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The majestic horse, embodying both power and grace, has left indelible hoofprints on the annals of human history.
Despite their ubiquitous presence in our lives and cultures, the origins of horses remains a captivating mystery to many.
What was the evolutionary journey of the horse, and how did the paths of horses and humans first intertwine in the dance of domestication?
As we delve into the distant past, this exploration unearths the intriguing lineage of horses and sheds light on the birth of our longstanding partnership with these noble beings.
Where Did Horses Originate From?
Horses originated in North America around 55 million years ago. Their ancestors migrated to Eurasia around 2-3 million years ago to give rise to the modern horse. Equid species went extinct in the Americas approximately 8,000 to 12,000 years ago.
Over the last few decades, numerous remains of primitive horses have been found on the North American continent.
In 1976, a team of archeologists uncovered fossils of the earliest ancestor of horses in Wyoming. No larger than a Beagle, the Eohippus was a herbivore that thrived during the Eocene Epoch.
What Are Horses Descended From?
Interestingly, paleontologists today have a more clear image of the horse’s evolution than of any other animal’s. Their evolutionary lineage takes us back 55 million years, when the earliest known horses were still living in forests instead of grasslands.
Horses as a species are descended from a small forest-dwelling herbivore called the Eohippus. Modern domesticated horses, however, likely descended from the Eurasian wild horse known as the Tarpan.
Being odd-toed ungulates, horses are closely related to rhinos and tapirs. Their last common ancestor, believed to be the Cambaytherium, walked the Earth around 54.5 million years ago. With the Eohippus, however, horses diverged from their cousins to become a distinct species.
When the ancestors of horses crossed the Bering Strait into Eurasia, they walked on a thick sheet of ice. On the new continent, several subspecies evolved, including the Eurasian wild horse or Tarpan (Equus ferus ferus). This species is thought to be the ancestor of all horses living today.
Considering its evolutionary history, the Tarpan survived surprisingly long. The last specimen died in a Russian zoo in 1909, although many believe it wasn’t a true Tarpan.
Today, we categorize all horse breeds into four main types: warmblood, draft, hot-blooded, and pony. One theory suggests that these types trace back to three Tarpan subspecies, namely:
- The “Warmblood” subspecies or “Forest Horse”, ancestor of warmblood breeds
- The “Draft” subspecies, the ancestor of draft and pony breeds
- The “Oriental” subspecies, the ancestor of hot-blooded breeds
Until recently, people regarded the Przewalski’s Horse as a truly wild horse breed similar to the Tarpan. However, a 2018 study has debunked this belief. According to the scientists, the Przewalski’s Horse descends from the earliest horses that underwent domestication around 5,500 years ago.
However, as this horse breed has 66 chromosomes while all other horses have 64, it cannot be a descendant of the Tarpan. Hence the real origins of the Przewalski’s horse remain a mystery.
Why Did Horses Lose Their Toes?
While we don’t tend to think of it that way, horses literally walk on a single toe. Alongside donkeys and zebras, they are the only species on Earth to do so, and they have been this way for millions of years.
As their habitat changed from forests to grasslands, horses lost their toes so they could run away from predators faster. By decreasing the surface on which the horse touched the ground, a single toe greatly increased its running speed.
However, horses didn’t always walk on just one toe. Their earliest known ancestor, the Eohippus, had four toes on the front legs and three on the rear legs. The Mesohippus, which appeared around 40 million years ago, only had three toes on all feet. The middle digit, however, was already prominent.
Fast forward to 15 million years ago, and the Merychippus only stood on a central toe. Although this species still had two toes on each side, they only touched the ground while running. A close ancestor of the modern horse, the Pliohippus, already walked and ran on a single toe 8 million years ago.
Although the modern horse does seem to have lost all its toes, this is not the case. The long and narrow splint bones on the horse’s front and rear legs actually represent the second and fourth toes.
Scientists have also identified the first and fifth digits as the ridges on each splint bone’s end.
When Were Horses First Domesticated?
Until recent years, horse domestication was a hotly debated topic among scientists. There were two competing theories about this historical event.
The first theory stated that horses underwent domestication simultaneously across many locations, while the other pointed at the western Eurasian steppes.
A 2012 study revealed that horses were first domesticated by the Botai people in Kazakhstan around 6,000 years ago. Scientists believe they used the animals for meat, milk, and riding.
The study was conducted by a team of researchers at Cambridge University. First, the scientists took samples of the nuclear DNA of 300 horses living in eight different Eurasian countries. They then input the data into computers which created models for various domestication scenarios.
Lead scientist Vera Warmuth from the Department of Zoology said: “It shows that horse domestication originated in the western part of the Steppes and that the spread of domestication involved lots of integration of wild horses.”
Why Did Horses Become Domesticated?
Some experts believe domestication saved horses from going extinct like mammoths and other Ice Age megafauna. But what was it about horses that stopped humans from hunting them to extinction?
Horses first became domesticated most likely for their meat and milk. Later, as humans discovered their use in traveling, agriculture, and warfare, they began breeding horses for riding and driving.
In the early days of domestication, horses were probably kept as livestock just like cattle are today. At some point, however, people began keeping them as pets and realized they could be put to work. Many believe this holds the key to the horse’s transition from livestock to a riding and driving animal.
Horses also fit the six criteria of livestock domestication, which is crucial for the process to begin. These are:
- An efficient diet (e.g. able to survive on grass)
- A quick growth rate
- An ability to breed in captivity
- A pleasant temperament
- A tendency to not panic
- An ideal social structure
Being herd animals, horses have a dominance hierarchy that humans can easily take over. What’s more, they are also less territorial than many other species, which eased their way into domestication.
When Were the First Horses Ridden?
Although we don’t know if horses were first ridden or driven, riding most likely occurred first. Experts believe that the Botai people started riding horses as early as 6,000 years ago.
The truth is, it’s difficult to find evidence that shows when people first started riding horses. Scientists usually look at the wear on teeth and bits when trying to pinpoint the event. However, since horses can be ridden without a bit, these results are largely inconclusive.
Driving, on the other hand, leaves much more obvious clues. Scientists determined that horses were used to pull chariots for warfare fairly early. Still, there is plenty of indirect evidence to suggest that riding happened before.