Horses can be found on every continent in the world, except Antarctica. Despite their diversity, all modern horse breeds are part of a single species called Equus caballus. But where on our planet do horses actually originate from?
The first ancestral horse, Eohippus, appeared in North America around 55 million years ago. Early horses migrated to Eurasia via the Bering land bridge, but around 10 000 years ago, Equus went extinct in North America. Modern horses all originate from those that evolved in the Eurasian steppes.
At the beginning of their evolution in North America, horses were the size of small dogs! However, these tiny forest-dwelling horses are not the direct ancestors of the wild mustangs that roam across western America today. Horses have a long and complex evolutionary history, of which the last 5 millennia are closely linked with human history.
Where do Horses Live in the Wild?
Around the world, there are many populations of horses that live freely in the wild without any care or interference from humans. The most famous example is the Mustangs in the North American West.
The largest population of free-roaming horses in the world can be found in Australia. There are more than 400 000 wild Brumbies that live in the wilderness of Australia.
Other isolated populations of free-roaming horses in North America can be found on Sable Island, near Nova Scotia, Assateague Island, near Virginia and Maryland, Cumberland Island, in Georgia, and Vieques Island near Puerto Rico.
Smaller groups of free-roaming horses can be found in Portugal – the Sorraia in the southern plains, and the Garrano in mountainous northern parts. There are also groups living in the western Dinaric Alps of Bosnia and Herzegovina, as well as in northeastern India, in the state of Assam.
Wild Horses vs Feral Horses
Although there are many populations of free-roaming, untamed horses around the world, these are not considered to be truly “wild” horses. Because they descend from ancestors that were once domesticated, they are called feral horses or Equus ferus.
There remains only one extant species of truly wild horse – Przewalski’s horse or Equus przewalskii. These horses have never been domesticated, ranging freely across the Eurasian Steppes, from the Ural Mountains to Mongolia.
The Evolution of Horses
Due to equines being so important to human development, their evolutionary history is incredibly well-researched and documented.
The origin of the first ancestral horse dates back to the Eocene epoch (56 million to 33.9 million years ago). Around 55 million years ago, Eohippus, the ‘dawn horse’, appeared in North America. Standing less than 5 hands tall, it was about the size of a terrier, and had padded feet with four hooves on the front feet and three on the hind feet. This tiny ancient horse was forest-dwelling, browsing on leaves from shrubs.
Changes in the climate around 20 million years ago, caused grasslands to become more widespread. It caused a boom in the evolution of ancient equines, with new species of horses rapidly developing to take advantage of grassland niches.
By around 10 million years ago, there had evolved about a dozen different species of ancient horses. These species lived during the same time and occupied the same habitats. All of them roamed the Great Plains of North America, some living in open grassland, while others stayed in the forest.
These ancient horses varied greatly in size, body, and foot shape:
- Mesohippus, which evolved around 33.9 million years ago, was slightly more recognizable as a horse, than Eohippus. It had a more muzzle-like snout, and longer, more slender legs. But on each foot, it had three toes and a footpad, and its teeth were suited to browsing. It only weighed about 45 kilograms.
- Miohippus evolved around 23 million years ago. It looked horse-like, but with three-toed feet. They were able to migrate out of North America into Eurasia via the Bering land bridge.
- Merychippus evolved around 15 million years ago. It looked similar to a modern pony. Standing about 10 hands and weighing 100kg, its skull was like that of a modern horse, with teeth suited to grazing. The bones in the lower legs had fused, enabling them to run fast. They still had three does, but two had shrunken, and they no longer had a footpad. The one large toe had a hoof.
- Dinohippus, which evolved around 11 million years ago, looked very much like a modern horse. It had single-toed, hooved feet, and teeth suited to grazing.
- Equus, the genus that modern horses, donkeys, and zebras are part of, evolved around 4 million years ago. With their long legs built for speed and endurance, and their teeth adapted for grazing, they were successful and spread from the North American Plains to South America, and throughout Eurasia and Africa by 2.6 million years ago.
There was an evolutionary trend towards larger body size, fewer hooves on each foot, reduced footpads, longer legs, fused lower leg bones, larger brain size with increased complexity, a longer muzzle, and teeth suited for grazing.
Where Do Modern Horses Originate?
Some species of the early horses that evolved in North America were able to migrate to South America and to Eurasia via the Bering land Bridge, which connected North America to Asia until the late Pleistocene epoch.
At the end of the last glacial period, about 10 000 years ago there was a sudden mass extinction event that wiped out more than 50% of all the large mammals in North and South America. Ancient horses became extinct, along with mammoths, giant sloths, and mastodons. Sea level rise flooded the Bering land bridge, so animals could not migrate back to North America.
Throughout Europe, Africa, and Asia, Equus continued to evolve into all the modernspecies that make up the genus today, including Equus caballus. Therefore, while the genus Equus is native to North America in that it evolved there, all modern horses found in North America today are descended from the equids of Europe and Asia.
Only two of the species that evolved during this time survived into recorded history. The tarpan, or European wild horse (Equus ferus ferus) and Przewalski’s horse, Equus ferus przewalskii.
The tarpan was native to eastern Europe and the Ukranian steppes. There was a subspecies of tarpan that lived in forests, called the forest horse. Forest horses were recorded in the 19th century in Spain, France, Great Britain, and Sweden. Sadly, the species is extinct today. The last surviving tarpan died in a Russian zoo in 1909.
Przewalski’s horse, also known as the Mongolian wild horse, is native to the Central Asian steppes. It is the only truly wild horse on earth. It is the only breed of wild horse that is genetically distinct from domesticated horses.
It is believed that the tarpan, forest horse and Przewalski’s horse are the ancestors of domestic horses breeding stock. It is thought that warm-blooded breeds of horses came from Przewalski’s horse and the tarpan, while cold-booded breeds came from the forest horse.
Domestication of Horses
All over the world, horses have been key to human development; as a source of meat and milk, providing us with transport, driving agriculture, and powering warfare. But how did humanity’s close relationship with horses begin? When and where were horses first domesticated?
Of the world’s 148 large, terrestrial, mammalian herbivores, only 14 were domesticated. Geographer and historian, Jared Diamond, proposes six characteristics that wild animals must have for them to be successfully domesticated:
- Efficient diet – herbivores are easier to feed than carnivores.
- Fast growth rate – reach a mature or useful age within a few years.
- Can breed in captivity – does not require capturing wild animals continuously.
- Pleasant temperament – safe to keep close to humans.
- Do not tend to panic – makes animals easier to work with.
- Social structure – live in hierarchical herds that humans can take advantage of.
Horses have all six of these characteristics, which is why humans were able to successfully tame and eventually domesticate them.
Evidence for Domestication
Paleontologists and archaeologists have used a combination of equine skeletal remains, changes in the distribution of horse remains, cave paintings, horse related artefacts from archaeological sites, and genetic analysis to hypothesize when and how the domestication of horses happened.
When and Where Were Horses First Domesticated?
Horses appear in Stone Age cave paintings that date back over 30 000 years, however these were likely wild horses, that Paleolithic humans hunted for meat.
A large body of evidence supports the theory that horses were first domesticated in the western Eurasian Steppes. Archaeological evidence suggests that horses had been domesticated in the region north of the Black Sea, from Ukraine to Kazakhstan, as early as 6000 years ago.
Genetic analysis of domestic horses shows that there is a high degree of genetic diversity in the genome, suggesting that there was more than one “domestication event” in history, and that separate groups of people, that had no communication with each other, independently started domesticating horses. It also suggests that wild horses were used to supplement domesticated breeding stocks.
Based on archaeological evidence, it is estimated that by 4000BC humans had begun to drive horses using a bit, and that horses had become a valuable asset to humans in building civilizations.
How Were Horses First Domesticated?
Studies on ancient human settlements in northern Kazakhstan, revealed evidence of how the earliest domesticated horses were kept. Evidence of circular corrals have been found near the settlements, and soil analysis from inside these corrals showed that it contained many layers of horse manure.
It is likely that domestication started with a wild mare being killed for meat, leaving behind a young calf. Humans could easily have kept young horses, raising them in corrals. Female horses would have been milked, and later on may have started being ridden.
Horses from Around the World
Because the history of horse breeding is so well documented, it is possible to trace the geographic origins of certain breeds.
Heavy horses, used for farm work and pulling carts, have their origins in Europe. Belgian draft horses were bred in Belgium, the Clydesdale was developed in Scotland, the Percheron in France, and the Shire (the world’s largest horse breed) was bred in England.
Small horse breeds, or ponies, also have their origins in Europe. The Connemara Pony is indigenous to Ireland, the Shetland Pony comes from the Scottish Shetland Islands and the Welsh Pony comes from Wales.
Light horses, that are mainly used for pleasure riding and sport today, have more diverse origins. The Akhal-Teke was developed in Turkmenistan, and the Andalusian was first bred in Spain. Arabians, as their name suggests, were developed in the Middle East. The Thoroughbred and Cleveland Bay comes from England.
The Hanoverian horse was bred in Germany, the Lipizzaner originates from Austria and Slovenia, and the Trakehner was developed in the area that is today Lithuania.
Horses were brought to the Americas by Spanish colonists early in the 16th century. All the American horse breeds that were developed are descended from the Spanish horses that were introduced.
For example, the American Paint horse, Quarter horse, Saddlebred, Standardbred Appaloosa, Morgan, Missouri Fox Trotting horse, and Tennessee Walking horse are all breeds that originate in the United States from Eurasian breeding stock.
Answering the question of where horses come from is not straightforward, as horses have a complex evolutionary history.
The first ancestral horse originated in North America about 55 million years ago. However, horses did not remain in North America. By about 20 million years ago, many different horse species began migrating out of North America into Asia and Europe via the Bering land bridge. By about 2 million years ago, the genus Equus, had spread all the way into South America and Africa.
At around 10 000 years before present, near the end of the last glacial period, there was a mass extinction events in North and South America. All the horse species on these continents went extinct.
Horses in Europe, Asia, and Africa kept evolving and around 6000 years ago humans began the process of domesticating horses. They were a valuable source of food, transport and power and played a huge role in shaping ancient civilizations.
Spanish colonists introduced horses back to the Americas at the beginning of the 16th century. All domesticated and feral horses in North America today originate from the horses that were developed in Eurasia.