My Love For Horses
INTRODUCTION Horse, common name for hoofed, herbivorous mammals that include the domestic horse and three groups of undomesticated species. One group comprises the zebra, native to Africa; another consists of the ass, including the kiang and onager of Asia and the wild ass of Africa. The third group contains Przewalski's wild horse, which is now found only in captivity. The only extant true wild horse, it produces fertile offspring when crossed with the domestic horse. Other so-called wild horses in various parts of the world, such as the mustang in North America, are descendants of domestic horses that have reverted to a wild state. IIPREHISTORIC HORSES The evolution of the horse can be traced through fossil remains to the Hyracotherium, originally identified as the Eohippus: a small, leaf-browsing mammal of the Eocene Epoch, 55 million to 38 million years ago. Hyracotherium, about the size of a fox, had four toes on its forefeet and three on its hind feet. Several species and related genera appeared in North America and Eurasia during the Eocene. Then, apparently, the Eurasian species died out, but the American species gave rise in the Oligocene Epoch, 38 million to 24 million years ago, to the genus Mesohippus. In the Miocene Epoch, 24 million to 5 million years ago, Mesohippus was succeeded by Hypohippus and Anchitherium. Both of these genera probably migrated to Eurasia from North America. Other descendants of Mesohippus were Miohippus and Merychippus; the latter genus developed high- crowned teeth, permitting it to feed by grazing on grass rather than browsing on leaves. Among the descendants of Merychippus in the Pliocene Epoch were Hipparion, which apparently spread from North America to Eurasia, and Pliohippus, which appears to be the progenitor of the modern genus Equus, which includes the domestic horse. During the Pleistocene Epoch, which began 1.6 million years ago, the genus Equus apparently spread from North America to Eurasia, Africa, and South America. Subsequently, the native American horses died out, possibly as a result of disease. Cave dwellings in Europe indicate that horses were plentiful on that continent during the early Stone Age (about 2 million years ago to about 4000 BC). Dismembered skeletons of horses have been found in sufficient numbers in and near Stone Age dwellings to show that horses were frequently killed and eaten. In Neolithic times (about 4000 BC to 2000 BC), when Europe was largely forested, the number of horses evidently declined. Remains of the Bronze Age (about 1000 BC) include bits and pieces of harness, which clearly demonstrate that horses had become domestic animals in this period. IIIMODERN HORSES The most marked anatomical characteristic of the modern horse is the possession of a single toe on each of its four feet, which makes it a perissodactyl, or odd-toed ungulate, along with the rhinoceros and tapir. The horse's toe, which corresponds to the middle digit of the human hand, is much enlarged and protected by a horny hoof that surrounds the front and sides of the toe. Vestigial splints corresponding to the second and fourth toes are situated on either side of the foot above the hoof. The skull of the horse is long; the facial bones are twice the length of the cranium. The mandible, or lower jaw, is long and has a broad, flat plate at its lower hind end. The spine is composed of 7 cervical, 18 dorsal, 6 lumbar, 5 sacral, and 15 caudal vertebrae. Horses have 44 teeth: 3 incisors, 1 canine, 4 premolars, and 3 molars on each side of each jaw. The incisors, which are used for cropping grass and other herbage, grow in the form of a semicircle. A pronounced gap exists between the canine teeth and the premolars; the metal bit used for controlling a horse is placed in this gap when the animal is ridden or driven. All the teeth have long crowns and comparatively short roots. The horse has a simple stomach, and fermentation of fibrous food takes place in a blind pocket, or cecum, analogous to the appendix in humans. It is located at the juncture of the small and large intestines. In a large horse the cecum may have a capacity of about 38 liters (about 10 gallons). Both male and female horses are sexually mature by the age of two. They are seldom used for breeding purposes, however, before they are three years old. The gestation period is about 11 months, and single births are the rule. Twins are a genuine rarity, and only a few births of three or more foals have ever been recorded. IVGAITS Horses are capable of a wide range of gaits; a few of them are artificially developed by trainers. For simplicity they may be divided into symmetrical gaits, in which equal time intervals separate the touching of the ground by the left and right front legs (and also by the left and right hind legs); and asymmetrical gaits, in which the time intervals are not equal. Familiar symmetrical gaits, in order of increasing speed, include the walk, pace, and trot. A horse walks by swinging its legs in the order of left front, right rear, right front, and left rear. It paces winging the left and then the right legs nearly in on, and trots by swinging the diagonally opposite nearly in unison. Artificial symmetrical gaits ude the slow gait, or stepping pace, and the er rack, or single-foot, both of which are done legs lifted high and no more than two legs on the nd at the same time. Asymmetrical gaits include er and the faster gallop, in which the left and ,he right hind leg touches the ground, followed by left and then the right front leg; the sequence be reversed right to left. DS AND BREEDS Domestic horses were introduced into lonia in about 2000 BC and into Egypt about 300 s later. The animals were brought into Egypt by Hyksos from northeastern Syria. These Egyptian and lonian horses were the forerunners of the swift Arabian and related desert breeds of the Middle East and northern Africa. Another strain of horses was domesticated in Europe. Heavily built and slower but more powerful than the desert breeds, they are regarded as the early ancestors of the modern draft horses used for plowing, pulling wagons, and other heavy work. Some authorities also believe that a third ancestral strain found in the British Isles was the prototype of various breeds of modern ponies. Throughout most of Europe, from the early centuries AD to about the 17th century, the powerful native horses were used for military mounts, for hauling heavy loads, and as pack animals. During the same period the Arab world had developed smaller, fast-galloping breeds, which were introduced into Spain after the Muslim conquest in the 8th century. The horses bred in Spain became famous for their speed and endurance and many were imported into England and Europe as early as the 12th century. Systematic attempts to improve extant breeds of horses, however, did not take place until the end of the 17th century, when Arabian stallions were imported to England and France to breed with mares of native stock. The first domestic horses introduced into the Americas were of the Arabian type, brought by the Spanish conquistadores and explorers in the 16th century. They are believed to have lost or abandoned some of their horses, and these animals may have been the source of herds of wild horses found in various parts of western North America. Horses left by the Spanish also ran wild on the pampas of South America around the Río de la Plata. The English settlers, especially the early Virginia colonists, also imported horses. In the last 300 years horse breeders have made continuous attempts to improve the various breeds of horses and to develop strains that are particularly suited for specialized tasks. The resultant new breeds include saddle horses and harness horses especially adapted for racing gaits, hunters adapted for endurance, carriage horses and draft horses for pulling heavy loads, and cattle horses, ponies, and polo ponies (small, fast animals that can be trained to the complicated maneuvers of roping or the game of polo). The Arabian breed is often divided into three subbreeds: Turks from European Turkey and Asia Minor, Arabians from the regions between Damascus and the Euphrates River, and Barbs from the Barbary states of northern Africa. Arabians in general are comparatively small horses, standing between 147 and 152 cm (58 and 60 in) at the withers (the high part of the back, located between the shoulder blades), or 15 hands high. The height of a horse is frequently given in hands, one hand-the width of a human hand-is equal to 10 cm (4 in). Arabians have remarkable powers of endurance and are swift gallopers. All the saddle breeds are derived, in large part, from Arabian stock. The Thoroughbred was developed in the early 18th century from offspring of three foundation sires- the Byerly Turk, the Darley Arabian, and the Godolphin Barb-and native English mares. It is primarily used for flat-track racing, hunting, and jumping. The American standardbred, developed in the northeastern United States in colonial times, is a light harness type and is most often used in trotting or pacing races. Biologically speaking, saddle horses are more properly types than breeds. Because of the popularity of various equestrian sports and activities, registry and breed associations have been established for such important show and racing horses as the American saddle horse, the Tennessee walker, the Morgan, and the quarter horse. Saddle horses weigh much less than draft horses. The breeds of draft horses are more distinct than those of saddle horses. They include the Belgian heavy draft horse, the English shire, the Clydesdale, and the Percheron. The Belgian is one of the largest of horses, reaching a shoulder height of 173 cm (68 in) or more and weights of as much as 1125 kg (2500 lb). The English shire is about the same size, but has long hair on the back of its hind legs from its hooves up to the hock (a joint corresponding to the human ankle, but bending backwards). These breeds represent refinements of the original horses of their countries of origin. The Clydesdale, smaller than the above breeds, was developed in Scotland by crossing native horses with Belgian heavy draft horses and the English shire. The Percheron, which stands about 168 cm (66 in) at the shoulder, is a native of the former district of Le Perche in northwestern France and was produced by crossing Arabian horses with the old Flemish breed of which the Belgian heavy draft horse is the modern representative. Ponies are identified as those breeds which stand less than 152 cm (60 in) or 15 hands high. The real differences between ponies and larger horses, however, are size and action. The body of a pony is deeper in relation to its height than that of a horse, and a pony usually is more sure-footed than a horse. Many ponies are native to Great Britain: the Dartmoor, the Exmoor, and the Welsh mountain pony for instance. The smallest of the ponies is the Shetland, which is only about 106 cm (about 42 in) high at the withers. Scientific classification: Horses belong to the family Equidae of the order Perissodactyla. The domestic horse is classified as Equus caballus. Przewalski's wild horse is classified as Equus caballus przewalskii. See also Horsemanship; Horse Racing. Further Reading "Horse," Microsoft® Encarta® Encyclopedia 99. © 1993-1998 Microsoft Corporation. All rights reserved.
 
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