Encyclopedia
The
horse is a large
odd-toed ungulate mammal, one of ten modern species of the genus
Equus. Horses have long been one of the most economically important
domesticated animals, and have played an important role in the
transport of people and cargo for thousands of years. While isolated
domestication may have occurred as early as 10,000 years ago, clear evidence of widespread horse use by humans dates to around 2000 BC. Since they were domesticated, selective breeding has resulted in many breeds. Some have been bred so that they can be
ridden, usually with a
saddle, while other breeds can be
harnessed to pull objects like
carriages or
plows. In some cultures, horses are a source of food, including
horse meat and sometimes
milk; in other cultures it is taboo to eat them. Today, in wealthy countries, horses are predominantly kept for leisure and sporting pursuits, while they are still used as working animals in many other parts of the world.
Biology of the horse
Depending on breed, management, and environment, the domestic horse today has an average life expectancy of 25 to 30 years. A rare few domestic horses can live into their 40s, and, occasionally, beyond. The oldest verifiable record was "Old Billy," a horse that lived in the 19th century, believed to have lived to the age of 62.
Pregnancy lasts for 11 months and usually results in one
foal . Twins are rare. Horses, particularly colts, may sometimes be physically capable of reproduction at approximately 18 months but in practice are rarely allowed to breed until a minimum age of 3 years, especially females. Horses four years old are considered mature, though the age of achieving full growth also varies by breed and by individual genetics. Females 4 years and over are called mares and males are stallions. A castrated male is a gelding.
Depending on maturity, breed and the tasks expected, young horses are usually put under saddle and trained to be ridden between the ages of two and four, with three years being the most common practice. Although
Thoroughbred and
American Quarter Horse race horses are put on the track at as young as two years old in some countries , horses specifically bred for sports such as
show jumping are generally not entered into top-level competition until the age of five or six because their bones and muscles are not properly developed, nor is their training complete. In the strenuous sport of endurance riding, horses are not allowed to compete until they are a full 60 months old. In some cases, such as the training of
Andalusians or
Lipizzans in classical dressage, training under saddle begins as late as four years and the horses are not considered ready for public performance until the age of nine or ten.
The size of horses varies by breed. The cutoff in height between what is considered a horse and a
pony is always 14.2 or smaller
hands , though some smaller horse breeds are considered "horses" regardless of height. Light horses such as Arabians,
Morgans,
Quarter Horses,
Paints and
Thoroughbreds usually range in height from 14.0 to 17.0 hands and can weigh up to 1300 lb . Heavy or
draft horses such as the
Clydesdale, Belgian,
Percheron, and
Shire are usually at least 16.0 to 18.0 hands high and can weigh up to 2000 lb . Ponies are no taller than 14.2 hands, but can be much smaller, down to the
Falabella or
Shetland, which can be the size of a large dog. The
miniature horse is as small as or smaller than either of the aforementioned ponies but are considered to be very small horses rather than ponies despite their size. The difference between a horse and pony is not just a height difference. They have different temperaments, different conformation, and ponies often exhibit thicker manes, tails and overall hair coat.
Evolution of the horse
Horses and other equids are
odd-toed ungulates of the order Perissodactyla, a relatively ancient group of browsing and grazing animals that first arose less than 10 million years after the
dinosaurs became extinct. In the past, this order contained twelve families, but only three
families—the
horses and related species,
tapirs and
rhinoceroses—have survived till today. The earliest equids were found approximately 54 million years to the
Eocene period. The
Perissodactyls were the dominant group of large terrestrial browsing animals until the Miocene , when
even-toed ungulates, with stomachs better adapted to digesting
grass, began to out compete them.
The horse as it is known today adapted by evolution to survive in areas of wide-open terrain with sparse vegetation, surviving in an ecosystem where other large grazing animals, especially
ruminants, could not.
Horse evolution was characterized by a reduction in the number of toes, from five per foot, to three per foot, to only one toe per foot ; essentially, the animal was standing on tiptoe. One of the first true horse species was the tiny
Hyracotherium, which had 4 toes on each front foot and 3 toes on each back foot . Over about five million years, this early equids evolved into the
Orohippus. The 5th fingers vanished, and new grinding teeth evolved. This was significant in that it signaled a transition to improved browsing of tougher plant material, allowing grazing of not just leafy plants but also tougher plains
grasses. Thus the proto-horses changed from leaf-eating forest-dwellers to grass-eating inhabitants of the
Great Plains.
By the
Pleistocene era, as the horse adapted to a drier, prairie environment, the 2nd and 4th toes disappeared on all feet, and horses became bigger. These side toes were shrinking in
Hipparion and have vanished in modern horses. All that remains are a set of small
vestigial bones on either side of the
cannon bone, known informally as
splint bones, which are a frequent source of splints, a common injury in the modern horse.
Domestication of the horse and surviving wild species
Competing theories exist as to the time and place of initial domestication. The earliest evidence for the
domestication of the horse comes from
Central Asia and dates to approximately 4,500 BC.
Archaeological finds such as the
Sintashta chariot burials provided unequivocal evidence that the horse was definitely domesticated by 2000 BCE.
Wild species
Most "wild" horses today are actually
feral horses, animals that had domesticated ancestors but were themselves born and live in the wild, often for generations. However, there are also some truly wild horses whose ancestors were never successfully domesticated.
Historical wild species include the Forest Horse , thought to have evolved into
Equus ferus germanicus, and may have contributed to the development of the heavy horses of northern
Europe, such as
Ardennais.
There is a theory that there were additional "proto" horses that developed with adaptations to their environment prior to domestication. There are competing theories, but in addition to the Forest Horse, three other types are thought to have developed:
- A small, sturdy, heavyset pony-sized animal with a heavy hair coat, arising in northern Europe, adapted to cold, damp climates, somewhat resembling today's Shetland pony
- A taller, slim, refined and agile animal arising in western Asia, adapted to hot, dry climates, thought to be the progenitor of the modern Arabian horse and Akhal-Teke
- A dun-colored, sturdy animal, the size of a large pony, adapted to the cold, dry climates of northern Asia, the predecessor to the Tarpan and Przewalski's Horse.
The
tarpan,
Equus ferus ferus, became extinct in 1880. Its genetic line is lost, but its phenotype has been recreated by a "breeding back" process, in which living domesticated horses with primitive features were repeatedly interbred. Thanks to the efforts of the brothers Lutz Heck and Heinz Heck , the resulting
Wild Polish Horse or
Konik more closely resembles the tarpan than any other living horse.
Przewalski's Horse , a rare Asian species, is the only true wild horse alive today.
Mongolians know it as the
taki, while the
Kirghiz people call it a
kirtag. Small wild breeding populations of this animal, named after the
Russian explorer
Przewalski, exist in Mongolia. There are also small populations maintained at zoos throughout the world.
Other truly wild equids alive today include the
zebra and the
onager.
Feral horses
Wild animals, whose ancestors have never undergone domestication, are distinct from
feral ones, who had domesticated ancestors but were born and live in the wild. Several populations of feral horses exist, including those in the western
United States and
Canada , and in parts of
Australia and
New Zealand . Isolated feral populations are often named for their geographic location:
Namibia has its Namib Desert Horses; the Sorraia lives in
Portugal;
Sable Island Horses reside in
Nova Scotia,
Canada; and
New Forest ponies have been part of
Hampshire,
England for a thousand years.
Studies of feral horses have provided useful insights into the behavior of ancestral wild horses, as well as greater understanding of the instincts and behaviors that drive "tame" horses.
Other modern equids
- Main artice: Equidae for full species list.
Other members of the horse family include
zebras,
donkeys, and
onagers. The Donkey, Burro or Domestic Ass, Equus asinus, like the horse, has many breeds. A
mule is a hybrid of a male ass and a mare, and is usually infertile. A hinny is the less common hybrid of a female ass and a stallion. Breeders have also tried crossing various species of zebra with mares or female asses to produce "zebra mules" . This will probably remain a novelty hybrid as these individuals tend to inherit some of the undomesticated nature of their zebra parent, but they may inherit the zebra's resistance to
nagana pest: zorses, also called
zebroids, have been used in Central African game parks for light haulage.
Horse behavior
Horses are prey animals with a well-developed Fight-or-flight instinct. Their first response to threat is to flee, although they are known to stand their ground and defend themselves or their offspring in cases where flight is not possible, such as when a foal would be threatened. Through selective breeding, some breeds of horses have been bred to be quite docile, particularly certain large draft horses. However, most light horse riding breeds were developed for speed, agility, alertness and endurance; natural qualities that extend from their wild ancestors.
Horses are herd animals, and become very attached to their species and to humans. They communicate in various ways, such as nickering, grooming, and body language. Some horses will become flighty, and hard to manage if they are away from their herd. This is called being "herd-bound."
Horses within the human economy
Around the world, horses play a role within human economies, for leisure, sport and working purposes. To cite one example, the American Horse Council estimates that horse-related activities have a direct impact on the economy of the
United States of over $39 billion, and when indirect spending is considered, the impact is over $102 billion.
In wealthier,
First World, industrialized economies, horses are primarily used in recreational pursuits and competitive sports, though they also have practical uses in police work, cattle
ranching, search and rescue, and other duties where terrain or conditions preclude use of motorized vehicles. In poorer,
Third World economies, they may also be used for recreational purposes by the elite population, but serve a much wider role in working pursuits including
farming,
ranching and as a means of transportation. To a very limited extent, they are also still used in
warfare, particularly in regions of extremely rugged terrain.
Horses for leisure
People in many nations use horses for leisure. Many people find being around horses soothing and therapeutic and choose to keep horses as companion animals.
Horses for sport
Horses are used in two ways for sports: as competitors, and as mounts for human competitors. Horses as competitors are trained to be ridden or driven in a particular event. Examples include
barrel racing,
eventing, carriage driving,
dressage, and
show jumping. Although scoring varies by event, most emphasize the horse's speed, maneuverability, obedience and/or precision. Sometimes the equitation of the rider is also considered.
Sports such as
polo and horseball use horses as mounts on which the human competitors ride. Although their riders are the primary competitors, horses serve as a necessary part of the game. In
jousting, for example, the main goal is for one rider to dismount the other. Buzkashi is a game played throughout
Central Asia, the aim being to capture a goat while on horseback.
Although the horse assists this process and requires specialized training to do so, the details of its performance are not judged, only the result of the rider's actions.
The most widely-known use of horses for sport is
horse racing, seen in almost every nation in the world. There are three types: "flat" racing, steeple chasing, i.e. racing with jumps, and
harness racing, where horses trot towing a small cart where the driver sits. Most racing horses in the developed world are
Thoroughbreds, a breed which can reach speeds up to 40 mph/70 km/h. In the case of a specialized sprinting breed, the
American quarter horse, speeds over 50 mph have been clocked. In
harness racing, speeds over 30 mph have been measured.
A major part of the economic importance of horse racing, as for many sports, lies in the
gambling associated with it.
Horses for work
There are certain jobs that horses do very well, and no amount of technology appears able to supersede.
Mounted police horses are still effective for crowd control. Cattle
ranches still require riders on horseback to round up cattle that are scattered across remote, rugged terrain. Search and rescue organizations in some countries depend upon mounted teams to locate people, particularly hikers and hunters, who are lost in remote areas.
Some land management practices such as
logging can be more efficiently managed with horses, to avoid vehicular disruption to delicate soil in areas such as a nature reserve. Forestry rangers may use horses for their patrols.
In poor countries such as
Romania,
Kyrgyzstan, and many parts of the
Third World, horses, donkeys and mules are widely used for transport and agriculture, especially for pulling plows or carts. In areas where roads are poor or non-existent, fossil fuels are scarce, and the terrain rugged, riding horseback is still the most efficient way to get from place to place.
Horses used for entertainment and culture
Horses today also are used to re-enact their historical work purposes. A famous example are the Budweiser
Clydesdales, a team of
draft horses who pull a beer wagon in a manner similar to that used prior to the invention of the modern motorized truck.
Horses are used, complete with equipment that is authentic or a meticulously recreated replica, to enact various historical battles. Popular subjects include American
Revolutionary War and
Civil War reenactments, as well as battles of the 19th century between the U.S.
Cavalry and
Native Americans.
Horses also are used to reenact specific periods of history, or to preserve cultural resources, or for ceremonial purposes. Examples include the use of horses at tourist destinations such as
Colonial Williamsburg. Countries such as the
United Kingdom still use horse-drawn carriages to convey royalty and VIPs to and from certain culturally significant events.
Horses are frequently used in movies to add authenticity to historical dramas as well as adding charm to films set in the modern-day, or even futuristic dramas.
Horses used for therapeutic purposes
A form of physical therapy is Therapeutic horseback riding. People with both physical and mental disabilities have obtained medically beneficial results from riding. The movement of a horse strengthens muscles throughout a rider's body and promotes better overall health. In many cases, riding has also led to increased mobility for the rider and sometimes has helped injured people regain the ability to walk. Soldiers injured in warfare have been known to use this form of physical therapy to regain movement in limbs or simply become accustomed to
prosthetic limbs. People who have cognitive or sensory disabilities benefit because riding requires attention, reasoning skills and memory.
The benefits of equestrian activity for people with disabilities has also been recognized with the addition of equestrian events to the
Paralympic Games.
"Equine-assisted" or "equine-facilitated" psychotherapy is a new but growing movement which uses horses as companion animals to assist people with mental illness. Actual practices vary widely due to the newness of the field; some programs include therapeutic riding. Non-riding therapies simply encourage a person to touch, speak to and otherwise interact with the horse. Even without riding, people appear to benefit from being able to connect to a horse on a personal level. People with mental illnesses can benefit from the interaction and relationships formed with both horses and people. Horses are also used in camps and programs for young people with emotional difficulties.
There also have been experimental programs using horses in
prison settings. Exposure to horses appears to improve the behavior of inmates in a prison setting and help reduce recidivism when they leave. A correctional facility in
Nevada has a successful program where inmates learn to train young mustangs captured off the range in order to make it more likely that these horses will find adoptive homes. Both adult and juvenile prisons in
New York,
Florida, and
Kentucky work in cooperation with the Thoroughbred Retirement Foundation to re-train former racehorses as pleasure mounts and find them new homes.
Horses in warfare
Horses were used in warfare for most of recorded history, dating back at least to the 19th century B.C. While mechanization largely has replaced the horse as a weapon of war, horses are still seen today in limited military uses, mostly for ceremonial purposes, or for reconnaissance and transport activities in areas of rough terrain where motorized vehicles are ineffective. Horses are also used to reenact historical battles; see Culture above. The training of the
war horse has vestiges in the disciplines of classical dressage and
eventing.
Horse products
- Horse meat has been used as food for animals and humans throughout the ages. It is eaten in many parts of the world and is an export industry in the United States and other countries. have been introduced in both the House and the Senate which would put an end to this practice in the United States. Its consumption is taboo in some cultures.
- Mare's milk is used by people with large horse-herds, such as the Mongols. They may let it ferment to produce kumis. Mares produce a lower yield of milk than cows, but more than goats and sheep.
- Horse blood was also used as food by the Mongols and other nomadic tribes.
- Premarin is a mixture of female hormones extracted from the urine of pregnant mares . It is a widely used drug for hormone replacement therapy. This horse product is especially controversial; see the Premarin article.
- Horsehide leather has been used for boots, gloves, jackets, baseballs, and baseball gloves. The saba is a horsehide vessel used in the production of kumis. Horsehide can be used to produce animal glue.
- Horse hooves can be used to produce hoof glue.
Specialized vocabulary
Because horses and humans have lived and worked together for thousands of years, an extensive specialized vocabulary has arisen to describe virtually every horse behavioral and anatomical characteristic with a high degree of precision.
In
horse racing the definitions of colt, filly, mare, and horse may differ from those given above. In the United Kingdom,
thoroughbred racing defines a
colt as a male horse less than five years old and a filly as a female horse less than five years old;
harness racing defines colts and fillies as less than four years old. Females older than colts and fillies become known as mares, while males become stallions or geldings .
The
anatomy of the horse comes with a large number of horse specific terms.
Horses exhibit a diverse array of coat colors and distinctive markings, and a specialized vocabulary has evolved to describe them. Often, one will refer to a horse in the field by its coat color rather than by breed or by sex. The genetics of the coat colors has largely been resolved, although discussion continues about some of the details.
The English-speaking world measures the height of horses in
hands. One hand is defined in British law as 101.6 mm, a figure derived from the previous measure of 4
Imperial inches. Horse height is measured at the highest point of an animal's
withers. Perhaps because of extensive selective breeding, modern adult horses vary widely in size, ranging from
miniature horses measuring 5 hands to draft animals measuring 19 hands or more. By convention, 15.2 hh
means 15 hands, 2 inches in height.
Horses versus ponies
Ponies are smaller than horses and stay that way through their lives. In general, to be a pony the equine in question must stand 14.2hh or lower at the withers. Many breeds do not grow bigger than this measurement of size, and part of the breed characteristics is pony. Therefore, any equine in that breed must be pony sized to be registered.
Ponies also tend to have certain
conformational characteristics: they tend to be stockier than horses, have shorter legs, wide barrels, and thick necks and heads.
There are exceptions to this general rule. Some breeds are pony sized, but called horses. Examples include the caspian horse which often stands only eleven or twelve hands, but it has the
conformation of a horse – refined head, clean legs and fine bones – rather than that of a pony.
Other breeds, such as the Pony of the Americas or the
Welsh cob, share some features of horses but are still considered ponies.
Gaits
All horses move naturally with four basic gaits; these are referred to as
walk, trot or jog ,
canter or
lope , and
gallop.
Besides these basic gaits, additional gaits such as
pace,
slow gait,
rack, fox trot and
tölt can be distinguished. These special gaits are often found in specific breeds, and are referred to as "gaited" because they naturally possess additional "single-footed" gaits that are approximately the same speed as the trot but smoother to ride.
Technically speaking the so called "gaited horses" replace the standard trot which is a 2 beat gait with a four beated gait. This can be clearly heard when shod horses are riding on the street. The anatomy of the trot consists of the lifting a front hoof and a rear opposite sided hoof at the same time. This can be seen vividly when watching lippizaners on parade, and is similar to a dog's trot. A four beated gait occurs when only one foot at a time lifts off, and hence is called a "running walk". In a manner of speaking this is like the front legs being operated independently of the rear. A true gaited horse will rarely, if ever, trot; gaited horse foals will gait from birth. A pace is a two beat gait where the animal moves the front and rear legs of one side at the same time, similar to an elephant. This produces a ride that is not as jarring up and down as a trot but has a definite side to side or rocking motion, this is considered an undesireable gait by people in the gaited horse trade.
A trot is an up and down action of the legs whereas the true gaited horse generally has some sort of circular motion to the front hooves and a sliding or shuffling motion to the rear hooves, when done perfectly this produces a gait that is as fast and oftentimes faster than a trot and smooth enough that the rider feels as though in an easy chair. Through training a gaited horse may effectively be rendered a 3 gaited horse with only the walk, the special gait , and the gallop. This does not diminish the speed of the horse, the animal just has no need to lope/canter due to the speed that it can perform its' special gait.
Horse breeds with additional gaits include the Tennessee Walking Horse with its running walk, the American Saddlebred with its "slow gait" and rack, the
Paso Fino horse with the paso corto and paso largo and
Icelandic horse which are known for the tölt. The Fox Trot is found in several gaited breeds, most notably the Missouri Foxtrotter while some
Standardbreds,
pace instead of trot.
The origin of modern horse breeds
Horses come in various sizes and shapes. The
draft breeds can top 19 hands while the smallest miniature horses can stand as low as 5.2 hands . The Patagonian Fallabella, usually considered the smallest horse in the world, compares in size to a
German Shepherd Dog.
Different schools of thought exist to explain how this range of size and shape came about. One school, which we can call the "Four Foundations," described in the domestication section above, suggests that the modern horse evolved from multiple types of early domesticated pony and early domesticated horse; the differences between these types account for the differences in type of the modern breeds. A second school -- the "Single Foundation" -- holds only one breed of horse underwent domestication, and it diverged in form after domestication through human selective breeding . This question will most likely only be resolved once geneticists have finished evaluating the horse genome, analyzing
DNA and mitochondrial DNA to construct family trees. See:
Domestication of the horse.
In either case, modern horse breeds developed in response to the need of "form to function;" that is, the necessity to develop certain physical characteristics necessary to perform a certain type of work. Thus, light, refined horses such as the
Arabian horse or the Akhal Teke developed in dry climates to be fast and with great endurance over long distances, while the heavy draft horse such as the Belgian developed out of a need to pull plows. Ponies of all breeds developed out of a dual need to create mounts suitable for children as well as for work in small places like mine shafts or in areas where there was insufficient forage to support larger draft animals. In between these extremes, horses were bred to be particularly suitable for tasks that included pulling carriages, carrying heavily-armored
knights, jumping, racing, herding other animals, and packing supplies.
The
Icelandic horse provides an opportunity to compare contemporary and historical breed appearances and behavior. Introduced by the
Vikings into
Iceland over one thousand years ago, these horses did not subsequently undergo the intensive selective breeding that took place in the rest of Europe from the
Middle Ages onwards, and consequently bear a closer resemblance to pre-Medieval horses. The Icelandic horse is of small stature and has a four-beat
