The horse (Equus ferus caballus) is a hoofed (ungulate) mammal, a subspecies of one of seven extant species of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today. Humans began to domesticate horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC; by 2000 BC the use of domesticated horses had spread throughout the Eurasian continent. Although most horses today are domesticated, there are still endangered populations of the Przewalski's Horse, the only remaining true wild horse, as well as more common feral horses which live in the wild but are descended from domesticated ancestors.
There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior. Horses are anatomically designed to use speed to escape predators, and have a well-developed sense of balance and a strong fight-or-flightmares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under saddle or in harness between the ages of two and four. They reach full adult development by age five, and have an average lifespan of between 25 and 30 years.
Horse breeds are loosely divided into three categories based on general temperament: spirited "hot bloods" with speed and endurance; "cold bloods", such as draft horses and some ponies, suitable for slow, heavy work; and "warmbloods", developed from crosses between hot bloods and cold bloods, often focusing on creating breeds for specific riding purposes, particularly in Europe. There are over 300 breeds of horses in the world today, developed for many different uses.
Horses and humans interact in many ways, not only in a wide variety of sport competitions and non-competitive recreational pursuits, but also in working activities including police work, agriculture, entertainment, assisted learning and therapy. Horses were historically used in warfare. A wide variety of riding and driving techniques have been developed, using many different styles of equipment and methods of control. Many products are derived from horses, including meat, milk, hide, hair, bone, and pharmaceuticals extracted from the urine of pregnant mares. Humans provide domesticated horses with food, water and shelter, as well as attention from specialists such as veterinarians and farriers.
Horse anatomy is described by a large number of specific terms, as illustrated by the chart to the right. Specific terms also describe various ages, colors and breeds.
Depending on breed, management and environment, the domestic horse today has a life expectancy of 25 to 30 years. It is uncommon, but a few animals live into their 40s and, occasionally, beyond. The oldest verifiable record was "Old Billy", a 19th-century horse that lived to the age of 62. In modern times, Sugar Puff, who had been listed in the Guinness Book of World Records as the world's oldest living pony, died in 2007, aged 56.
Regardless of a horse's actual birth date, for most competition purposes an animal is considered a year older on January 1 of each year in the northern hemisphere and August 1 in the southern hemisphere. The exception is in endurance riding, where the minimum age to compete is based on the animal's calendar age.A very rough estimate of a horse's age can be made from looking at its teeth
The following terminology is used to describe horses of various ages:
Foal: a horse of either sex less than one year old. A nursing foal is sometimes called a suckling and a foal that has been weaned is called a weanling. Most domesticated foals are weaned at 5 to 7 months of age, although foals can be weaned at 4 months with no adverse effects.
Yearling: a horse of either sex that is between one and two years old.
Colt: a male horse under the age of four. A common terminology error is to call any young horse a "colt", when the term actually only refers to young male horses.
Filly: a female horse under the age of four.
Mare: a female horse four years old and older.
Stallion: a non-castrated male horse four years old and older.Some people, particularly in the UK, refer to a stallion as a "horse".
A ridgling or "rig" is a male horse which has an undescended testicle or is improperly castrated. If both testicles are not descended, the horse may appear to be a gelding, but will still behave like a stallion.
Gelding: a castrated male horse of any age, though for convenience sake, many people also refer to a young gelding under the age of four as a "colt".
In horse racing, the definitions of colt, filly, mare, and stallion may differ from those given above. In the UK, Thoroughbred horse racing defines a colt as a male less than five years old, and a filly as a female less than five years old. In the United States, both Thoroughbred racing and harness racing defines colts and fillies as four years old and younger.
Horses and humans have an ancient relationship. Asian nomads probably domesticated the first horses some 4,000 years ago, and the animals remained essential to many human societies until the advent of the engine. Horses still hold a place of honor in many cultures, often linked to heroic exploits in war.
There is only one species of domestic horse, but around 400 different breeds that specialize in everything from pulling wagons to racing. All horses are grazers.
While most horses are domestic, others remain wild. Feral horses are the descendents of once-tame animals that have run free for generations. Groups of such horses can be found in many places around the world. North American mustangs, for example, are the descendents of horses brought by Europeans more than 400 years ago.
Wild horses generally gather in groups of 3 to 20 animals. A stallion (mature male) leads the group, which consists of mares (females) and young foals. When young males become colts, at around two years of age, the stallion drives them away. The colts then roam with other young males until they can gather their own band of females.
The Przewalski's horse is the only truly wild horse whose ancestors were never domesticated. Ironically, this stocky, sturdy animal exists today only in captivity. The last wild Przewalski's horse was seen in Mongolia in 1968.