What if horses had made it to North America?

Over millions of years, ancient horses roamed the North American continent. Then, many, many years later, horses played an important part in laying the groundwork for the United States. Yet, horses disappeared from the continent for an unexplained cause at one point in time.

Equus simplicidens, also known as the Hagerman horse, Hagerman zebra, and American zebra, is the genus Equus’ oldest-known species, appearing about 4 million years ago. It could be found from present-day Florida to Idaho. It resembled the current horse in appearance, having almost the same size with comparable teeth, a long face and neck, and completely fused limb bones. These early Equus species did not remain limited to North America; they were so successful that they spread outside the continent. They first migrated into South America and later spread into Asia, Europe, and Africa.

But, by the conclusion of the Pleistocene epoch around 10,000 years ago, most of North America’s big animals, including Equus species, were extinct. The cause of their extinction is widely debated among the scientific community with a definitive conclusion not yet determined, but several theories exist.

The fossil of Equus simplicidens may be found in the Utah Museum of Natural History in Salt Lake City, Utah.

“We know less about what caused the extinction of American horses 10,000 years ago than we do about what caused the extinction of dinosaurs 66 million years ago,” Eric Bendick, writer and producer of NATURE’s American Horses, told NATURE.

Climate change, human arrival, grassland vegetation development, or extraterrestrial influence are all conceivable causes. The end of the Pleistocene, or last ice age, most certainly resulted in a series of significant changes to the continent’s ecosystem and plant patterns. Around this period, bison populations started to expand and spread, competing with horses for food and producing a resource crisis. Fossil records from this time indicate that horses’ ranges were shrinking, and horses themselves were also shrinking in size, likely due to an inadequate food supply. Further pressure was placed on horses when humans arrived, as there is evidence suggesting that these early humans hunted horses.

“The majority of the dispute for all of the ideas revolves around the advent of humans to North America and whether human overkill was directly responsible for their demise,” Bendick said. “If humans were the major cause of extinction, the return of Equids might be considered a “rewilding” or “reintroduction” of a native species rather than as an exotic, feral, or invasive species on the landscape.”

Bendick has filmed a broad range of North American animals, including massive bison herds, fast groups of pronghorn, and thunderous elk. With his experience, he wonders how these other ungulates survived this extinction period while horses did not.

“Horses are tremendously quick, strong, and clever creatures. They can adapt to very hard and extreme environments like as drought, cold, and heat. For all of these reasons, human hunting is unlikely to have resulted in their demise – particularly because similar game species survived. Climate change and vegetation shifts seem to be more persuasive. Nonetheless, my suspicion is that a clear reason exists. “We’ve simply not discovered it yet,” Bendick said.

According to Bendick, scientists are still studying this phenomena, and fresh research is revealing new findings in this sector.

A white wild Mustang travels across a flower field in the highlands at night. Montana’s Pryor Mountains. (Photo credit: Jeff Reed / The WNET Group and TMFS GmbH)

When horses in North America became extinct, those that went out of the continent survived and flourished. Humans in other areas of the world started to recognize the use of horses around 4,000 years after North American horses vanished. Horses were employed for everything from hunting and agriculture to combat and transportation, and they started to impact human history. And in turn, humans shaped horses by selectively breeding them to grow larger and faster.

Spanish conquistadors introduced European horses to North America in the late 1400s, returning them to their natural habitat. During the time, North America was mostly covered in open grasslands, which provided an ideal home for these horses. These horses adapted swiftly to their old habitat and dispersed over the country. Around 1550, the first known feral horses escaped Mexico City, and more followed over time. Native Americans began to capture and ride the horses, spreading them further across the continent.

Horses have become one of the most common and ubiquitous creatures in the five centuries since their introduction to North America. The Spanish horses were the first to spread throughout the country, earning the name Mustangs. The Morgan horse grew to prominence on the opposite side of the continent when the Mustangs went wild out West. Other breeds like the Appaloosa and the American Quarter Horse also became popular among other communities. The United States is now home to over a hundred registered breeds, the greatest variety of Equidae in the world.

Further information regarding the history of horses in North America may be found in NATURE’s “American Horses,” the PBS Eons YouTube film “How Horses Took Over North America, Twice,” and Wendy Williams’ book “The Horse.”

Related Questions

• Were horses ever native to North America?

  Over millions of years, ancient horses roamed the North American continent. Then, many, many years later, horses played an important part in laying the groundwork for the United States. Yet, horses disappeared from the continent for an unexplained cause at one point in time.

• Why are horses not native to North America?

  The horses seen in the American West today are descended from a domesticated breed introduced from Europe, and are therefore a non-native species and not indigenous. Despite the fact that several horse lineages emerged in North America, they became extinct about 11,400 years ago during the Pleistocene epoch.

• When were the last horses here in North America?

  Although the genus Equus, of which the horse is a part, developed in North America, these horse ancestors became extinct about 8,000-12,000 years ago.

• Why did ancient horse go extinct in North America?

  Researchers looked at two of the most prevalent huge mammals that lived in what is now Alaska between 12,000 and 40,000 years ago: horses and steppe bison, both of which became extinct owing to climatic change, human hunting, or a combination of the two.