Chapter 12

[F11]R. S. Lull, ‘American Journ. of Science.’ 1907.

North America during Eocene times “was clad with forests in which grew both evergreen and deciduous trees distinctly modern in character. The moist climate gave rise to many streams and lakes, along the shores of which grew sedgy meadows that in turn gave rise to grassy plains.”[F11]In the following (Oligocene) period similar conditions for a time prevailed, but later, owing to the increasing aridity, broad meadow-lands and prairies made their appearance. The new environment produced larger and more active flesh-eaters, fleeter and more intelligent horses. One of the new and improved species isMesohippus bairdi, an 18-inch horse withonly a splint-like metacarpal representing the outer or fifth digit—a digit complete in all the Eocene horses. In this as in all the other Oligocene horses three of the four premolars, as in the recent Equidæ, resembled molars. Small and slender-limbed,Mesohippus bairdiwas adapted for living in the open, but a larger species (Mesohippus intermedius) might be described as a “forest” horse,—though only 24 inches high, this forest-dwelling form had as long cannon-bones as a 33-inch Shetland pony of the “forest” or cart-horse type. Another American Oligocene type (Miohippus) from Oregon deserves mention, not so much because it was more specialised, but because it had a representative (probably a descendant) in Europe known asAnchitherium, which in Miocene times ranged from France to Bavaria. In this European species the last vestiges of the first and fifth digits had apparently disappeared. The fore limb ofMesohippusis represented in fig. 18, and a restoration is given in fig. 14.

It is impossible to say how many thousands of years are represented by the Eocene and Oligocene deposits, but an idea of the time that has elapsed since the beginning of the Tertiary period will be gained if it is mentioned that “when the fox-likeHyracotheriumwas wandering on the marshes of Kent not only was the Himalaya non-existent, but that along the line of its very heart—where the kiang now lives at an elevation of from thirteen thousand to sixteen thousand feet—extended an arm of the sea of no inconsiderable depth.”[F12]

[F12]Lydekker, ‘The Horse and its Relations,’ p. 242.

During the Miocene period the horse passed through the most interesting phases of his evolution, his elaborate dental battery was almost brought to perfection, and the second and fourth toes were gradually dwarfed and hidden out of sight, not even a trace of the hoofs being left, as in sheep, to suggest polydactylous ancestors. As already hinted, though Europe was the birthplace of theremote ancestor of the Equidæ, it is in the Miocene deposits of North America that we have a record of the most important phases of their evolution. The remarkable progress made in Miocene times was doubtless necessary to enable horses and other grass-eaters to keep abreast of the profound changes in the environment—the great increase of prairies in some areas, and the upheavals which resulted in the appearance of extensive mountain ranges in others.

The Oligocene species which proved sufficiently plastic to respond to the new conditions varied in different directions, and gave rise to, amongst other types, one well adapted for a forest life, and one highly specialised for ranging far and wide over boundless prairies.

InHypohippuswe have an example of a “forest” horse, in the AmericanHipparion(Neohipparion) we have a horse more specialised for a desert life than the fleetest Arab, while inMerychippuswe have a link withOligocene species deserving attention, because, on the one hand, it gave rise throughNeohipparionto theHipparions, now extinct, but once common in Europe and Asia; and because, on the other hand, throughProtohippusit seems to be the ancestor of the slender-limbed species of the “desert” or plateau type, now best represented by Celtic and Mexican ponies.

InMerychippusthe orbit is complete, and the crowns of the permanent molars are cemented as in recent horses, but the hoof bone has a cleft at the apex (fig. 19), and in some cases there is a minute vestige of the “splint” bone of the fifth or outer digit of the fore-foot. In fig. 11a, the fore-foot ofNeohipparion, the Miocene race-horse, is represented. Fig. 19 gives the fore-foot, and fig. 16 is a restoration ofMerychippus.

HithertoMerychippus, throughProtohippusandPliohippus, has been by many regarded as the progenitor of all the modern horses, as well as of the extinctHipparions. Thatslender-limbed horses with short-pillared molars are mainly descended from one or more varieties ofMerychippusis possible, but it seems to me that modern breeds with short broad cannon-bones and long-pillared molars are probably mainly descended from browsing ancestors with limbs of theHypohippustype.

Hypohippus, likeEohippus, but unlike all the known Oligocene horses, had in the fore limb, in addition to three complete and functional toes, a distinct vestige of the first metacarpal—i.e., of the bone which in man carries the thumb. No vestige of a first metacarpal has ever been found in slender-limbed breeds, but once and again a vestige of the first metacarpal occurs in coarse-limbed breeds. The vestigial first metacarpal, taken along with other facts, suggests, as already said, that coarse-limbed breeds include a browsing race with limbs of theHypohippustype amongst their ancestors. A few years ago it was assumed thatHypohippus, the40-inch forest horse of Dakota and Montana, became “extinct during the Miocene, leaving no descendants.”[F13]Now, however, it is admitted that browsing horses possibly “identical withHypohippusof the Miocene of America”[F14]lived in China at the beginning of the Pliocene. Though it is inconceivable that a species with the short-crowned teeth ofHypohippuscould give rise to any of our modern breeds, it is possible that in the Pliocene of Eastern Asia a race (withHypohippus-like limbs but long-crowned molars) may be found bearing the same relation to long, low, big-boned modern “forest” horses thatMerychippusbears to fine-boned modern plateau or desert horses.

[F13]Lull,loc. cit., p. 177.

[F14]Osborn, ‘Age of Mammals,’ p. 333.

The fore-foot ofHypohippusis represented in fig. 20. When a toe corresponding to the second digit ofHypohippus(II. fig. 20) appears in a modern horse it has sometimes, as inHypohippusandEohippus(I. fig. 10), a vestige of the first metacarpal at its upper. Fig. 15 is a restoration ofHypohippus.

Ponies in Prehistoric Times.—During the Pleistocene period some eight or more species of true horses and ponies inhabited North America. Apparently before Palæolithic man reached the New World all these American species had become extinct. About the American true horses which, likeHipparion, reached and found a home in Eastern Asia, very little is known. Some of their descendants found their way during Pliocene times into India; others reached south-eastern Europe.

One of the Indian Pleistocene species (E. namadicus) from the Narbada valley had large long-pillared molars likeE. complicatusof North America andE. fossilisof England (fig. 22); another (E. sivalensis), well represented in Pliocene deposits of the Indian Siwaliks, is the oldest true horse about which we have definite information. LikePliohippus,E. sivalensishad short-pillared molars, but instead of measuring, likePliohippus, 12 hands at the withers, this Indian species reached, in some cases, a height of 15 hands.

Some of the Kirghiz breeds, in which the face is strongly bent downwards on the cranium, probably include this ancient Siwalik race amongst their ancestors. Some of the Eastern races which reached Europe[F15]in pre-glacial times found a congenial home in Tuscany and Umbria. Others, moving in a north-western direction, found their way into Britain, while others crossed by one or more land connections into North Africa. About the late Pleistocene descendants of the varieties and species which reached Europe before the Ice Age, a considerable amount of information has been gained from engravings and coloured drawings on the walls of caves occupied by Palæolithic man, and from fragments of skulls, teeth, and limb-bones foundin Pleistocene deposits. Up to the end of last century naturalists, as a rule, assumed that the wild horses hunted during the Early Stone Age all belonged to the same species, the so-called (E. fossilis), and when about 1870 Prjevalsky discovered wild horses in Mongolia, it was further assumed that these wild herds were the descendants ofE. fossilis, and hence represented the wild species from which all the modern domesticated breeds had sprung.

[F15]The horses which reached Europe in Pliocene times are usually said to belong to one species (E. stenonis).

Partly from fossil teeth and limb-bones, and partly from the engravings on the walls of caves and on pieces of horn, the conclusion was arrived at thatE. fossilis, the assumed common ancestor of modern breeds, was characterised by a large coarse head, coarse limbs, and long-pillared molars (fig. 22). Prjevalsky’s horse when first discovered was said to be characterised by coarse limbs as well as by a large heavy head. As it was further assumed a generation ago that all domestic horses had long-pillared molars, and that the cannon-bones varied with the surroundings—being short and broad in some areas, long and narrow in others—there seemed no escape from the conclusion that all the horses now living under domestication are descended from one and the same wild Pleistocene ancestor.

But though in Prjevalsky’s horse the head is coarse, the limbs are nearly as fine as in thoroughbred race-horses, and though in horses of the Prjevalsky or steppe type the pillars of the molars are long, they are not long in all modern horses. Moreover, though there is evidence of the existence in Europe in prehistoric times of a species with a coarse head and relatively fine cannon-bones, there is no evidence of the existence of a species which combined a coarse head with short broad cannon-bones. On the other hand, it has been ascertained that since Miocene times there have been living side by side in Europe big-boned and fine-boned species, and that, except by dwarfing, long narrow cannon-bonesare rarely if ever transformed into short, broad cannon-bones.

The skulls from the Roman military station at Newstead proved conclusively that there lived in Scotland during the first century large and small horses withshort-pillaredmolars (fig. 23). This led to the discovery that in Shetland and other ponies of the Celtic type, and in Arabs and thoroughbreds of the Libyan or Siwalik type, some of the molars have as short pillars as inE. stenonis(fig. 21) of the Val d’Arno Pliocene deposits.

The investigations of the last decade having indicated that during the Ice Age in Europe, as in America, there were always several species of horses living contemporaneously, an attempt must be made to ascertain from which of the wild prehistoric species Shetland ponies are mainly descended. In addition to steppe horses of the Prjevalsky make and horses allied in skull, teeth, and limbs toE. sivalensisof India, there were in prehistoric times large and small varieties of browsing or foresthorses, and “Celtic” and “Libyan” varieties of slender-limbed plateau or desert horses. Although trees and plateaus are conspicuous by their absence in the northern islands, the study of Shetland ponies makes it evident that they have mainly sprung from “forest” and “plateau” ancestors. Evidence of this we have in the limbs and skull as well as in the teeth. A fairly accurate estimate of the type to which a horse belongs, and also of its height, can often be gained from a study of the cannon-bones. For example, in 12-hands ponies of the “Celtic” variety the metacarpals are on an average 200 mm. long and 26·6 mm. wide at the middle of the shaft, whereas in 12-hands ponies of the “forest” type the length is on an average 193 mm. and the width 35 mm.—i.e., in the one case the length is 7·5 times the width, in the other only 5·5 times. In Preglacial times there were horses in Umbria with metacarpals 190 mm. by 32 mm., and horses with metacarpals 220 mm. by 30 mm. The 190 mm.metacarpals probably belonged to a long, low, broad-browed 12-hands “forest” pony, while the 220 mm. metacarpals doubtless belonged to a 13-hands fine-limbed pony of the “desert” type. During the Glacial period horses of the “forest” and “desert” as well as of the “steppe” type were common all over Europe.[F16]From the “Elephant-Bed” at Brighton bones of a 12-hands “forest” horse have been recovered. Kent’s Cavern, Torquay, in addition to the bones of a 12-hands “forest” horse, has produced cannon-bones of the same size and width as the fine-boned 13-hands Umbrian pony.

[F16]In the vicinity of an open-air settlement to the north of Lyons there are rubbish-heaps said to contain the remains of over 50,000 horses, which served as food during the Solutrian period of the Stone Age.

The “Elephant-Bed” and Kent’s Cavern small “forest” horses are best represented to-day by the long, low, broad-browed Iceland ponies, while the 13-hands small fine-boned race of Kent’s Cavern is best represented by Exmoor and other ponies of the “Celtic”type—i.e., by ponies with short-pillared molars, and only two of the eight callosities (chestnuts and ergots) invariably found on typical “forest” horses. Whether modern Shetland ponies are mainly descended from prehistoric British races or from a Norse race of the fjord type it is impossible to say. The Magdalenians, who occupied Kent’s Cavern while hunting the reindeer in the south of England towards the close of the Old Stone Age, had no domestic animals. Neither had their successors, the Azilians, who some 8000 years ago frequented the MacArthur and other caves near Oban. The Mediterranean race (now best represented by the Basques), which followed in the wake of the Azilians, perhaps brought sheep or cattle into Britain, but there is no evidence that they possessed horses. Professor Ridgeway believes “the use of the horse by man in the British Islands cannot be placed before the end of the Bronze or the beginning of the Iron Age.”[F17]

[F17]‘Origin and Influence of the Thoroughbred Horse,’ p. 92.

Through the courtesy of Sir William Turner I recently had the opportunity of examining some horse, sheep, and dog bones found near Grangemouth 30 feet below the surface, at the point where the Carron joins the Forth. Two imperfect horse skulls belonged to ponies of the “forest” type, which probably measured 12 hands at the withers, a broken sheep skull belonged to a member of the peat or turbary race, and a dog skull differed but little from that of a modern greyhound. Taking into consideration the position and nature of the deposit, one may provisionally assume that the bones belong to animals which lived in the Forth valley about the end of the Neolithic Age,—the dog and sheep undoubtedly lived under domestication, but whether the horses were tame or wild is uncertain.

The next horse bones from Scotch deposits available for study consisted of the skulls and limb-bones from Newstead, already referred to. Several of the horses in the possessionof the Roman auxiliaries who garrisoned the Border Fort in the first century were over 15 hands, and had the face bent downwards on the cranium as in Kirghiz horses,—in one case the deflection is so great that the hard palate forms an angle of nearly 20´ with the cranium (in the forest horse the face is in a line with the cranium). In one of the bent skulls the molars have as short pillars as inE. stenonis(fig. 21) of the Italian Pliocene.[F18]Two of the Newstead skulls belong to ponies about 12 hands high, one to a pony, Arab-like in make, with metacarpals measuring 214 mm. by 28·8 mm.—i.e., to a fine-boned pony about 13 hands at the withers. The skull and teeth of the 12-hands ponies indicate that one was about two-thirds “forest,” the other two-thirds “Celtic”; the teeth as well as the skull and cannon-bones of the 13-hands pony indicate that it was nearly a pure member of the Celtic or Libyan race.According to Dio Cassius, the Caledonians “went to war on chariots as their horses were small and fleet.” The two 12-hands Newstead ponies were probable members of the race which the Caledonians, Mætæ, and other tribes of northern Britain yoked to their war chariots. It is conceivable that soon after the Roman period ponies were taken from the mainland of Scotland to both the Western and Northern Islands. That ponies, resembling in make and size the small Newstead horses, reached Shetland some centuries before the northern islands fell into the hands of the Norsemen, is suggested by a broken pelvic bone belonging to a pony between 11 and 12 hands, found in 1911 at the Jarlshoff broch, Sumburgh, by Mr Charles M. Douglas. During the autumn of 1912, by permission of Mrs Bruce of Sumburgh, and with the help of Mr Bennet Clark, I examined a number of old hearths at Jarlshoff, probably formed about the same time as the deposit inwhich Mr Douglas found the broken pelvic bone.

[F18]Until the Newstead skulls were found it was believed horses with short-pillared teeth became extinct thousands of years ago.

The bones of the Celtic shorthorn and of turbary sheep, the presence of hammer-stones, pieces of pottery and scrapers, of limpet and other shells, together with the bones and implements collected during the excavations by the late Mr John Bruce of Sumburgh, support Mr Douglas’s view that horses reached Shetland some centuries before the turbulent Norse jarls, harassed by Harold Fairhair, began to settle in the Northern and Western Islands of Scotland.

It may hence be assumed that Shetland ponies are mainly descended from the “small and fleet” race yoked to the chariots of the Caledonians at the battle of Mons Graupius. This ancient race (which was probably brought to Britain during the late Celtic period) was probably originally a blend of the slender-limbed, Arab-like ponies of the Swiss Lake-dwellers and of a thick-set race of the Elephant-Bed type. That the Shetlandblend is an old one is suggested by the account Herodotus gives of the horses belonging to a tribe on the north of the Danube. This tribe (the Sigynnæ), Herodotus says, “had horses with shaggy hair, five fingers long, all over their bodies, and which were small and flat-nosed, and incapable of carrying men,[F19]but when yoked under a chariot were very swift, in consequence of which the natives drove in chariots.” Judging by this description, the chief difference between typical modern Shelties and the small horses of Central Europe in the time of Herodotus is a difference of size.

[F19]Herodotus probably means these small horses were incapable of carrying men into battle.

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