Science tells us that millions of years of evolution has put us, and all other animals, where we are today. They tell us that the fish grew legs to walk and lungs to breathe, gills disappeared and reformed creating the creatures they are today. Through all of the chaos in evolution, horses formed into the majestic animals they are today. The equine species is one of the most well studied, and best understood timelines that showcases the scientific understanding of species evolutionary facts and theories.
Continental Drift: Before and After the Earth Shifted
Not only were animals evolving through the years, but the earth was morphing with them. With better access to all parts of the earth, the early horses roamed many parts of the world. The modern rise to horses originated from Eurasia between 2 and 3 million years ago. Subsequently,
the previous North American population of early horses became extinct around 8,000 and 12,000 years ago.
In the 1970’s a group of archeologists discovered the remains of an early horse that they called the Eohippus. The term used to name the early horse is a Greek term that means “Dawn Horse” whereas a similar term of the word means a Hyrax-like Beast. A Hyrax being a small, furred creature, sometimes called a rock badger. The fossil was found to be around 56 million years old; when the Eohippus made their first appearances.
Eohippus: The First Equine Species
Though the Eohippus is considered to be where the modern day horse originated, the closest
extinct creature similar to the horses we have today, was the Tarpan horse. This horse was of Euarsian descent, superiourly evolving from the Eohippus due to the world placement drifting over the millions of years, separating the two descendants into vastly different environmental biomes, in two vastly different time frames after migrating.
Start of Evolution
The Tarpan horse was formed from a long evolution starting from the Eohippus and moving to the Orohippus, found around 2 million years after the Eohippus was roaming the earth.
The Orohippus, a direct descendant of the Eohippus, was around the same size as the previous species but had a longer neck, slimmer figure, and longer back legs which is a quality of a jumping animal. Unlike their predecessor, the Orohippus moved away from foraging in the forest environment and became a browser, feeding on rangeland areas. This species lasted around 20 million years and were followed by the Mesohippus.
Mesohippus lived around 35 million years ago and stood larger than the previous two species. It was around 6 hands tall, with slim, long legs and a muzzle like nose. The term meso indicates the term “middle” meaning it is the middle species between modern day horses and the early horses. The fossils of the Mesohippus were found in the plains of North America, concluding that the
equid species continued to use the land bridge between Eurasia and North America for millions of years to travel to different biomes, leaving multiple different evolved species in their wake.
Starting to Take Shape
The form of today’s horse begins to take shape in the Mesohippus, but still has quite a long way to change. After this is the Merychippus, which continued to grow in height and formed hooves instead of the previous toes it was accustomed to. This was the first equid species to show the modern day horse head shape featuring the deep jaw and long muzzle. The animal stood at the size of today’s average donkey breeds. Once again found in North America and suspected to have roamed from almost 17 million years ago to 5 million years ago.
Unlike the other species of equid having originated from the evolution and extinction of another, the Pliohippus formed while the Mesohippus was still roaming in North America. Around 15 million years ago, just 2 million years after the evolved Mesohippus appeared, the Pliohippus began to coexist with them in North America. Similarly to the early start, they became extinct just around 3 million years after the Mesohippus. While this is still a large and significant amount of time to pass, in comparison to the 20 million years that the Orohippus lived, it is a small window in time.
The Migration
The Pliohippus gave rise to the modern day horse, smaller in size but anatomically similar in a number of ways. With almost every major evolutionary point of the horse taking place in North America, how is it that they later had to be introduced back into North America from European and Spanish settlers?
The ice age around 2.5 million years ago forced the North American horses to move out of the environment that was rapidly becoming too cold for them to continue surviving in. While some moved south, others moved across the Beringia land bridge and fled to Eurasia. Evolution to survive the harsh winters they encountered took place, morphing into large, powerful creatures to overcome the unforgiving mountainous lands they crossed.
Digitally constructed image of early horses migrating away from North America
The more recent years saw more evolutionary changes. The fled horses were captured and domesticated by the Spanish and Europeans, later bringing them to the new land of America in 1493. This was Christopher Columbus’s second voyage to the new land, where he brought many more resources with him in order to begin settlement in the area. It was around this time that these horses started to be seen around North America again, after 11,170 years of distant evolution in Eurasia.
Todays Wild Horses
Whether it was adaptation or instinct passed down from their ancestors, the horses that escaped the grasps of the new settlers took to the lands of the new world quickly. Many hurds ran into the mountains for hundreds of years to preserve their bloodlines and protect their kin. To this day there are still wild mustangs protected by the people and hunted by the government, similar to the day they arrived in the new land.
States like Idaho, Montana, Nevada and Wyoming hold thousands of wild horses, fighting to stay hidden and protected. While protection groups speak in their favor, others speak against them stating that they are a nuisance to the land, much like a pest in a house. Cattlemen and ranchers work hand in hand with the governors of the state to ensure populations of the wild horses are kept under certain amounts. Though the look of the horse has changed drastically over the last 56 million years, their spirit is still, and always will be connected to the great North American plains.
