Читать книгу Men of the Old Stone Age: Their Environment, Life and Art - Henry Fairfield Osborn - Страница 9

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Fig. 12. Europe in the period of maximum continental elevation, in which the coast-lines are widely extended, connecting Africa and Europe—including Great Britain and Ireland—in a single vast peninsula, and affording free migration routes for animal and human races north and south, as well as east and west. The ocean boundaries are more remote and the interior seas are greatly reduced in area. After Obermaier.

In general, the elevation of the continent took place during interglacial, the subsidence during glacial times, but Great Britain appears to have been almost continuously elevated and a part of the continent, and was certainly so during the Third Interglacial, Fourth Glacial, and Postglacial Stages, because there was a free migration of animal life and of human culture. The Lower Palæolithic peoples of Pre-Chellean and Chellean times wandered at will from the valley of the Somme to the not far distant valley of the Thames, interchanging their weapons and inventions. The close proximity of these stations is well illustrated in the admirable map (Fig. 56) prepared under the direction of Lord Avebury (Sir John Lubbock). The relation which elevation and subsidence respectively bear to the glacial and interglacial stages is believed to be as follows:

Elevation, emergence of the coast-lines from the sea, broad land connections facilitating migration, retreat of the glaciers, deepening of the river-valleys, and cutting of terraces. Arid continental climate and deposition of 'loess.'

Subsidence, submergence of the coast-lines and advance of the sea, interruption of land connections and of migration routes, advance of the glaciers, filling of the river-valleys with the products of glacial erosion, the sand and gravel materials of which the 'terraces' are composed, and subglacial erosion of the loam, from which in arid periods the 'loess' is derived.

Subsidence was the great feature of closing glacial times both in Europe and America. During the Fourth Glacial and Postglacial Stages the Black and Caspian Seas and the eastern portion of the Mediterranean were deeply depressed, while the British Isles were still connected with France, but by a narrower isthmus than that of early interglacial times. The scattered stations of Upper Palæolithic culture found in the British Isles include one Aurignacian, one Solutrean, two Magdalenian, and two Azilian; this shows that travel communication with the continent continued throughout that period, in all probability by means of a land connection. In late Neolithic times the English Channel was formed, Great Britain became isolated from Europe, and Ireland lost its land connection first with Wales and then with Scotland.

Changes of Climate

Penck(68) estimates the intensity of the cold and of the humidity which prevailed during the glacial stages by the descent of the snow-line in the Alps, which in the two periods of greatest glaciation reached from 1,200 m. (3,937 ft.) to 1,500 m. (4,921 ft.) below the present snow-level, with the consequent formation of vast ice-caps hung with glaciers which flowed great distances down the valleys of the Rhône and of the Rhine and left their moraines at very distant points. The moraines and drifts of the lesser glaciations, such as the first and fourth, stand considerably within the boundaries of these outer moraines and drift fields. On the contrary, the warmer climates of interglacial times are indicated by the sun-loving plants found at Hötting, along the valley of the Inn, in the Tyrol, which are proofs of a temperature higher than the present and of the ascent of the snow-line 300 m. (984 ft.) above the existing snow-level of the Alps.

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Fig. 13. An ideal earth section from the North Cape across the Scandinavian plateau, through the North Sea, Swiss Alps, Pyrenees, and Straits of Gibraltar, to the Atlas Mountains in northern Africa, along the line indicated on the map (Fig. 25, p. 65), illustrating the sea-level at the time of the greatest elevation of the continent during the Second Glacial Stage, as compared with the present sea-level; also the successive lines of descent of the region of perpetual snow during the four great glacial advances, as compared with the present snow-line. From studies by Dr. C. A. Reeds.

The alternation of the cold climates of the glacial stages with the warm temperate climates of the interglacial stages formed great oscillations of temperature (Figs. 13, 14). The fossil plant life indicates that during the periods of the First, Second, and Third Interglacial Stages the climate of western Europe was cooler than it had been during the preceding Pliocene Epoch and somewhat warmer than it is at the present time in the same localities. During the First, Second, and Third Glacial Stages there was certainly a marked lowering of temperature in the regions bordering the great glacial fields. This is indicated by the arrival in the northern glacial border regions of animals and plants adapted to arctic and subarctic climates.

It has been generally believed that the whole of western Europe was extremely cold during these glacial stages, and that the heat-loving animals, the southern elephants, rhinoceroses, and hippopotami, were driven to the south, to return only with the renewed warmth of the next interglacial stage.

There is, however, no proof of the departure of these supposedly less hardy mammals nor of the spread over Europe of the more hardy arctic and steppe types until the advent of the Fourth Glacial Stage. Then, for the first time, all western Europe north of the Pyrenees experienced a general fall of temperature, and conditions of climate prevailed such as are now found in the arctic tundra regions of the north and in the high steppes of central Asia, which are swept by dry and cold winter winds. Fluctuations of temperature, of moisture, and of aridity in Pleistocene time, are evidenced not only by the rise and fall of the snow-line and the advance and retreat of the ice-caps but also by the appearance of plant and animal life in the periods of the 'loess' deposition, indicating the following cycles of climatic change as witnessed from beginning to end of the Third Interglacial Stage:

IV. Glacial maximum, cold and moist climate, arctic and cold steppe fauna and flora.

Cool and dry steppe climate, wide-spread deposition of 'loess.'

Interglacial maximum, a long period of warm temperate forest and meadow conditions.

Glacial retreat, cool and moist climate bordering the glacial regions.

III. Glacial maximum, cold and humid climate bordering the glaciers, favorable to arctic and subarctic plant and animal life.

That great fields of ice and advancing glaciers alone do not constitute proof of very low temperatures is shown at the present time in southeastern Alaska, where very heavy snowfall or precipitation causes the accumulation of vast glaciers, although the mean annual temperature is only 10° Fahr. (5.56° C.) lower than that of southern Germany. Neumayr(69) estimated that during the Ice Age there was a general lowering of temperature in Europe of not more than 6° C. (10.8° Fahr.), and held that even during the glacial advances a comparatively mild climate prevailed in Great Britain. Martins(70) estimated that a lowering of the temperature to the extent of 4° C. (7.2° Fahr.) would bring the glaciers of Chamonix down to the level of the plain of Geneva. Penck estimates that, all the atmospheric conditions remaining the same as at present, a fall of temperature to the extent of 4° to 5° C. would be sufficient to bring back the Glacial Epoch in Europe. These moderate estimates entirely agree with our theory that animals of African and Asiatic habit flourished in western Europe to the very close of the Third Interglacial Stage, and that then for the first time the warm fauna, or faune chaude, gradually disappeared.

Similarly the hypothesis of extremely warm or subtropical conditions prevailing in interglacial times as far north as Britain, which originated with the discovery of the northerly distribution of the hippopotami and rhinoceroses, animals which we now associate with the torrid climate of Africa, is not supported by the study either of the plant life of interglacial stages or by the history of the animals themselves. It is quite probable that both the hippopotami and the rhinoceroses of the 'warm fauna' were protected by hairy covering, although not by the thick undercoating of wool which protected the woolly rhinoceros and woolly mammoth, animals favoring the borders of glaciers and flourishing during the last very cold glacial and Postglacial periods.

The combined evidence from all these great events in western Europe leads us to conclusions somewhat different from those reached by Penck as to the chronology of human culture. In the chart (Fig. 14) on the opposite page, prepared by Dr. C. A. Reeds in collaboration with the author, a new correlation of geologic, climatic, human, industrial, and faunal events is presented. The great waves of glacial advance and retreat (oblique shading) are based upon Penck's estimates of the rise and fall of the snow-line (vertical dotted lines) in the Swiss Alps. (Compare Fig. 13.) The length of these waves corresponds with the relative duration of the glacial and interglacial stages as estimated by the varying amounts of erosion and deposition of materials. The entire Palæolithic or Old Stone Age is thus seen to occupy not more than 125,000 years, or only the last quarter of the Glacial Epoch, which is estimated as extending over a period of 525,000 years. The present opinion of the leading archæologists of France and Germany, which is shared by the author, is that the Pre-Chellean industry is not older than the Third Interglacial Stage. As the Piltdown man was found in deposits containing Pre-Chellean implements, he probably lived in the last quarter of the Glacial Epoch, and not in early Pleistocene times as estimated by some British geologists. This causes us to regard the Piltdown remains as more recent than the jaw of Heidelberg, which all authorities agree is probably of Second Interglacial Age. According to our estimates the Heidelberg man is nearly twice as ancient as the Piltdown man, while Pithecanthropus (Trinil Race) is four times as ancient. Yet the Piltdown man must still be regarded as of very great antiquity, for he is four times as ancient as the final type of Neanderthal man belonging to the Mousterian industrial stage. The various archæologic and palæontologic evidences for this general correlation theory of the Glacial Epoch are fully discussed in the succeeding chapters of this volume.

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Fig. 14. Great events of the Glacial Epoch. To the left the relation of glacial and interglacial stages in Europe and North America, with the author's theory regarding the divisions of time, the beginning of the Old Stone Age, and the successive appearance in Europe of different branches of the human race. To the right the prolonged warm temperate period in Europe in the non-glaciated regions, followed by the relatively brief cold period during the past 70,000 years. Prepared by Dr. C. A. Reeds, in co-operation with the author.

Mammals of Five Distinct Geographic Regions

(Compare Color Map, Pl. II, and Fig. 15)

As we have already observed, during the whole history of mammalian life in various parts of the world never did there prevail conditions so unusual and so complex as those which surrounded the men of the Old Stone Age in Europe. The successive races of Palæolithic men in Europe were all flesh eaters, depending upon the chase. The mammals, first pursued only for food, utensils, and clothing, finally became subjects of artistic appreciation and endeavor which resulted in a remarkable æsthetic development.

From the beginning to the end of Palæolithic times the various races of man witnessed the assemblage in Europe of animals indigenous to every continent on the globe except South America and Australia and adapted to every climatic life-zone, from the warm and dry plains of southern Asia and northern Africa to the temperate forests and meadows of Eurasia; from the heights of the Alps, Himalayas, Pyrenees, and Altai Mountains to the high, arid, dry steppes of central Asia with their alternating heat of summer and cold of winter; from the tundras or barren grounds of Scandinavia, northern Europe, and Siberia to the mild forests and plains of southern Europe.(71) Members of all these highly varied groups of animals had been evolving in various parts of the northern hemisphere from the Eocene Epoch onward. In Pliocene times they had become thoroughly adapted to their various habitats. Throughout early Pleistocene times, with the increasing cold extending southward from the arctic circle, such mammals as the elephant, rhinoceros, musk-ox, and reindeer had become thoroughly adapted to the climate of the extreme north. There is every reason to believe that when these tundra quadrupeds first arrived in Europe, during early mid-glacial stages, they had already acquired the heavy coat of hair and undercoating of wool, such as now characterizes the musk-ox, one of the living representatives of this northern fauna.

MIGRATIONS AND EXTINCTIONS OF MAMMALIAN LIFE DURING THE

FOUR GLACIAL, THREE INTERGLACIAL, AND POSTGLACIAL STAGES

Recent Prehistoric.	Return of the Alpine Mammals to the Mountains.	Period of Recent Animals.
Wide dispersal of Forest and Meadow Mammals over the Northern Hemisphere.
	Retreat of the Tundra and Steppe Mammals to the North and East.	Reindeer Period IN Western Europe.
Postglacial. Severe climate.	Mingling in the lowlands of France and Germany of the Reindeer-Mammoth fauna, the Alpine fauna, the Steppe Mammals, and the hardy Eurasiatic Forest and Meadow Mammals.
IV. Glacial. Cold Steppe climate.	Arrival of the Tundra Mammals from the North.
Arrival of the Steppe Mammals from Western Asia.
	Southward migration and extinction of all the African-Asiatic Mammals except the lions and hyænas.
3dInterglacial. Warm climate.	Mingled African-Asiatic and Eurasiatic Mammals in different parts of the non-glaciated regions, the hippopotamus, southern mammoth, straight-tusked elephant, Merck's broad-nosed rhinoceros, lion, hyæna, jackal, sabre-tooth tiger.	Period OF THE Hippopotamus, Rhinoceros, AND Elephant. Also OF THE Stag AND Bison IN Western Europe.
III. Glacial.	Reindeer and Woolly Mammoth in North Germany and the Alps.
2d Interglacial.		Also the stag, giant deer, bison, wild cattle, forest horse, boar, wolf, fox, lynx, wildcat, several species of bear.
II. Glacial.	Reindeer and Woolly Mammoth in Northern Germany.
1st Interglacial.		Survival of many Pliocene African-Asiatic Mammals, mingled with Pliocene and recent Eurasiatic Forest and Meadow Mammals.
I. Glacial.	Musk-ox in Sussex, England.
Geologic and Climatic Stages.	Early Migrations of Scandinavian and North Siberian Mammals near the Ice-fields.	'Warm' African-Asiatic Mammals.	More hardy Eurasiatic Mammals.	Three Chief Life Periods.
Temperate and sheltered parts of Western Europe.	Cool temperate forests and meadows.
	Regions near the Ice-fields and Glacial Borders.	More Sheltered Non-Glaciated Regions Remote from the Glacial Borders and Ice-fields.

The five great sources of mammalian migration into western Europe in Pleistocene times were accordingly as follows:

1. Warm plains of northern Africa and of southern Asia. "African-Asiatic" fauna—hippopotamus, rhinoceros, elephant.

2. Temperate meadows and forests of Europe and Asia. "Eurasiatic" fauna—deer, bison, horse.

3. High, cool mountain ranges—Alps, Pyrenees, Caucasus, Urals. Fauna—chamois, ibex, ptarmigan. (See Fig. 185.)

4. Steppes and deserts. Dry, elevated plateaus and steppes of eastern Europe and central Asia. Fauna—desert ass and horse, saiga antelope, jerboa. (See Fig. 186.)

5. Tundras and barren grounds within or near the arctic circle. Fauna—reindeer, musk-ox, arctic fox. (See Figs. 95 and 96.)

(Compare Figs. 14 and 15.)

In the warm plains, forests, and rivers of southern Asia and northern Africa there developed the elephants, rhinoceroses, hippopotami, lions, hyænas, and jackals, which, taken together, may be known as the African-Asiatic fauna. It contains altogether fourteen species of mammals. The great geographic area from the far east to the far west over which ranged similar or identical species of these pachyderms and carnivores is indicated by the oblique lines in the geographic chart (Fig. 15).

The north temperate belt of Asia and Europe, with its hardy forests and genial meadows, was the home of the even more highly varied Eurasiatic Forest and Meadow fauna. This includes twenty-six or more species. Of these the red deer, or stag, was most characteristic of the forests and the bison and wild cattle[M] of the meadows. Even at the very beginning of Pleistocene times there appear the stag, the wild boar, and the roe-deer with their natural pursuers, the wolf and the brown bear. From the northern woods came the moose and the wolverene. Most of these mammals were so similar to existing forms that the older naturalists placed them in existing species, but the tendency now is to separate them or place them in distinct subspecies. Mingled with these forest and meadow mammals were a few others which have since become extinct, such as the giant deer (Megaceros), the giant beaver (Trogontherium), and the primitive forest and meadow horses. From this region also there developed the cave-bear (Ursus spelæus). Certainly it is astonishing to find the remains of these mammals mingled with those from southern Asia and Africa, as is frequently the case. In early glacial times the bison and wild cattle mingled freely with the hippopotami and rhinoceroses, but in late glacial and Postglacial times they occurred as companions of the mammoth and the woolly rhinoceros. In prehistoric times they survived with the mammals brought from the Orient by the Neolithic agriculturists.

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Fig. 15. Zoogeographic map. Range of the large mammals of Africa and southern Asia in Pliocene and Pleistocene times until nearly the close of the Lower Palæolithic (oblique lines). Range of the forest and meadow fauna of Europe and Asia from early Pleistocene to prehistoric times; stag and bison fauna (horizontal lines). Present range of the tundra or barren-ground mammals (dots) which wandered south during the fourth glaciation, expelling the large Asiatic mammals. Present range of mammals of the deserts and steppes of eastern Europe and southern Asia, which also invaded western Europe during the glacial and Postglacial stages (vertical lines). The alpine mammals dwelt in the high mountain regions and invaded the plains and lowlands during Fourth Glacial and Postglacial times.

During a great glaciation, but especially during the severe climate of late Pleistocene times, the Alpine mammals were driven down from the heights into the plains and among the lower mountains and foot-hills. Thus the ibex, chamois, and argali sheep from the Altai Mountains are represented both in drawing and in sculpture by the men of the Reindeer Period.

Still more remarkable is the arrival in Europe of the Steppe Fauna of Russia and of western Siberia, mammals which now survive in the vast Kirghiz steppes, east of the Caspian Sea and the Ural Mountains, where the climate is one of hot, dry summers and prolonged cold winters, with sweeping dust and snow storms. These animals are very hardy, alert, and swift of foot, such as the jerboa, the saiga antelope, the wild asses, and the wild horses, including the Przewalski type, which still survives in the desert of Gobi. From this region also came the Elasmothere (E. sibiricum), with its single giant horn above the eyes. Very distinctive of the fauna frequenting the caverns are the small rodents, including the dwarf pikas, the steppe hamsters, and the lemmings. These animals were attracted into Europe during the 'steppe' and 'loess' periods of cold, dry climate.

The advance of the great Scandinavian glaciers from the north crowded to the south the Tundra or Barren Ground fauna of the arctic circle. The herald of this fauna during the First Glacial Stage was the musk-ox, which appears in Sussex, and then came the reindeer of the existing Scandinavian type. These animals are followed by the woolly mammoth (E. primigenius) and the woolly rhinoceros (D. antiquitatis) with their panoply of hair and wool which had long been developing in the north. Finally in the Fourth Glacial Stage arrived the lemming of the river Obi, also the more northern banded lemming, the arctic fox, the wolverene, and the ermine, as well as the arctic hare. These tundra mammals for a short period mingled in places with survivors of the African-Asiatic fauna, such as Merck's rhinoceros and the straight-tusked elephant (E. antiquus). In general, they swept southward as far as the Pyrenees over country which had long been enjoyed by the African-Asiatic mammals, while the hippopotami and the southern elephants retreated still farther south and became extinct.

The only survivors of the great African-Asiatic fauna in Fourth Glacial and Postglacial times were the hyænas (H. crocuta spelæa) and the lions (Felis leo spelæa). The lion frequently appears in the drawings of the cavemen.

The various species belonging to these five great faunæ apparently succeed each other, and wherever their remains are mingled with the palæoliths, as along the rivers Somme, Marne, and Thames, or in the hearths of the shelters and caverns, they become of extreme interest both in their bearing on the chronology of man and on the development of human culture, art, and industry. They also tell the story of the sequence of climatic conditions both in the regions bordering the glaciers and in the more temperate regions remote from the ice-caps. Thus they guide the anthropologist over the difficult gaps where the geologic record is limited or undecipherable. The general succession of these great faunæ is illustrated in Fig. 14 and also in the above table.

(1) Lamarck, 1815.1.

(2) Schaaffhausen, 1858.1.

(3) Darwin, C., 1909.2.

(4) Lamarck, 1809.1.

(5) Lyell, 1863.1, pp. 84-89.

(6) Darwin, C., 1871.1, p. 146.

(7) Darwin, C., 1909.1, p. 158.

(8) Retzius, A., 1864.1, p. 27.

(9) Op. cit., p. 166.

(10) Broca, 1875.1.

(11) Schwalbe, G., 1914.1, p. 592.

(12) Cartailhac, 1903.1.

(13) Déchelette, 1908.1, vol. I.

(14) Reinach, S., 1889.1.

(15) Schmidt, 1912.1.

(16) Avebury, 1913.1.

(17) Eccardus, 1750.1.

(18) Mahudel, 1740.1.

(19) Buckland, 1824.1.

(20) Godwin-Austen, 1840.1.

(21) Christol, 1820.1.

(22) Schmerling, 1833.1.

(23) Boucher de Perthes, 1846.1.

(24) Op. cit.

(25) Rigollot, 1854.1.

(26) Lubbock, 1862.1.

(27) Avebury, 1913.1, pp. 2, 3.

(28) Lartet, 1861.1.

(29) Lartet, 1875.1.

(30) Breuil, 1912.7, p. 165.

(31) de Mortillet, 1869.1.

(32) Piette, E., 1907.1.

(33) Rivière 1897.1.

(34) de Sautuola, 1880.1.

(35) Schmidt, 1912.1.

(36) Bourgeois, 1867.1.

(37) Schmidt, op. cit., p. 5.

(38) Obermaier, 1912.1, pp. 170-174; 316-320; 332, 545.

(39) Charpentier, 1841.1.

(40) Agassiz, 1837.1; 1840.1; 1840.2.

(41) Morlot, 1854.1.

(42) Chamberlin, 1895.1; 1905.1, vol. III, chap. XIX, pp. 327-516.

(43) Salisbury, 1905.1.

(44) Penck, 1909.1.

(45) Leverett, 1910.1.

(46) Lyell, 1867.1, vol. I, pp. 293-301; 1877.1, vol. I, p. 287.

(47) Dana, 1875.1, p. 591.

(48) Walcott, 1893.1.

(49) Upham, 1893.1, p. 217.

(50) Heim, 1894.1.

(51) Sollas, 1900.1.

(52) Penck, 1909.1, vol. III, pp. 1153-1176.

(53) Geikie, 1914.1, p. 302.

(54) Reeds, 1915.1.

(55) Nüesch, 1902.1.

(56) Geikie, op. cit., pp. 111-114.

(57) Op. cit., p. 108.

(58) Huntington, 1907.1.

(59) Leverett, 1910.1.

(60) Obermaier, 1912.1, p. 132.

(61) Penck, 1908.1; 1909.1.

(62) Geikie, 1914.1, p. 312.

(63) Wiegers, 1913.1.

(64) Boule, 1888.1.

(65) Schuchardt, 1913.1, p. 144.

(66) Obermaier, 1909.2; 1912.1.

(67) Schmidt, 1912.1, p. 266.

(68) Penck, 1909.1, vol. III, p. 1168, Fig. 136.

(69) Neumayr, 1890.1, vol. II, p. 621.

(70) Martins, 1847.1, pp. 941, 942.

(71) Osborn, 1910.1, pp. 386-427.