HORSES

HORSES have played an essential role in the life, and therefore in the religion, of all the peoples who have had direct contact with them, particularly the Indo-Europeans, the ancient Mesopotamians and Egyptians, the Arabs, the Chinese, and the North American Indians. It is fair to say that horses have always captured the mythic imagination through their ability to symbolize a number of related phenomena: power, wealth, divinity, sexuality, flying, and the tension between taming and freedom.

Among the earliest evidence of the importance of the horse to human culture are the magnificent wall paintings in the caves of Lascaux, in southern France, dating from around 30,000 bce. There the grouping of horses with other wild animals such as stags and bison suggests that they were probably animals that were hunted rather than harnessed or ridden. Even so, it has been proposed that certain structures depicted on the walls at Lascaux represent corrals, implying that some sort of taming may already have begun. André Leroi-Gourhan has argued that the horse is part of the male half of a general sexual bipartition in the animal symbolism at Lascaux. If this is so, there is very early evidence indeed of the horse in association with both taming and sexuality, perhaps even with the combined concept of the taming of sexuality, which is a dominant theme in the Indo-European religious symbolism of the horse.

But the true history of the horse in human religious conceptualization must begin with the first certain evidence of its domestication: the use of the chariot, which, for several centuries before horses were ridden, was employed as a means of transport, of farming, and as an instrument of war. Starting before 2000 bce from a location somewhere in the area of the Caspian and Mediterranean seas, the use of the horse to pull a chariot spread eastward through Persia to India, then south through Syria to Egypt, then west through Anatolia to Greece, and then northwest into eastern Europe. Among the Hittites, a Mittannian named Kikkulis, who was employed as Master of the Horse by the Hittite king Sepululiumas, composed the earliest known book that deals with nothing but horses, about 1360 bce. And the earliest known Egyptian figure of a horse appears on a bronze axhead of the eighteenth dynasty (c. 1450 bce), which shows a horse led in hand in a manner assumed to be that of a charioteer rather than that of a rider. Horse chariots were also found in the tomb of Tutankhamen and are depicted on a wall painting from Thebes dated about 1400 bce.

A particularly vivid description of the Egyptian chariots, and one that places horse and horseman in a religious narrative context, is the fifteenth chapter of Exodus in the Hebrew scriptures, a chapter that some scholars have dated as early as the twelfth century bce. The passage that celebrates the parting of the Red Sea and the subsequent drowning of Pharaoh's men, horses, and chariots begins "I will sing unto the Lord, for he hath triumphed gloriously; the horse and his rider hath he thrown into the sea." The term rider may not necessarily refer to a mounted horseman; it is a generic term that could apply as well to a charioteer. But it is worth noting that the horse is here associated with several themes that occur often in the mythology of the horse: armies, evil, death, and, most striking, the bottom of the ocean.

Ancient Indo-European Horse Sacrifices

With the Greeks and the Vedic Indians, and later with the Romans, the horse truly came into its own as a religious symbol, one that pervades both myth and ritual. Rituals involving horses, more particularly rituals that involve the killing of a white stallion, are attested throughout the Indo-European world. Among the ancient Norse, a white horse symbolizing the sun and accompanied by women was killed in a ritual that included obscene references to the phallus of the horse, ritual castration, and an intoxicating drink. In the Roman festival of the October Equus, a horse dedicated to Mars was killed in the course of a ritual, and a chariot race took place; in the Roman Parilia, a horse was mutilated (perhaps castrated). Among the Greeks, white horses were sacrificed to Poseidon and to the sun; a white mare was sacrificed at the grave of a maiden who had been raped and had committed suicide; black horses were inauspicious. Both Roman and Greek sources indicate a fertility cult associated with the horse, one that often agrees in striking detail with the Vedic cult of the horse. The Persians tell of a battle between an evil black horse and a good white horse, whose victory released the fertilizing rains; and the Iranians regarded white horses as symbolic of the sun (Pausanias, 3.4.20; Xenophon, Cyropaedia 8.3.11). Among the Indo-Europeans in general, it appears, the white horse was sacred.

This article shall examine the Indian and Irish models of these rituals in greater detail, but in this introductory survey it is useful to note a linguistic link between these far-flung Indo-European cults of the horse. The Gallic proper name Epomeduos may be cognate with the Sanskrit a śvamedha; both royal names are possessive compounds designating kings who have (performed) horse sacrifices. The first element of the compound simply means "horse"; the second element is more difficult to pin down, but it has the connotations of a ritual drink (such as mead) or an intoxicating drink. Thus the term as a whole may mean "intoxication with the horse"; Jaan Puhvel, who has noted these linguistic implications, remarks that "the early Indo-Europeans were undoubtedly 'crazy about horses,' and so were the Gauls" (Puhvel, 1955). It may, however, mean "one who has performed a ritual involving a horse and a sacred drink" or even—as is supported by the evidence provided by the Indian and Irish horse sacrifices—a ritual in which the horse itself supplied the substance or the sacrificial food and drink for the king, a ceremony in which a horse was ritually eaten. Whether eaten or not, horses were sacrificed by the Greeks (Herodotus, 7.113; Ovid, Fasti 1.385), by the Armenians and Massagetes (Xenophon, Anabasis 4.5; Herodotus, 1.216), and by the Scythians, of whose spectacular royal burials Herodotos provides a hair-raising description (4.71–72).

Still, it is the Vedic, Roman, and Irish horse sacrifices that provide the triangle on which the Indo-European evidence rests, however shakily. The facts of congruence in existing sources are impressive, although the weight and substance of documentation are grotesquely dissimilar. The Vedic ceremony is by far the best documented, both in terms of the contemporaneous nature of the ritual and the text describing it (both dating from 900 bce but referring to the hymns to the horse in the Ṛgveda, perhaps as much as three hundred years earlier) and in terms of the volume of data: hundreds and hundreds of pages of Sanskrit texts. The Roman ritual is a poor second, cursorily described by Polybius (12.4b), Plutarch (Quaestiones Romanae 97), and Festus (ed. Lindsay, pp. 178.5ff.) with distressing discrepancies and lacunae. The Irish ritual is even more problematic, having been described only in the twelfth century ce by a Christian monk who could scarcely believe his eyes, so appalled was he by the obscenity of the rite (Giraldus Cambrensis, Topographia Hibernica, ed. Brewer, p. 169).

Yet the parallels are truly striking. In India, a ritually consecrated stallion was killed after a chariot race; the chief queen than pantomimed copulation with the stallion, to the accompaniment of verses (spoken by priests) regarded as obscene even by the contemporaneous texts (which prescribe a "perfumed" verse to be recited at the end, to wash out the mouths of the participants). In Rome, after a race the right-hand horse of the winning chariot was sacrificed to Mars; its tail was carried to the Regia, where its blood was sprinkled on the altar (Plutarch) or the hearthstone (Festus). Men from the Sacra Via and the Suburra did battle for the head, the latter (if they won it) carrying it to the Turris Mamilia, the former to the wall of the Regia. In Ireland, the king pantomimed (or performed) copulation with a live mare who was afterward dismembered and cooked; the king bathed in her broth and drank it, and the broth was then distributed to the people.

The common thread in all three rituals is the killing of an equine. In two of the rituals (India and Rome) the horse is a stallion; in two of the rituals (India and Ireland) there is a sexual union as well as a death. It could be argued, from the writings of Georges Dumézil and others, that the ritual emphasizes a different one of the three Indo-European functions in each of the three cultures in which it appears: the Roman primarily martial, the Indian royal and sacred, the Irish fertile and nourishing. But all three rituals can and do incorporate all three levels of symbolism. A ceremony that is about royalty and the power of the king not only can but, in a sense, must also be about sexuality and nourishment: for the ancient Indo-European stallion symbolized at once the powers of the warrior; of the king, and of the virile male.

Ancient Indo-European Horse Myths

Given the primacy of the stallion in the aggressively virile cultures of the Indo-Europeans, how is one to explain ritual focus on the Irish mare? It could be argued that the Irish variant is properly Gallic, rather than Indo-European, and make the case (as Robert Graves did in The White Goddess, 1948) for an ancient Gallic horse goddess whose cult was superseded by that of an Indo-European horse god. In support of this contention is the Gallic cult of the goddess Epona, almost the only goddess worshiped in the same guise by both continental and insular Celts. Intimately connected with the Welsh Rhiannon and the Irish Macha, whom shall soon be encountered, and thematically connected with the horseheaded Greek Demeter, Epona is often depicted as a woman riding on a mare, or as a mare, or with a mare's head; she is also associated with a male horse god, Rudiobus. Epona, whose name comes from the Proto-Indo-European *ékwos, "horse" (Lat., equus; Skt., aśva ), is particularly concerned with pregnant mares and with foals. Pseudo-Plutarch (parallel 29; cited by Le Roux, 1963, p. 133) gives what may be the only ancient record of a Celtic hierogamy like the one that is described, as a ritual, by Giraldus Cambrensis so many years later: "A certain Phoulouios Stellos, who hated women, had intercourse with a mare. In time, she brought forth a beautiful maiden whom she named Epona, a goddess of horses."

Celtic mythology offers rich support for the concept of an ancient horse goddess. The Irish Táin Bó Cuailnge narrates the myth of Macha, a tri-functional equine goddess who, forced to run in a chariot race while she is pregnant, dies bringing forth twins or who, in another avatar, brings forth a son at the very moment when a mare in the stable gives birth to twin foals (Kinsella, 1970; Gricourt, 1954). And the Welsh Mabinogi tells the story of Rhiannon, who appears to King Pwyll riding on a white horse, marries him, and bears him a child while a mare has a foal at the same moment; accused (falsely) of killing the child, Rhiannon is condemned to carry guests from the mounting block to the court on her back.

The myth of the mare goddess has a broader Indo-European distribution as well. In India, the myth begins with references in the Ṛgveda to the wife and false-wife of the sun, a myth that is told in greater detail in the Brāhmaṇas and the Purāṇas: Vivasvant, the sun, married Saraṇyū, who fled from him and substituted for herself another female, Chāyā ("dark shadow") upon whom Vivasvant begat a son, Manu, the ancestor of the human race. Meanwhile, Saraṇyū took the form of a mare and fled from Vivasvant, but he took the form of a stallion, followed her, and covered her; upon giving birth to the twin horse-gods, the Aśvins, she abandoned them. The parallels with Celtic myths are striking: A goddess in the form of a white mare takes human form and mates with an aging sun king; impregnated by him, she gives birth to hippomorphic twins, the ancestors of the human race, whom she injures or abandons, and she leaves the king to return to her heavenly home. The inversions and reversals that take place over the wide Indo-European area and through the centuries are complex, but clearly this is some sort of protean mythic core.

Greek mythology supplies further evidence in support of this corpus. Demeter, who is often depicted with a mare's head, mated with Poseidon (the god of the sea, to whom horses were sacrificed, and who was himself called Hippios, "equine"; Apollodorus, 3.6.8; Pausanias, 8.25 and 8.42); in Arcadia, Demeter is portrayed as Black Demeter, with the head and mane of a horse on the body of a woman (Ovid, Metamorphoses 6.406b). Poseidon is also involved in several myths in which a woman is raped by a god in the form of a stallion and gives birth to foals that she attempts to destroy; he is more distantly involved in a Greek cycle of myths about overprotective fathers of equine goddesses who destroy their suitors (the myths of Hippodameia, Hippomenes, and Alcippe). Glaucus and Diomedes of Thrace are said to have had savage mares, made more savage by their enforced chastity, who devoured men, and Hippolytus (well known from Euripides' tragedy), who worshiped Artemis and denied Aphrodite, was dragged to death by chariot horses that were frightened by a monster sent by Poseidon from the sea.

European Myths of Evil Mares

The pattern of myths of evil mares is almost exclusively Indo-European, which is hardly surprising, given the special place of the horse in Indo-European culture. The negative symbolism of the Indo-European mare is epitomized by the myth, widely documented in India, in which a demonic female full of anger and destructive lust is tricked into taking the form of a mare with flames shooting out of her mouth. While she dwells at the bottom of the ocean, the flames in her mouth keep the ocean from overflowing its bounds and the ocean keeps her flames from destroying the world. On doomsday she will emerge from the ocean; her flames will destroy the universe with fire; and the uncontrolled waters of the ocean will flood the world. The underwater mare is thus a symbol of the tension between uncontrolled powers and the dangers that arise from the brutal suppression of those powers; it is a symbol of the paradox of the wild and the tame, in all three Indo-European spheres: the sacred, the martial, and the sexual.

The underwater mare appears, in various transformations, throughout later European mythology. Celtic mythology describes aquatic monsters known as Goborchinn ("horseheads") as well as horse eels and water horses, the forerunners of sea serpents and dragons like the Loch Ness monster, whose heads are often surprisingly equine. And, closer to home, one can see this symbolism at the heart of the climactic scene in Richard Wagner's opera Götterdämmerung (The twilight [or doomsday] of the gods). Brünnhilde is one of the Valkyries, the female warrior spirits who ride their winged horses through the skies to bring fallen warriors to Valhalla; at the end of the opera, Brünnhilde mounts her white horse and rides through a wall of fire to her death, whereupon the waters of the Rhine rise and flood the world.

In folklore, the more anthropomorphic aspects of the myth, particularly the implications of the relationships between the mare and her children, are stressed. The Antti Aarne-Stith Thompson index of tale types and motifs gives many examples of myths in which a queen is falsely accused of the murder of her children and condemned to death, myths in which horses usually play a part. The accused woman sets out on a mare, and the wicked fairy who calumniates her is torn to pieces by a horse (TT 451); the unfaithful wife is transformed into a mare, like adulteresses in the Arabian Nights as well as in Finnish, Russian, and Italian tales (TT 449). Witches are closely associated with mares: A witch may be accompanied by a horse, she may appear as a horse, she may transform a man into a horse and ride him, or she may become a man-eating mare. The equine witch appears consistently as the villain in Indo-European folklore: She is the female fiend who eats children and rides her victims (an image with psychological overtones of fear and sexuality); she is the black maiden from hell, riding on her white horse; or she is the leader of the wild chase of witches on their phallic broomsticks, the horses of death. The image of the erotic woman on the white horse is not necessarily negative—there is always Lady Godiva, not to mention naked women on horseback in contemporary soft-core pornography—but her very eroticism is a negative value in the ancient Indo-European conceptual system, in which women should be not erotic but chaste.

The term nightmare, even though it is etymologically unrelated to the word for the female horse, comes to assume explicit equine overtones from an early period in European mythology, in part through the attraction of assonance and in part through the influence of an already developed mythology. The true etymology is from the Old English mare ("hag"), and a nightmare, according to the Shorter Oxford English Dictionary, is a "female monster … supposed to settle upon people and animals in their sleep, producing a feeling of suffocation." The prototype of the nightmare who presses down on the sleeper or has intercourse with him while lying on top of him is the mare who rides perversely astride her husband or victim. In modern reinterpretations of the image of the nightmare, in literature and art (the horse in Fuseli's haunting painting entitled The Nightmare, or in Blake's Death on a Pale Horse, or the tortured horses in Picasso's Guernica), the cluster of meanings related to the several homonyms often merge: mother (Fr., mère ), female horse (Eng., mare ), ocean (Lat., mare; Fr., mer ), death (IE, *mer, *mor ), and the underlying Old English etymological meaning, "hag."

One can postulate chronological levels in the history of the degradation of the symbolism of the mare. At first there may have been one mare goddess, an awesome, dangerous, sacred creature (sacred in Rudolf Otto's sense of the word: mysterium fascinans et tremendum ), who was sought by the king, captured, and wooed. She is a source of power, who invigorates the aging king by her annual ritual copulation with him; she dies in a sacrifice of her immortality to his mortality. At this period, the mare is simultaneously maternal, sororal, and erotic. In Semitic and Babylonian myths, she is manifest in the figures of Inanna and Ishtar, both of whom were said to copulate with horses. But in later European mythology, the mare goddess was split into two parts, the good mother and the evil whore, and the benevolent white mare is given a malevolent, black alter ego.

This transition is even more sharply marked in the closely related mythology of the swan-maiden. Mares in many Indo-European myths about evil women are closely associated with birds: They assume the form of birds or appear as winged horses. In the swan-maiden variants of the theme, a woman from the other world assumes the more delicate and feminine form of a white bird, instead of a white horse; she lives with a prince for a while and then leaves him when he violates the condition that she had set for their cohabitation (not to ask her name, or not to see her naked). This may be a very old Indo-European motif indeed, judging from archaeological evidence from Europe before 3500 bce depicting the bird goddess. Her mythology begins with the Vedic myth of Pururavas and Urvasi and extends to the ballet figures of The Firebird (the firebird is the Russian version of the magic sunbird) and Swan Lake, in which Odette, the good, chaste White Swan, is opposed by Odile, the evil, seductive Black Swan. Then, too, when the Valkyries are not riding horses they become swans.

But the demotion from mare to swan was not the last step in the degradation of the symbol. The swan became male. In Greek myth, Zeus assumes the form of a white swan in order to seduce Leda as she is bathing in a river (Leda's two sons, Castor and Pollux, became known as the Dioscuri, or equine twins, the Greek parallel to the Vedic Asvins). And in the legend of Lohengrin, it is he, not she, who rides in the swan boat. In Lohengrin's story the more ancient myth of the immortal woman who visits the mortal man or king came to be replaced by the myth of the immortal man who rescues the mortal woman. In a skiff drawn by a white swan (here a male), Lohengrin rides, as on a white horse, to the rescue of Elsa; the helpless female awaits the great horse/swan god who deigns to visit her and who will make her promise never to ask him his name or his lineage. Now Leda awaits Zeus, awaits the moment when she may, in Yeats's words, "put on his knowledge with his power / before the indifferent beak could let her drop."

The Rider on the White Horse

Thus the white stallion came to supplant the white mare in Indo-European mythology at a very early period. His mythology, like hers, was a mythology of ambivalence, of the coincidence of opposites, but the powers in question were different. The stallion came to symbolize not only death (as had the mare) but also rebirth, not only the taming of the wild (as had she) but also complete freedom from all social bonds.

Plato likened the human soul to a charioteer who had harnessed two horses to his chariot, one pulling him toward brutish sensuality, the other to a higher spiritualism; and, before Plato, the Indian Upanisads had likened the senses to horses that must be controlled if they are not to remain vicious and wild. The locus of this taming is the mouth of the horse, whence are derived such metaphors as "to bridle," "to curb," "to take the bit between the teeth," and so forth. The horse's mouth was therefore seen as the point of dangerous interaction. This notion is a misconception (for, as every horseman knows, although horses can indeed bite, it is the other end of the horse that poses the real danger, and horses are in any case strict vegetarians); nevertheless, it is the source of the many myths in which horses devour people, myths in which doomsday flames come out of the horse's mouth (or nostrils). That the mouth of the mare is believed to be dangerous is an instance of the projection of aggression, assuming that she will injure you with the organ where you have injured her (through the bit).

In Christian mythology, doomsday appears as the four horsemen of the apocalypse, or the rider on the white horse; in India, death becomes incarnate as the centaur or white horse named Kalki, an avatar of Viṣṇu who will usher in the final Kali Age and the end of the world. This is the image captured in Peter Schaffer's play Equus, in which an adolescent boy confuses together in his fantasies the tortured mouth of the horse-god that he rides naked in sexual ecstasy and the tortured head of Christ bridled in his crown of thorns. And it is the image that begins James Joyce's famous poem:

I hear an army charging upon the land
And the thunder of horses plunging, foam about their knees.

Arrogant, in black armour, behind them stand,
Disdaining the reins, with fluttering whips, the charioteers. (from Chamber Music, 1907)

But the other, positive aspect of the horse never lost its symbolic power. Centuries before the Roman invasions, someone carved into the chalky hillsides of the English Downs several colossal images of a white horse. The horse by itself, unharnessed, unbridled, unridden, was always at home in the mountains, close to its divine home and far away from the ropes of humans. The horse thus remained always a symbol of freedom. In the ancient Indian horse sacrifice, the stallion wandered freely for a year before the ceremony, attended by his herds and followed by the king's men, to claim for the king whatever grazing land he cared to wander through. This image of freedom was somehow preserved rather than canceled by the later composite image of the white horse and its noble rider, who were thought of as a single creature, ideally a kind of centaur. The horse transferred its freedom and nobility to its rider, even as the ancient Indian stallion transferred these qualities to the king during the sacrifice. Thus Saint George, always mounted on a white horse, kills the very dragon that is, as has been seen, a variant of the demonic underwater mare, the shadow side of the white stallion itself; and medieval equestrian imagery placed not only knights and kings but princes of the church on horseback, to symbolize all that was not only noble, but divine.

The horse carried humanity from earth to heaven. In India and Greece, as well as in medieval Europe, one reads of princes who are lured by white stags (or white swans, or white horses, or unicorns) from the safe territory of the royal parks to the thick of the forest, to the Other World, where they may meet their princess or encounter their dragon (or both, or both in one). The many tales of winged horses, as well as the conflation of horse and bird, often transform this horizontal voyage into a vertical flight. Not until the advent of photography in the mid-nineteenth century did people come to realize that a galloping horse did not actually fly, with forelegs stretched forward and hindlegs backward, and even then galloping continued to feel like flying. In many of the shamasitic myths of Inner Asia, China, and India, the initiate mounts a white horse and is suddenly carried off, out of control, into the world of the gods, where the initiation takes place. Thus the horse leads humankind from the world of the tame to the world of the wild, the magic, supernatural world of the gods.

This symbolism found its expression in the mythology of the American West, where the magnificent white mustang who can never be caught stands on the mountains with the wind lifting his mane, symbolizing all that is wild and free. Yet the stallion is caught, to become the alter ego (in India one would say the vehicle, or vahana ) of the cowboy, who comes himself to represent the last bastion of male freedom—freedom from sexuality (the cowboy rides alone, like Lancelot, whose chastity was his power), from the law (for even the lawmen tend to be mavericks, and the outlaws are good outlaws), but most of all from being tamed or "fenced in."

Humankind can never entirely succeed in taming the horse. This is the charm and the challenge of any intimate association with a wild animal, that it retains some measure of its wildness. But the horse untames humans, transferring to them—or, one might say, sacrificing for them—some of its own wildness and freedom.

Bibliography

A good overview of the history of the horse in human culture is provided by Anthony Austen Dent's The Horse through Fifty Centuries of Civilization (New York, 1974). Much of the material on the myths and rituals of the horse in India, Greece, and Ireland that I have used in the article above has been condensed from pages 149–282 of my Women, Androgynes, and Other Mythical Beasts (Chicago, 1980), which, in turn, draws upon several basic studies of indo-European equine symbolism (in addition to the primary texts reproduced and analyzed therein): the writings of Georges Dumézil, particularly "Derniers soubresauts du Cheval d'Octobre," in his Fêtes romaines d'été et d'automne (Paris, 1975), pp. 111–168, 177–219. Paul Émile Dumont's L'asvamedha (Paris, 1927); Jean Gricourt's "Epona-Rhiannon-Macha," Ogam 6 (1954): 22–188; Wilhelm Koppers's "Pferdeopfer und Pferdekult der Indogermanen," Wiener Beiträge zur Kulturgeschichte und Linguistik 4 (1936): 279–411; Françoise Le Roux's "Recherces sur les éléments rituels de l'élection royale irlandaise et celtique," Ogam 15 (1963): 123–137; and two articles by Jaan Puhvel, "Vedic asvamedha and Gaulish IIPOMIIDVOS," Language 31 (1955): 353–354, and "Aspects of Equine Functionality," in Myth and Law among the Indo-Europeans, edited by Jaan Puhvel (Berkeley, 1970). For prehistoric images of the horse, see André Leroi-Gourhan's article "Préhistoire," in Dictionnaire des mythologies, edited by Yves Bonnefoy (Paris, 1981); for horses in Britain, see Anthony Austen Dent and Daphne Machin Goodall's The Foals of Epona (London, 1965); and for the Irish Táin, Thomas Kinsella's translation, The Tain, Translated from the Irish Epic "Tain Bo Cuailnge" (Oxford, 1970).

New Sources

Hausman, Gerald. The Mythology of Horses: Horse Legend and Lore Throughout the Ages. New York, 2003.

Wendy Doniger (1987)

Revised Bibliography

Horses

Resources

Horses are members of the family Equidae, which includes the wild asses of Africa and Asia and the zebras of African plains and mountains. The origins of horse-like mammals have been traced back some 55 million years to a small “dawn horse” known as Eohippus. More recently, during the Pliocene and Miocene periods (which ended some 1.5-2 million years ago) horses and their relatives as we know them today were probably the most abundant medium-sized grazing animals in the world. Since then, every species has experienced a major reduction in population size.

One wild horse, the tarpan, a small, shy, gray species lived on the Russian steppes of Eurasia until some time in the eighteenth century, when it became extinct because of overhunting and cross-breeding with domesticated species. Almost nothing is known about this animal apart from scant information in a few museums. The only other true wild horse, the slightly larger Przewalski’s horse (Equus przewalskii ), is now also thought to have gone extinct in the wild as recently as the mid 1960s. Some members of this species were, however, preserved in captivity so at least some representatives of this ancient lineage remain.

Horses are grazing animals of wide open plains, where constant vigilance is necessary in order to avoid predators such as lions, tigers, leopards, and wild canids. Apart from their keen senses of vision, hearing, and smell, horses are well equipped to outrun most potential attackers. Wild horses also undergo extensive seasonal migrations in search of optimal feeding and watering habitat. The feet of these hoofed animals (perissodactyls) are modified for agility and rapid movement. Horses have light feet with just one toe and, when moving, the hoof is the only part of the foot to touch the ground. Horses are also characterized by their long, slender legs, capable of a steady,

prolonged movement or a long, striding gait. A deep chest allows for their large lungs, as well as the animal’s large stomach, which is important for digesting the great amounts of relatively bulky plant materials.

Grasses and herbs form a major part of the diet. While these materials are relatively abundant, they are often not very nutritious, being low in protein and difficult to digest. Horses eat large quantities of plant materials each day and must be able to transform this into energy and nutrition. Plant cells are composed of cellulose, which the digestive system of few mammals is capable of breaking down. To assist with this process horses and their relatives rely on microorganisms within the large intestine and colon to break down and ferment their bulky diet. In contrast to ruminating animals such as deer and cattle, horses have a small and relatively simple stomach in which proteins are digested and absorbed. The digestive system of horses is far less efficient than that of a cow, for example, which means that the former must eat considerably more of the same materials in order to acquire a similar amount of energy.

Przewalski’s horse is closely related to the domestic species (Equus caballus ), but is distinct in its appearance. Reaching more than 7 ft (2 m) at the shoulder, and with a length of almost 8 ft (2.5 m), these horses are a dark bay-dun color with a much lighter underside and muzzle patch. The dark mane narrows to a single, narrow dorsal stripe along the back, ending in a black tail. Early Stone Age cave paintings feature many illustrations of horses that closely resemble this species. It was formerly widespread in steppe and semiarid habitats of Kazakhstan, Sinkiang, Mongolia, and parts of southern Siberia. The Przewalski’s horse first became known to Western science in 1879, when it was discovered by a Polish explorer after whom the horse is named. Although there are no known estimates of the initial population size, by the early twentieth century it was already rare and found only in parts of southern China and Mongolia.

These animals were once highly prized by Mongolian people for their stamina. The wild herds once also provided semi-nomadic tribes with an essential supply of milk, meat, and hides, the latter being used for clothing as well as construction materials for their hut-like homes. Although the species is now extinct in its native habitat, sufficient animals are kept in zoological collections to enable a systematic program of captive breeding to take place. As a result of these efforts, there are now more than 1,500 individuals in captivity in many parts of the world. Apart from the hopes of conservationists to see this horse returned to its natural habitat, there is also a strong national desire amongst people in Mongolia to see these animals returned to the plains of its rightful heritage.

In their natural habitat, wild horses live in herds that consist of a number of mares, a single stallion, and foals and colts of a wide age span. The stallion is responsible for leading the herd to safe watering and feeding grounds and for protecting the females and young from predators. Stallions are extremely protective of their herds, and fights with other males who attempt to overthrow the stallion are common. Male horses fight with their hooves and teeth, especially the enlarged canines of the lower jaw—a prominent feature on mature males. A wide range of facial and other expressions are used to help avoid conflicts or to ensure that these are of short duration, as animals risk injury in such sparring events. Baring the teeth and curling the lips, while at the same time flattening the ears, is one of the most aggressive threats, while a number of vocalizations and stomping movements with the feet are also used to enhance the meaning of the gestures.

Almost everything we know about the social life of these animals is based on observations of semi-wild Przewalski’s horses and feral populations of domestic horses. In the Przewalski’s horse, young are born from April to June, following a gestation period of about 330 days. Mares usually bear a single foal which, shortly after birth, is able to stand up and follow its mother—an essential ability if the foal is not to fall prey to ever-vigilant predators. Foals remain close to their mothers for the first few weeks of life and do not become independent until they are almost two years old. Following this, they remain with the herd for several more years until they mature. In a natural situation, males are driven away from the herd as they reach sexual maturity. These solitary males usually join with other males to form small bachelor herds. Females, in contrast, may remain with the herd they were born into and will, in time, breed with the dominant male of the herd.

The precise origins of the domestic horse are not known but they likely arose from either the tarpan or Przewalski’s horse. The earliest records of domestication are unclear and it is possible that this took place simultaneously in different parts of the world. Some reports suggest that it was attempted as early as 4000 BC in Mesopotamia and China, while evidence suggests that by 2000 BC domesticated horses were in use in China. Since then, horses have been bred for a number of purposes and there are now thought to be more than 180 different breeds. The powerful Shire horses were bred as draught animals in England, while most modern thoroughbreds, bred for their speed, stamina, and grace, are derived from breeding other species with primarily Arabian horses. The increasing spread of agriculture almost certainly played an important role in the use of domesticated species for draught purposes, but others were also bred and crossbred for their hardiness in extreme climates. Horses have also featured heavily in warfare, and many battles have been won and empires taken by mounted warriors.

Wild horses have suffered considerably since the arrival of humans on Earth. Horses and asses were once widely harvested for their meat and skins, particularly in parts of Asia. Elsewhere, the integrity of true wild species became diluted as domestic species interbred with wild animals. Natural changes may also have had some role to play in the demise of the wild horse, but it is more likely that human encroachment on the great plains of Asia, with spreading agriculture, has had the greatest and most long-term effect.

It is now too late to protect the last true wild horses, but considerable efforts are required to ensure that the last member of this ancient lineage, Przewalski’s horse, and its natural habitat are protected in a manner that would enable this species to be reintroduced to its native habitat. Consideration should also be given to the preservation of wild stocks of domesticated varieties, such as the mustangs of North America, the Dartmoor and Exmoor ponies of Great Britain, and the brumbies of Australia, where these species have a role to play in maintaining the ecology of their respective habitats. In some countries, however, feral horses have caused considerable destruction to local plants and control programs are required to limit herd size so that they do not cause irreversible damage to fragile ecosystems. In other regions, feral horses play a useful role in cropping long coarse grasses, which helps keep the ecosystem open for other smaller, more fastidious grazing animals and plants. Some plants are known to germinate only when their seeds have passed through a horse’s digestive system, as many of these plants may have evolved at a time when large herds of wild horses roamed the plains and acted as natural seed dispersers.

See also Livestock.

Resources

BOOKS

Knight, Linsay. The Sierra Club Book of Great Mammals. San Francisco: Sierra Club Books for Children, 1992.

Moehlman, P.D., ed. Equids: Zebras, Asses and Horses. Status Survey and Conservation Action Plan. Gland, Switzerland: IUCN, 2002.

Nowak, Ronald M. Walker’s Mammals of the World. 6th ed. Baltimore: The Johns Hopkins University Press, 1999.

Stidworthy, John. Mammals: The Large Plant-Eaters. Encyclopedia of the Animal World. New York: Facts On File, 1988.

Wilson, D.E., and D. Reeder. Mammal Species of the World. 3rd ed. Baltimore: Johns Hopkins University Press, 2005.

OTHER

IUCN/SSC Equid Specialist Group. “Species Profiles.” <http://www.iucn.org/themes/ssc/sgs/equid/Spp.html> (accessed October 5, 2006).

HORSE

HORSE. The horse in America dates at least from the single-hoofed Equus caballus that emerged in Pleistocene times, about 1 million years ago. Ancestors of the modern horse began a westward migration from North America across the land bridge between the north coast of Alaska and that of Siberia. Some paleontologists suspect that the horse disappeared in America not more than, and possibly less than, 10,000 years ago.

The horse was reintroduced into the Western Hemisphere with the voyages of discovery by Christopher Columbus for Spain at the end of the fifteenth century. These Spanish steeds, derived from Moorish stock, first landed in the Caribbean in November 1493. The Spanish horses acclimated rapidly and within twenty years formed the chief supply for the Spanish mainland expeditions. Other European explorers brought horses to eastern and western parts of the New World in the sixteenth and seventeenth centuries. English colonists imported European horses. In the British colonies as a whole, horses were valued for riding, hunting, and racing.

The adoption of the horse by Native Americans, after the initial impact, increased rapidly and proved a major implement of change for the nomadic Plains tribes. By 1660, Indians had learned the value of horses and had begun to use them. During the next forty years the horse spread into the plains and mountains with great rapidity. In 1805 and 1806 Meriwether Lewis and William Clark noted the use of horses by Indians. With horses, the Kiowa ranged more than 1,000 miles in a summer. Some eastern forest tribes, once partially agricultural, moved out into the grassland with acquired horses and turned to hunting. The equestrian tribes were often at war with one another and raided white settlements to steal more horses.

Horses were crucial for transportation and inland migration prior to the development of the railroad. Extractive industries, manufacturers, and city distributive systems were all dependent on horsepower. The stagecoach was the first inland interregional utility, and the post rider opened communication with outlying settlements. Horses drew canal boats and railcars and served hunters, trappers, and miners. Cow horses carried cowboys on long cattle drives, herding livestock. The night horse was used to stand guard. Cavalry mounts and supply teams were adjuncts of military organizations and campaigning on every front. Approximately 1,500,000 horses and mules died during the Civil War (1861–1865).

The twentieth-century revolution worked by the internal combustion engine resulted in a displacement of horses for power and transportation. Tractor-drawn corn planters could plant an average of seventy acres of corn, compared to a horse-drawn average of only sixteen acres. From about 26 million farm horses and mules in the United States in 1920, the number declined to slightly more than 3 million horses and mules on farms in 1960.

American Breeds

American horse breeders carefully selected breeding stock and monitored pedigrees in an attempt to cultivate desired characteristics. Sometimes especially swift or capable horses were produced by chance. Superb horses were occasionally discovered and of unknown parentage. These animals were retained as studs or broodmares in the hopes that their talents or physical attributes would be transmitted to offspring. As a result, breeds unique to the United States were developed, especially in the twentieth century, to meet performance needs. Breed associations were formed to preserve genetic records and promote specific types of horses.

The American Quarter Horse is the first horse breed distinctive to the United States. Descended from a mixture of American breeds and imported bloodstock during the colonial period, Quarter Horses are exceptionally sturdy, muscular, versatile, and fast. They accompanied Americans from Atlantic colonies to the western frontier, where they were valued for their cow sense. Cattlemen, including those at the famous King Ranch in Kingsville, Texas, developed outstanding lines of Quarter Horses. One of the King Ranch Quarter Horses, Wimpy, was named grand champion stallion at the 1941 Fort Worth Exposition. The American Quarter Horse Association, founded in 1940, assigned Wimpy its first registration number, and he became a leading foundation sire. Quarter Horses fill many roles. The All-American Futurity at Ruidoso Downs, New Mexico, distributes a $2 million purse to Quarter Horses that sprint 440 yards. The American Quarter Horse Heritage Center and Museum at Amarillo, Texas, preserves this breed's history.

Justin Morgan's horse Figure, foaled in Massachusetts in 1793, founded a line notable not only for speed but also for light draft. Rhode Island developed one of the most distinctive and noted types of the period in the Narragansett pacer, a fast, easy-gaited saddle horse, but one not suited for driving or draft purposes. The stylishly moving American Saddlebred represents a mixture of Narragansett Pacer, Arabian, Standardbred, and Thoroughbred ancestors. Established in 1891, The American Saddle Horse Breeder's Association (later renamed American Saddlebred Horse Association) was the first American breed association, and Denmark was designated the main foundation sire.

Tennessee Walking Horses represent a conglomeration of breeds which produced a gaited horse that is renowned for its running walk. This breed is based on the line of foundation sire Allan F-1. The Racking Horse has a comfortable, natural four-beat gait which southern planters valued. Ozark settlers bred the Missouri Fox Trotter, which had a sliding gait that eased travel in hilly areas.

Most modern Appaloosas are related to the horses bred by the Nez Perce Indians. These spotted horses often

also have Quarter Horse, Thoroughbred, and Arabian ancestry. Joker B. and Colida were two of the Appaloosa Horse Club's outstanding foundation stallions after that association was formed in 1938. The Pony of the Americas (POA) was created by crossing an Appaloosa mare and a Shetland pony stallion. The resulting foal, Black Hand, became the POA foundation sire, establishing a breed especially for children to ride and show.

The American Cream Draft Horse is the sole draft breed created in the United States. Representatives of this breed are descended from a pink-skinned, cream-colored Iowa mare named Old Granny. After mechanization resulted in the slaughter of many draft horses, the American Minor Breeds Conservancy cited the American Cream Draft Horse as an endangered breed.

Horse Culture

By the beginning of the twenty-first century, 6.9 million horses were living in the United States and were used by 1.9 million horse owners for recreational or commercial purposes. Approximately one-half of American horses are kept for their owners to enjoy and ride for pleasure. About one-third of horses are used primarily for shows and competitions. An estimated 725,000 horses race or are used as broodmares and studs on racehorse farms. Slightly more than one million horses fill working roles such as agricultural laborers and police mounts. Others are used as rodeo stock or for polo teams.

Although horses are found throughout the United States, Kentucky's Bluegrass region is specifically identified with equines. The center of American horse racing activity, Kentucky is home to major racing stables and tracks. The Kentucky Horse Park and the International Museum of the Horse were established at Lexington, Kentucky, in 1978 to educate people about horses and to host significant equine-related artistic, cultural, and sporting events. This thousand-acre site includes the Hall of Champions and the grave of the famous racehorse Man o' War. The museum is the world's largest equestrian museum and examines the history of human-horse interactions, providing online access to exhibits via the Internet. The daily Parade of Breeds highlights representatives of distinctive American horse breeds.

Pony, 4-H, and local riding clubs offer opportunities for equestrians to learn about horses. Riders barrel race at rodeos. Equestrians also compete at such prestigious events as the National Horse Show, held annually at Madison Square Garden in New York since 1883. Members of the United States Equestrian Team participate in international equestrian sporting events including the Olympics.

Legislation and Statistics

The American Society for the Prevention of Cruelty to Animals was organized in 1866 to protest horse abuse. During the late nineteenth century, George T. Angell established similar humane groups in Massachusetts to protect horses. Congress passed the Horse Protection Act (HPA) in 1970, then amended it in 1976 with further revisions in 1983 to provide legal measures to prevent abusive treatment of horses. Specifically, the HPA forbids people from soring horses. This procedure involves application of stimulants, such as chemical pastes or sharp chains, to make a horse step higher or perform more spectacularly than normal in order to win competitions or earn higher prices at sales. After receiving training and being licensed by a United States Department of Agriculture (USDA)–approved horse agency, a Designated Qualified Person (DQP) monitors horses at shows and auctions to inspect, detect, and bar any animals that have been sored.

The HPA declares that soring of horses for exhibitions or sales as well as the interstate transportation of sored animals to horse shows is prohibited. People convicted of soring horses are usually prevented from participating in future shows and sales for a specific time period, occasionally being disqualified for life, fined as much as $5,000, and sometimes sentenced to as much as a two-year prison term. State and local governments often prosecute people for committing acts that violate regional animal welfare legislation.

In 1996, the American Horse Council Foundation, created in 1969, commissioned a study to evaluate how the horse industry impacts the U.S. economy. The study determined that the American horse industry contributes annually $25.3 billion of goods and services to the national economy and pays taxes totaling $1.9 billion. The horse industry provides more income to the gross domestic product than such significant industries as furniture and tobacco manufacturing, motion picture production, and railroad transportation.

Throughout the United States, breeding, training, and boarding stables, horse show arenas, racetracks, and auction barns hire workers for various tasks, ranging from grooms and stable hands to jockeys and stable managers. At least 7.1 million people participate in some aspect of the horse industry. More Americans are employed by the horse industry than work in media broadcasting, railroad, or tobacco, coal, and petroleum manufacturing positions. Millions more are active as spectators at equine events.

BIBLIOGRAPHY

American Horse Council Home page at: http://www.horsecouncil.org/

American Quarter Horse Association. Home page at http://www.aqha.com.

Appaloosa Horse Club. Home page at http://www.appaloosa.com.

Kentucky Horse Park and the International Museum of the Horse. Home page at http://www.imh.org.

Tennessee Walking Horse Breeders' and Exhibitors' Association. Home page at http://www.twhbea.com.

Cypher, John. Bob Kleberg and the King Ranch: A Worldwide Sea of Grass. Austin: University of Texas Press, 1995.

Denhardt, Robert M. The Quarter Running Horse: America's Oldest Breed. Norman: University of Oklahoma Press, 1979.

Edwards, Elwyn Hartley. The Encyclopedia of the Horse. Photography by Bob Langrish and Kit Houghton. Foreword by Sharon Ralls Lemon. London and New York: Dorling Kindersley, 1994.

Gray, Bob. Great Horses of the Past. Houston: Cordovan Corp., 1967.

Hillenbrand, Laura. Seabiscuit: An American Legend. New York: Random House, 2001.

Horse Industry Directory. Washington, D.C.: Published annually by the American Horse Council in cooperation with American Horse Publications, 1976–.

Mellin, Jeanne. The Complete Morgan Horse. Lexington, Mass.: S. Greene Press, 1986.

Ward, Kathleen Rauschl. The American Horse: From Conquistadors to the 21st Century. Belleville, Mich.: Maple Yard Publications, 1991.

Zeh, Lucy. Etched in Stone: Thoroughbred Memorials. Lexington, Ky.: Blood-Horse, 2000.

TomFulton

Elizabeth D.Schafer

See alsoHorse Racing and Showing ; Indians and the Horse ; Mule ; Mustangs ; Pony Express ; Rodeos .

Horses

One common misconception about evolution is that it occurs in a straight line, from an ancestor to a descendant. Although it is possible to trace the lineage, or history, of a certain species, the wider view shows that evolution is actually a very broad process. It may be helpful to visualize evolution as a tree from which many branches sprout, with each branch representative of a line of organisms evolving from the center of the tree. Many of these branches, or lineages, may die out. Other branches continue to grow and branch out further, resulting in the great diversity of life on Earth today. The history of the horse is an excellent example of this evolutionary "tree." Horses did not evolve in a straight line from a common ancestor, through species after species, until the modern wild horse appeared. In fact, the evolution of the horse is a story of great divergence and extinctions that continued through time, until only one species remained.

Paleontologists have discovered a very good record of horse fossils in North America, where the horse first appeared, and have learned much about its early history. Other continents have been subsequently searched for fossils, and the migration and distribution of the horse is now well-known. From the remains of a few small populations of true wild horses in Europe and possibly central Asia, thriving communities of horses now exist in most regions on Earth.

The Beginning

The ancestors of the horse were browsers who fed on the bushy and leafy types of vegetation found in forests. They ate leaves of trees and shrubs and occasionally fed on tender grasses. Scientists deduced what they ate from studying the fossil teeth of animals that had a similar bone structure to the modern horse, but that had bumpy teeth, instead of the flat, grinding teeth horses have today. These early ancestors were small animals, about the size of a fox or a medium-sized dog.

Evolutionary scientists recognize that environment often drives natural selection , and that natural selection leads to evolution. One force causing the transformation in horses was the constant alteration of climate that began about 60 million years ago and continues through the present. As the climate became hotter and drier, two important events occurred. First, the forests shrank and became patchy throughout North America. This reduced the habitat of the forest-dwelling members of the horse group. Second, different forms of grasses, called "C4 grasses," evolved. These grasses were tougher than the fragile forest grasses and better able to withstand harsh conditions. They spread throughout the more arid regions and formed vast plains. These plains created a less nutritious but more stable food source for the animals. The formation of the grasslands provided a new habitat in which many forms of animals, like the camels and horses, thrived. C4 grasses contained a high concentration of a glassy mineral called silica. The horse species that survived this new diet developed stronger, flatter, and more complex teeth than their forest relatives. Most of the evolution of horses was identified and traced by studying these changes in tooth shape and structure.

The second major factor that affected the evolution of the horse was the emergence of more effective competitors, such as the artiodactyls (herbivores like camels, deer, and bison), and swifter predators, especially the cats with their saberlike canine teeth. These swift and efficient predators found the smaller, forest-dwelling horses to be easy prey, resulting in the swift extinction of the horses. This kind of selection pressure favored the swifter and more wary equids of the open grasslands. So as one horse lineage died out, another evolved quickly. This pattern continued until the end of the Pleistocene epoch about 11,000 years ago. Only one species of horse, Equus equus, remains from this once diverse group of animals.

The Story of the Bones

All information scientists know about ancient horses has been gathered from the fossil remains of their skeletons. The skull, and the teeth it contains, can be read almost like a book, revealing how and when physical changes occurred and in what order. While no real "trends" are apparent in the overall picture of horse evolution because so many different species are involved, there were some general changes. As horses evolved, their toes were continually reduced in number until the condition of standing on one toe, like the modern horse, was achieved. The teeth became larger, with a more complex surface. The face became longer. In addition, the overall body size increased, growing from the tiny size of the forest dwellers to the significantly larger modern horse size.

An animal called Eohippus is often cited as the first identifiable horse ancestor. Eohippus lived about 60 million years ago and is nicknamed the "dawn horse." It was a small, dog-sized animal with five toes on its front feet and three toes on its hind feet. The animal stood high on its toes, the tips of which were covered with strong little hooves. The teeth were the browsing type that had small bumps like those on human molars, but which more closely resembled those of a pig. Scientists estimate that this little horse was about 35 centimeters (14 inches) high and weighed a little over 5 kilograms (12 pounds).

The next candidate for selection in the fossil record is Hyracotherium, an animal that lived about 55 million years ago. Hyracotherium was more horselike than Eohippus, with its skeleton showing the characteristics that became unique to horses. The skull was longer and larger, and had a shallow basin at the end of shortened nasal bones where the nose is. The lower jaw was bigger and stronger than its relatives. The top and bottom incisors, or front teeth, met squarely and formed a "nipping-type" set of teeth. The back of the head no longer sloped backward but was now straight up and down. The neck bones were shaped so that the neck not only was longer, but could be rotated upward. Eventually, this feature helped the descendants of Hyracotherium to reach downward for grasses. Scientists believe that Hyracotherium (and many other species of horses at this time) had a short, prehensile proboscis, or snout, that could pick tasty leaves from high up in trees and bushes.

The legs of Hyracotherium were longer than those of Eohippus and other horses. The front legs of its ancestors had been about 40 percent longer than the hind legs, but the two sets of legs of Hyracotherium were more evenly lengthened. The feet began to change shape as their function for running became greater. The carpals and tarsals (wrist and ankle bones) became smaller and more square. The metacarpals and metatarsals (equivalent to the bones of a human palm) were longer and more slender. The wrist and ankle became more stabilized to prevent side-to-side motion and aid in more efficient running. One of the ankle bones, the astragalus, formed a unique notch where it met the lower leg bone, the tibia. This permitted greater force to be exerted on the foot when pushed against for running. In the wrist, the carpals interlocked with the lower row, providing a stronger pull stroke when running.

These trends continued in species named Orohippus and Mesohippus. The fossil record reveals a divergence of evolution around the time of Mesohippus, about 34 million years ago. One line contained the species Kalobatippus and Hypohippus, and died out with Megahippus. The other line, which leads to Equus, contained Miohippus and a tiny Archaeohippus and continued the skull and leg transformation. Archaeohippus was not highly successful, and its lineage died out relatively quickly. The ankle and wrist of Miohippus and its ancestors continued to strengthen, and the legs finally lengthened so that the animal stood higher in front than in the back. Mesohippus was the first ancestor of the horse to have one fewer front toe, although all the remaining horses eventually had three toes on each foot.

By the Oligocene (the end of the Tertiary epoch), major changes in the horses began to take place. The forest dwellers were no longer dominant, and horses who ate the newly rising C4 grasses began to spread into the great grasslands. These horses were larger, with increasingly long legs, and were able to explore new territory. The wrist and ankle bones continued to become more square and flat so that the force of running would not destabilize the foot. The side-to-side motion of the wrist and ankle was reduced to prevent wobbling, with the back-and-forth motion becoming stronger.

The trend toward an enlarged skull continued for the rest of horse history. The teeth, which were so important for grazing on tougher grasses, lost their roots and became hypsodont, or very high-crowned. One of the most identifiable characteristics of the horse is complex enamel, the tough outer coating of the tooth. Enamel resists the grinding actions of chewing. During the evolution of the horse, the enamel on the molars infolded from the sides, increasing the number of bumpy grinding surfaces. This trend continued for millions of years as horses ate more and more fibrous food. Many scientists believe that horses have the most complex and resistant teeth of almost all the large mammals. Some rodents have complex teeth, but like horses, they eat tough, fibrous foods, like seeds and silica-containing grasses.

The skeleton of the horse continued to grow from about 24 million years ago to the present. While the legs got longer and longer, the scapular (shoulder bone) and pelvis (hip bones) stayed relatively the same size. The neck and back elongated. This change resulted in two advantages for the horse. First, it allowed the horse's head to flex down to the ground to get the grasses. Second, the longer back gave greater flexure for a fast running pace. When an animal like a horse or cheetah runs, one of the important parts of the running pace is the springlike flexure of the back. Some species of horses that showed these changes were Parahippus, Merychippus,Neohipparion, Pliohippus (the first single-toed horse), Dinohippus, Hippidion, and Equus.

Hippidion and Equus lived at the same time, but Hippidion became extinct sometime in the Pleistocene. By this time, horses were gone from North America and it is believed that only a few populations continued in remote places. One population—a small, stocky, pony-type horse resistant to cold and wet—was discovered in northwest Europe. Another population—horses that were larger and resistant to heat—was found in central Asia. These central Asian horses were the ancestors of the desert horses of today.

The horse was reintroduced to North America by the Spanish during their explorations in the early sixteenth century. Many escaped or were let go and are the ancestors of the wild mustang. Horses now thrive all over the world. They are considered animals of beauty and grace and many cultures, such as the Native Americans of the North American plains and nomadic peoples in Mongolia, depend on the horse.

see also Biological Evolution; Physiology.

Brook Ellen Hall

Bibliography

MacFadden, Bruce. Fossile Horses: Systematics, Paleobiology, and Evolution of the Family Equidae. Cambridge, U.K.: Cambridge University Press, 1994.

Simpson, George Gaylord. Horses: The Story of the Horse Family in the Modern World and Through Sixty Million Years of History. New York: Oxford University Press, 1951.

Internet Resources

The International Museum of the Horse. Lexington, Kentucky. <http://www.imh.org/imh/kyhpl1a.html#xtocid224361>.

The Equine Studies Institute. Ed. Deb Bennett. Smithsonian Institution. <http://www.equinestudies.org/historical.htm>.

Horses. PBS/Nature. <http://www.pbs.org/wnet/nature/horses/>.

The Florida Museum of Natural History. <http://www.flmnh.ufl.edu>.

Horses

Horses are members of the family Equidae, which includes the wild asses of Africa and Asia and the zebras of African plains and mountains . The origins of horse-like mammals have been traced back some 55 million years to a small dog-sized, plant-eating animal known as Hyracotherium. More recently, during the Pliocene and Miocene periods (which ended some 1.5-2 million years ago) horses and their relatives as we know them today were probably the most abundant medium-sized grazing animals in the world. Since then, every species has experienced a major reduction in population size.

One wild horse, the tarpan, a small, shy, grey species lived on the Russian steppes of Eurasia until some time in the eighteenth century, when it became extinct because of overhunting and cross-breeding with domesticated species. Almost nothing is known about this animal apart from scant information in a few museums. The only other true wild horse, the slightly larger Prze walski's horse (Equus przewalskii), is now also thought to have gone extinct in the wild as recently as the mid 1960s. Some members of this species were, however, preserved in captivity so at least some representatives of this ancient lineage remain.

Horses are grazing animals of wide open plains, where constant vigilance is necessary in order to avoid predators such as lions, tigers, leopards, and wild canids. Apart from their keen senses of vision , hearing , and smell , horses are well equipped to outrun most potential attackers. Wild horses also undergo extensive seasonal migrations in search of optimal feeding and watering habitat . The feet of these hoofed animals (perissodactyls) are modified for agility and rapid movement. Horses have light feet with just one toe and, when moving, the hoof is the only part of the foot to touch the ground. Horses are also characterized by their long, slender legs, capable of a steady, prolonged movement or a long, striding gait. A deep chest allows for their large lungs, as well as the animal's large stomach, which is important for digesting the great amounts of relatively bulky plant materials.

Grasses and herbs form a major part of the diet. While these materials are relatively abundant, they are often not very nutritious, being low in protein and difficult to digest. Horses eat large quantities of plant materials each day and must be able to transform this into energy and nutrition . Plant cells are composed of cellulose , which the digestive system of few mammals is capable of breaking down. To assist with this process horses and their relatives rely on microorganisms within the large intestine and colon to break down and ferment their bulky diet. In contrast to ruminating animals such as deer and cattle, horses have a small and relatively simple stomach in which proteins are digested and absorbed. The digestive system of horses is far less efficient than that of a cow, for example, which means that the former must eat considerably more of the same materials in order to acquire a similar amount of energy.

Przewalski's horse is closely related to the domestic species (Equus caballus), but is distinct in its appearance. Reaching more than 7 ft (2 m) at the shoulder, and with a length of almost 8 ft (2.5 m), these horses are a dark bay-dun color with a much lighter underside and muzzle patch. The dark mane narrows to a single, narrow dorsal stripe along the back, ending in a black tail. Early Stone Age cave paintings feature many illustrations of horses that closely resemble this species. It was formerly widespread in steppe and semiarid habitats of Kazakhstan, Sinkiang, Mongolia, and parts of southern Siberia. The Przewalski's horse first became known to Western science in 1879, when it was discovered by a Polish explorer after whom the horse is named. Although there are no known estimates of the initial population size, by the early twentieth century it was already rare and found only in parts of southern China and Mongolia.

These animals were once highly prized by Mongolian people for their stamina. The wild herds once also provided semi-nomadic tribes with an essential supply of milk, meat, and hides, the latter being used for clothing as well as construction materials for their hut-like homes. Although the species is now extinct in its native habitat, sufficient animals are kept in zoological collections to enable a systematic program of captive breeding to take place. As a result of these efforts, there are now more than 1,000 individuals in captivity in many parts of the world. Apart from the hopes of conservationists to see this horse returned to its natural habitat, there is also a strong national desire amongst people in Mongolia to see these animals returned to the plains of its rightful heritage.

In their natural habitat, wild horses live in herds that consist of a number of mares, a single stallion, and foals and colts of a wide age span. The stallion is responsible for leading the herd to safe watering and feeding grounds and for protecting the females and young from predators. Stallions are extremely protective of their herds, and fights with other males who attempt to overthrow the stallion are common. Male horses fight with their hooves and teeth, especially the enlarged canines of the lower jaw—a prominent feature on mature males. A wide range of facial and other expressions are used to help avoid conflicts or to ensure that these are of short duration, as animals risk injury in such sparring events. Baring the teeth and curling the lips, while at the same time flattening the ears, is one of the most aggressive threats, while a number of vocalizations and stomping movements with the feet are also used to enhance the meaning of the gestures.

Almost everything we know about the social life of these animals is based on observations of semi-wild Przewalski's horses and feral populations of domestic horses. In the Przewalski's horse, young are born from April to June, following a gestation period of about 330 days. Mares usually bear a single foal which, shortly after birth , is able to stand up and follow its mother—an essential ability if the foal is not to fall prey to ever-vigilant predators. Foals remain close to their mothers for the first few weeks of life and do not become independent until they are almost two years old. Following this, they remain with the herd for several more years until they mature. In a natural situation, males are driven away from the herd as they reach sexual maturity. These solitary males usually join with other males to form small bachelor herds. Females, in contrast, may remain with the herd they were born into and will, in time, breed with the dominant male of the herd.

The precise origins of the domestic horse are not known but they likely arose from either the tarpan or Przewalski's horse. The earliest records of domestication are unclear and it is possible that this took place simultaneously in different parts of the world. Some reports suggest that it was attempted as early as 4000 b.c. in Mesopotamia and China, while evidence suggests that by 2000 b.c. domesticated horses were in use in China. Since then, horses have been bred for a number of purposes and there are now thought to be more than 180 different breeds. The powerful Shire horses were bred as draught animals in England, while most modern thoroughbreds, bred for their speed, stamina, and grace, are derived from breeding other species with primarily Arabian horses. The increasing spread of agriculture almost certainly played an important role in the use of domesticated species for draught purposes, but others were also bred and crossbred for their hardiness in extreme climates. Horses have also featured heavily in warfare, and many battles have been won and empires taken by mounted warriors.

Wild horses have suffered considerably since the arrival of humans on Earth . Horses and asses were once widely harvested for their meat and skins, particularly in parts of Asia. Elsewhere, the integrity of true wild species became diluted as domestic species interbred with wild animals. Natural changes may also have had some role to play in the demise of the wild horse, but it is more likely that human encroachment on the great plains of Asia, with spreading agriculture, has had the greatest and most long-term effect.

It is now too late to protect the last true wild horses, but considerable efforts are required to ensure that the last member of this ancient lineage, Przewalski's horse, and its natural habitat are protected in a manner that would enable this species to be reintroduced to its native habitat. Consideration should also be given to the preservation of wild stocks of domesticated varieties, such as the mustangs of North America , the Dartmoor and Exmoor ponies of Great Britain, and the brumbies of Australia , where these species have a role to play in maintaining the ecology of their respective habitats. In some countries, however, feral horses have caused considerable destruction to local plants and control programs are required to limit herd size so that they do not cause irreversible damage to fragile ecosystems. In other regions, feral horses play a useful role in cropping long coarse grasses, which helps keep the ecosystem open for other smaller, more fastidious grazing animals and plants. Some plants are known to germinate only when their seeds have passed through a horse's digestive system, as many of these plants may have evolved at a time when large herds of wild horses roamed the plains and acted as natural seed dispersers.

See also Livestock.