunters," London, 1911, especially pages 18 to 28). For a general account of the glaciers of the Alps and their accompanying phenomena, see Bonney, "The Building of the Alps," London, 1912, pages 103 to 151.]

33 (return)
[ At the time of the maximum advance of the ice, during the Riss period of Penck and Bruckner, the terminal moraine of the great glacier of the Rhone extended as far as the city of Lyon, and towards the north-east it became continuous with the similar moraine of the Rhine glacier.]

34 (return)
[ For the successive phases of advance and retreat of the Alpine glaciers, see the works quoted in Note 32.]

35 (return)
[ The Loess of Central Europe includes deposits of two different ages. According to Penck the "Older Loess" was formed in the period of warm and dry climate that intervened between the third and fourth glacial episodes, while the "Younger Loess" is post-glacial. Both divisions are for the most part aeolian deposits, formed by the redistribution of fine glacial mud originally laid down in water and carried by the wind often to considerable heights. A part, however, of the so-called Loess of northern France, e.g. in the valley of the Somme, is rain-wash, similar in character to the brick-earth of parts of south-eastern England. The Older Loess contains Acheulean implements, while the Younger Loess is of Aurignacian Age.

The greatest development of the Loess is in Central Asia and in China. (See Richthofen, "China," Berlin, 1877.) In China the Loess reaches a thickness of several thousand feet, and whole mountain-ranges are sometimes almost completely buried in it. In the deserts of Central Asia the formation of the Loess is still in progress. A very similar deposit, called adobe, is also found in certain parts of the Mississippi valley.

The Loess is a fine calcareous silt or clay of a yellowish colour, quite soft and crumbling between the fingers. However, it resists denudation in a remarkable manner, and in China it often stands up in vertical walls hundreds of feet in height. This property is probably assisted by the presence of numerous fine tubes arranged vertically and lined with calcium carbonate; these are supposed to have been formed in the first place by fibrous rootlets.]

36 (return)
[ Although highly probable, it cannot yet be regarded as conclusively demonstrated that the Pleistocene glaciations of Europe and of North America were exactly contemporaneous. The ice—sheets in each case radiated from independent centres which were not in the extreme north of either continent, and were not in any way connected with a general polar ice-cap. The European centre was over the Baltic region or the south of Scandinavia, and the American centre in the neighbourhood of Hudson's Bay. The southern margin of the American ice-sheet extended about as far south as latitude 38 degrees north in the area lying south of the Great Lakes, whereas the North European ice barely passed the limit of 50 degrees north in Central Europe. This greater southward extension in America was doubtless correlated with the same causes as now produce the low winter temperatures of the eastern states, especially the cold Newfoundland current. The literature of North American glacial geology has now attained colossal dimensions, and it is impossible to give here even a short abstract of the main conclusions. For a general summary reference may be made to Chamberlin and Salisbury, "Geology," volume 3; "Earth History," London and New York, 1905; or the same authors' "Geology, Shorter Course," London and New York, 1909.]

37 (return)
[ During the last fifty years scarcely any geological subject has given rise to a greater amount of speculation than the cause of the Ice Age, and the solution of the problem is still apparently far off. The theories put forward may for convenience be divided into three groups, namely astronomical, geographical, and meteorological.

As examples of astronomical explanation, we may take the well-known theory of Adhemar and Crohl, which is founded on changes in the ellipticity of the earth's orbit. This is expounded and amplified by Sir Robert Ball in his "Cause of an Ice Age." The weak point of this theory, which is mathematically unassailable, is that it proves too much, and postulates a constant succession of glacial periods throughout earth-history, and for this there is no evidence. The geographical explanations are chiefly founded on supposed changes in the distribution of sea and land, with consequent diversion of cold and warm currents. Another suggestion is that the glaciated areas had undergone elevation into mountain regions, but this is in conflict with evidence for submergence beneath the sea in certain cases. Meteorological hypotheses, such as that of Harmer, founded on a different arrangement of air pressures and wind-directions, seem to offer the most promising field for exploration and future work, but it is clear that much still remains to be explained.]

38 (return)
[ The reptile-bearing Elgin Sandstones are of Triassic Age, and they contain a most remarkable assemblage of strange and eccentric forms, especially Anomodont reptiles resembling those found in the Karroo formation of South Africa.]

39 (return)
[ The meaning of this statement is not very clear. The Conifers are not dicotyledons: their seeds contain numerous cotyledons, up to twenty in number, and the whole plant, and especially the reproductive system, belongs to a lower stage of development. The argument here employed is therefore fallacious, and in point of fact the different groups actually appeared in the order postulated by the theory of evolution, namely: (1) Gymnosperms, (2) Monocotyledons, (3) Dicotyledons. See Arber, "The Origin of Gymnosperms," "Science Progress," volume 1, 1906, pages 222 to 237.]

40 (return)
[ The part of the manuscript read to Dr. Hooker in 1844 was undoubtedly the "Essay of 1844," forming the second part of the "Foundations of the Origin of Species," a volume published by Sir Francis Darwin on the occasion of the Darwin Centenary at Cambridge in 1909. (See also Darwin's "Life and Letters," volume 2 pages 16 to 18.)]

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[ This projected larger work, which is often referred to in the "Origin of Species," was never published as such, but Darwin's views on various aspects of evolution were set forth in several later books, such as "The Variation of Animals and Plants under Domestication," "The Descent of Man," "Various Contrivances by which Orchids are Fertilised by Insects," "Movements and Habits of Climbing Plants," "Insectivorous Plants," and others.]

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[ With this section compare the famous chapter with the same title in the "Origin of Species."]

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[ No attempt has been made to annotate this chapter, owing to the impossibility of doing so within reasonable compass. Many of the theories here quoted, and the conclusions drawn from them, have not stood the test of time, and recent philological and ethnographical research have clearly shown the danger of attempting to infer the relationships of different peoples from their languages. The modifications undergone by the languages themselves are also subject to influences of such complex character, so largely artificial in their origin, that any attempt to compare them with natural evolution in the organic world must lead to false analogies. The chapter must be regarded as an interesting exposition of one phase of Mid-Victorian scientific thought, but having little real bearing on the subjects discussed in the rest of the book.]

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[ That the prophecy here given was justified is shown by the discovery in Java in 1891, of the skull and parts of the skeleton of Pithecanthropus erectus, a form which, according to the best authorities, must be regarded as in many ways intermediate between man and the apes, though perhaps with more human than ape-like characteristics. For an account of the circumstances of its discovery and a general description of the remains, see Sollas, "Ancient Hunters," London, 1911, pages 30 to 39 (with many references). Within the last year or two interest in the ancestry of man has been greatly increased, especially by the Piltdown discovery (see Note 11). This has led to a revision of the whole subject, and the views formerly held have undergone a certain amount of modification. It now seems certain that the different types of culture as represented by the succession of stages given in Note 12 do not correspond to a continuous development of one single race of mankind. There is, undoubtedly, a great break between the Mousterian and Aurignacian. Mousterian or Neanderthal man appears to have become extinct, possibly having been exterminated by a migration of the more highly developed Aurignacian race, which may be regarded as the ancestor of modern man in Europe. It appears, therefore, that the really important line of division comes, not as was formerly thought between Palaeolithic and Neolithic, but in the middle of the Palaeolithic between Mousterian and Aurignacian. Hence it appears that our classification will in the near future have to undergo revision, since the stages of culture from Aurignacian to Azilian show a much closer affinity to the Neolithic than they do to the earlier Palaeolithic. At the present time scarcely sufficient data are available to determine the relationship of Pithecanthropus and Eoanthropus to the later types of man. For an excellent summary of the most recent views see Thacker, "The Significance of the Piltdown Discovery," "Science Progress," volume 8, 1913, page 275.]