HORSE, in a general sense, a member of the ungulate family Equidee; but in ordinary use the word designates the single domestic species (Equus caballus), the wild original of which is unknown. It is not decided, in fact, whether a single species, or more than one, was the source, nor where the domestication of the horse was first effected. The evolution of the species is elsewhere sketched. It is probable that at the dawn of civilization the wild an cestors of our modern horses roamed in bands over the whole extent of grassy uplands stretch ing from northern Africa to eastern Manchuria, on the steppes of Russia, and wherever in Europe open country might be found; and It is also probable that they were among the first animals which men killed for food and after= want captured and tamed in order to keep a supply of food under control. This act must have been one of the earliest steps toward community life and civilization. The oldest paintings and carvings left by the ancient in habitants of the valley of the Euphrates show that saddle-horses were familiar to them; and it is fair to suppose that the supremacy primi tively gained by the people of central Asia over other parts of the world was largely due to their use of horses in war, giving them a great advantage over unmounted tribes; but it was not until much later—probably no earlier than 2000 'Lc.— that the animal came into use in Arabia and Egypt, where before had been only camels and asses. So far as can be judged, these early Assyrian war-horses were rather small, robust, large-headed and shaggy beasts, much like Przewalsky's horse or the kiang. A very similar animal was domesticated by the men of the Polished Stone Age in Europe, ex cellent portraits of which were etched by neolithic artists upon pieces of bone, and have come down to us among the contents of graves opened by archmologists in France, Switzer land and elsewhere. Later, but still in the pre historic period, Europe was repeatedly invaded by Asiatic hosts who brought with them East ern horses. These modified, if they did not supersede, the local stock. When Rome con quered the barbarous inhabitants of Europe its horses, which were of Asiatic stock, with per haps some African mixture, lafgely super seded those of the conquered tribes, and from the mingling there sprang the big heavy breeds which characterized the Middle Ages, and were intended for strength and weight-carrying, rather than for nimbleness and speed. It was
not until near the end of the 17th century that the introduction into France and England of certain sires of Arabian breed—a clean limbed, small-headed, agile, hardy race, which arose in Arabia and icialestine about Z000 years ago — began the improvement of British stock, which has reached its highest development in the modern European racehorse, coach and hackney. The normal horse lives to about 18 or 20 years; he is not valued for stud after 20. Occasionally some live to 40 or 50 years. The long intestinal tract seems to operate against longevity. The term horse is applied to males of the Equus, as well as to the entire family. A stallion is a mature uncastrated male, also termed a stud-horse; a gelding is a castrated or unsexed male, it being customary to castrate all except those used for breeding. A mare is a female of the horse family. Right after birth the young animal is termed a foal, a little later a colt. The young mare is distin guished as a filly.
The horse owes his speed largely to his long, clean limbs, the advantageous angles made by the leg bones, and to the substitution of a single strong bone for the ulna and radius in other quadrupeds, together with the growth of a strong hoof out of a central toe, The joint corresponding to the knee in man is close to the body, while the horse's wrist-joint is 18 or 20 inches from the ground in a fair-sized ani mal's foreleg. The horse's hip or thigh joint is entirely imbedded within his muscular hip, and the knee-joint is close up to the body, while the ankle-joint of the hind leg is at the height of a mans knee. By walking and run ning on his toes, the horse has gained one more joint for leg action. The teeth of the horse are also peculiar. On each jaw of a mature horse are 6 incisors, 2 canines, 6 premolars and 6 molars; but most mares are minus the incisors. See HORSE, EVOLUTION OF THE, for further peculiarities of teeth and bones.