Are horses native to North America? The answer to this question is more complicated than you might think. You may have heard that the Spaniards first brought domesticated horses to North America in the late 15th century, but did you know that the first horses actually evolved in North America? Keep reading to learn more about the evolutionary history of horses in North America.
The Evolution of Horses in North America
The first horses evolved in what is now North America millions of years ago. Scientists believe these early horses eventually migrated to Asia via the Bering Strait. After that, it is believed that they breed throughout Asia and eventually came to Europe, North Africa, and the Middle East.
But if all this happened millions of years ago, how can we be sure that horses originated in North America? The answer lies in the fossils found on the continent.
The first ancestral horse family is believed to have originated around 56 million years ago. This period is known as the Eocene Age. During the Eocene Epoch, a species called Eohippus appeared. These early horse predecessors had hooves like the horses we know today, but they were much smaller than about 5 hands, or about 1.6 feet in height. The horses we know today averaged 15.2 hands, or about 5 feet tall.
Eohippus fossils have been found in both Europe and North America, but its relationship to modern horses is not always clear because Eohippus was very different from modern horses. However, additional fossils of now-extinct horses provide paleontologists with clues about the true evolutionary history of modern horses.
Orohippus is an ancestral genus of early horses that developed in the late Eocene Epoch. They are similar to Eohippus in size and structure, but there are distinct tooth differences between species. Orohippus’ premolars and molars are much more similar in size than Eohippus’s, which represents an evolutionary change that accommodates a more specialized diet. The tooth changes in Orohippus were later preserved in the species that would become the ancestors of today’s horses.
Mesohippus fossils found in North America are thought to date to the Oligocene Age, which began about 34 million years ago. Although Mesohippus was small with 6 arms, this species was much more similar to modern horses than its predecessors. Its brain is larger, its snout is more similar to its snout, and its legs are longer than those of previous species.
Eventually, Mesohippus evolved into a species known as Miohippus, whose descendants formed a distinct evolutionary branch. We know that one branch of evolution, known as Anchitheres, migrated from North America to Eurasia.
Parahippus, another descendant of Mesohippus, would be the direct ancestor of the modern horse. Parahippus, which has strong teeth and jaws that are able to move left and right, have adapted to eat grass. Parahippus is the direct ancestor of Merychippus, a species which, in 10 hands, is quite large compared to its ancestors. Merychippus, in turn, was the ancestor of Pliohippus. Pliohippus had one toe as opposed to its three-fingered ancestor. Its fossils can be found in bedrock from the Pliocene Age, which began about 5.3 million years ago.
Finally, Equus evolved from Pliohippus about 4 million years ago. Horses and other horses such as zebras belong to the genus Equus. There is evidence to suggest that they existed throughout North and South America during the Pleistocene Epoch, which began about 2.6 million years ago, but they began to disappear from this part of the world about 10,000 years ago.
Scientists can only speculate as to why these ancient horses disappeared from their North American homeland, but they believe that an influx of disease—perhaps by humans—may have killed many of them. Whatever the reason, one thing is certain: there were no horses in America by the time the Spanish arrived thousands of years later.
In conclusion, horses actually came from America. However, several thousand years separated the departure of the last real horse and the arrival of the first domesticated horse. The practice of domesticating horses, of course, did not begin in America; Horses are thought to have been first domesticated in the Eurasian Steppes nearly 6,000 years ago. We can thank Spain for reintroducing horses to the American economy and culture.
Featured Image Credit: kudybadorota, Pixabay