By Janice M. Ladendorf

Scientists still agree that the equine species evolved on the prairies of North America. About four million years ago, the common ancestor of the horse, zebra, and donkey roamed the grasslands of North America. Why the true horse evolved here and not elsewhere remains a mystery. Skeletons of some of the various species that eventually evolved into Equus caballus have been found in South America, but real horses did not reach there until they were brought by the Spanish. Similar types of skeletons have been found in Europe, but skeletons of Equus caballus did not occur there until after horses had begun migrating across the Bering Strait.

Whenever enough water was locked up in glaciers, horses and other animals could travel between North America and Eurasia over a land bridge in the Bering Strait. Beginning two or three million years ago, scientists believe many migrations between the continents occurred. These migrations went both directions, some from Alaska to Siberia and some from Siberia to Alaska. This bridge was once part of Beringia, a grassland steppe covering 620,000 square miles which extended deep into both Siberia and Canada. Herds of horses would have found excellent grazing there.

The Pleistocene Park in northern Siberia is an attempt to recreate the ecological system which once existed in Beringia. One of their first steps was to select Yakut horses as the representative equines for the park. When they were turned loose in the park, some died because they could not tolerate the severe winters and others because they ate poisonous plants. Those who were left thrived and changed their environment. Mosses, weeds, and willow shrub have disappeared and they now graze on the grasslands they created.

yakutian horses1
Yakut Horses in Pleistocene Park

The Great Pleistocene Extinction

Between 11,000 and 13,000 years ago, climatic changes may have driven the horses out of North America. At the same time, other species of big herbivores and the carnivores that preyed on them also disappeared and many are now extinct. Horses are born survivors. Their remote ancestors survived the dinosaur extinction and by 35,000 B.C. fossil evidence indicates Equus caballus was already widely distributed on the Eurasian steps. After 10,000 B.C., Equus caballus disappeared from some, but not all areas. The survivors managed to adapt to the climatic change and were the ancestors of our modern horses.

Yakut horses
Yakut Horses in Pleistocene Park

DNA analysis has confirmed that all modern horses descend from the small, stocky wild horses who once lived on our prairies. Although we often use the names of modern countries to describe various breeds of horses, their remote ancestors initially came from North America. Like all other breeds of horses, the ancestors of the Spanish horse originally came from here. In the 16th century, when the conquistadors brought horses to the New World, they returned them to their original home where they fit right back into an already established ecological niche.

American mustangs are horses who have escaped from captivity and their feral status gives them little protection under our current laws. The government administrators who manage the remaining wild horse populations define them as an exotic species instead of one of our more illustrious native species. They also claim they destroy the environment, but conservation biologists believe they are one of the keystone species in the restoration of damaged grassland ecologies. What happened in Pleistocene Park is a good example of the favorable impact horses can have on their environment.

Did Equus caballus ever completely disappear from North America? 

a) Did remnants of the original wild horse survive here?

Considerable controversy exists over whether or not any members of the original species of wild horse survived here as did the remnant herds in Eurasia. Opponents of the extinction theory base their views on what many scientists still regard as dubious evidence. One type of evidence comes from controversial human interpretations of various petroglyphs or geoglyphs. Another type comes from the analysis of a few examples of fossil bones, but scientists have questioned the accuracy of the methods used to date these bones. The last type rests on various exploded historical theories or unproven myths.

One such exploded theory came from the observations of a Buddhist monk named Hui Shen. In 500 A.D., he described a country he called Fusang which lay to the east of China. The inhabitants had horses, carts, and domesticated deer. In Eurasia, reindeer were domesticated long before horses. In the nineteenth century, many assumed Hui Shen had described a site in North America, but it has now been identified as the Buriat region of Siberia.

b) Could horses have been brought here by those who discovered America before Columbus?

Even if the extinction theory is correct; some have argued horses could have been brought here by those who discovered America well before the arrival of Columbus. Some of the Plains tribes do have legends stating they “always” had horses, but how far back “always” goes has yet to be defined in European calendar years. Wild horses are not particularly well suited to life in heavily forested areas. By the time most of these tribes moved out onto the prairies, Spanish horses had already reached their new hunting grounds. Without horses, these tribes could not have found and killed enough buffalo to support their population.

There is some evidence various groups of humans came here, but none to prove the discoverers brought horses with them. Exponents of this theory tend to overlook the limitations imposed by the available shipping technology and the quantity of food and water needed by horses on long ocean voyages. When Iberian horses were shipped here in the 16th century, over 50 percent died on the perilous journey.

The Norwegian Vikings explored the Canadian coast and what they called Vinland from their colony in Greenland. They brought horses with them to Iceland and a few further on to Greenland. Some believe they also took them to North America, but there is no evidence to support this belief. Cattle bones have been found at one site in Canada, but no equine bones.

Another myth concerned early Welsh settlers and is based on the legend of Prince Madoc or Madog, but there is no conclusive archeological evidence to show this man and his followers ever reached any site in North or South America. This story may have begun as a medieval romance, but it was used to support early British claims to the New World. In later centuries, the story was expanded by claiming the Welsh settlers had intermarried with various Indian tribes, but the lack of genetic evidence has turned this myth into another exploded theory.

Some evidence suggests the Chinese may have established a few settlements on our western coast. If they brought a few horses with them, their presence could explain the resemblance between Mongolian or Chinese horses and Indian ponies, but there is another more likely explanation. Horses from Mongolia and China are small and stocky. Like zebras, their conformation gives them the ability to swiftly spin around and kick threatening predators. They are thought to resemble the Steppe pony or the original wild horse. When any domesticated species goes wild, it eventually reverts back to the original type best suited to survival in the wild. The Spanish imported different types of horses and by the time those who escaped reached the Plains Indians, they could have been well along the way in the reversion process.

Przewalski’s horse (Equus caballus Przewalski) has also been compared to Indian ponies, but this comparison is not a valid one. For many years, this species had been thought to represent the original wild horse and this idea may explain why some still believe modern horses are exotic because they evolved from the original wild horse. Modern scientific research has exploded this theory. Przewalski’s horse split off from Equus caballus about 50,000 years ago and stayed in Mongolia. Before humans killed all of them, in the 19th century a few were captured for zoos and they have been used to reintroduce their species into their original homeland.

Some similarities in the saddles and bows used by the Mongols and the Plains Indians have also been identified. Because all saddles must fit equine conformation and movement, they must have certain features, like the saddle tree, in common. Mongol saddles were designed for warriors while Indian saddles were mainly used by women. Mongols and Indians both used short, laminated recurve bows on horseback, but both groups used more than one type of bow and used different native materials. Even if the Chinese settlers brought no horses with them, they could have brought bows with them or the ones used by the Plains Indians could have been a case of simultaneous invention.


Those who argue against the extinction theory and for horses brought by early visitors have overlooked one basic biological law. When members of any wild species are exposed to an optimum environment, their population expands rapidly until it reaches the maximum that environment can support. This rule applied to both wild and feral animals. Populations can expand and shrink with climatic changes. With the original wild horse, the last such changes in population size occurred here about 25,000 B.C.

An explosive expansion is what happened when the Spanish horses hit the optimum environments of our prairies and the Argentine pampas. Our southeastern states had a less optimum environment. There the Indian ponies and feral horses came with the early Spanish missions. These settlements followed the Gulf Ladendorf aug 16 300x250Coast to Florida, then up the East Coast as far as Virginia. The feral horse population did not expand as rapidly there as it did on the prairies.

Why didn’t the populations of remnant horses or early equine immigrants expand as their ancestors had? Could remnant horses have been trapped by natural barriers and found by Indian hunters? In Eurasia horses were not domesticated until about 6,000 B.C. Could the Indians have domesticated the remnant horses? There is no evidence to support this possibility. When the Spanish came with their horses, they soon began turning Indians into expert riders. The Indians who did not learn from the Spanish could well have learned from other Indians.

Immigrant horses would have been domestic and their population could have been controlled by man-made barriers. The problem with this solution is that fencing is both expensive and labor-intensive. For thousands of years domestic horses often had to be turned loose to feed themselves by grazing. The Dutch were the first to use barns to house their animals and feed them through the winter. Even today, Mongol herds are never confined but simply follow the migrations of their nomadic masters.

The Equine Ecological Niche

At this time, the arguments against extinction and for early equine emigrants appear to be biased by the emotional views of mustang advocates and their search for any evidence, however dubious, to prove mustangs are a native species because they have always lived here. Whether or not they were extinct in North America is irrelevant. DNA analysis has already established all modern horses descended from the original wild horses of North America. A species is only extinct when there are no fertile individuals left alive. Millions of years of evolution had created an ecological niche for the original wild horses. When the Spanish brought horses back to their original home, they so quickly adapted to their new environment because they stepped back into their own original ecological niche.

Over two million years, evolution had given horses the functionality to adapt to an incredible variety of physical environments. Horses grow two hair coats a year, one for hot summers and one for cold winters. External temperatures will adjust both hair length and density to the optimum for survival. Their natural speed and endurance allows them to graze three day’s travel from their nearest source of water.  The longer and heavier their manes and tails, the more able they are to protect themselves from flies. Their teeth and prehensile upper lips give them the ability to crop grass down to the right height to promote maximum growth.

Evolution also programmed them at the instinctive level for a variety of survival oriented behaviors. Horses are powerful enough to break trails through heavy brush. Unlike cattle, in the winter they will eat snow as an alternative to water and use their hard hooves to paw through snow to reach the grass underneath. Some of what they have to do to survive aids other species. In winters, they smash through the ice on waterholes to get water to drink. In summers, they dig for both water and salt. What they open up other animals can use to survive.

The keen noses of wild horses allow them to find every source of water in their territories. Their instincts tell them predators lurk around waterholes so they do not hang around them. Some herd members always stand guard while others drink. Wild herds will roam around their territories to find optimal living conditions for each season of the year. They often have summer and winter pastures. To avoid flies in summer, they may move to higher altitudes where they can find cooler weather and hilltops where winds will blow insects away from them. In winter, they move to ground where they can find shelter from blizzards and windswept ridges with exposed grasses. Older members of the herd remember when and where the best seasonal grasses grow. At any time of the year, the lead mare will take her herd to where they can find the best grazing.

Wild horse digging for water on Sable Island.
Wild horse digging for water on Sable Island.
Shackleford horse digging for water.
Wild horse digging for water on Shackleford Banks

The Equine Ecological Impact

Their favorable impact on the ecology comes from a combination of their roaming habits and their unusual digestive systems. Their systems are relatively inefficient so they must eat a high quantity of food to satisfy their nutritional needs. Horses prefer high quality grasses, like the gamma grasses our prairies once had, but evolution gave them the ability to survive on any type of grass, such as the low quality salt marsh grasses on Assateague Island. Wild horses will typically graze down lower quality grasses whose growth could otherwise feed forest fires. Horses are not just grazers; they are browsers who can digest plants, such as shrubs, leaves, shoots, and bark. They will even eat poison ivy and dandelions. In the winter, Indian ponies often survived because they could eat and digest Cottonwood bark.

The end result of their high quantity diet is lots of quality manure. It includes the seeds of whatever wild plants they are eating and it enhances soil fertility because it contains a high level of nitrogen. As wild horses roam, they deposit manure all over their territories and it encourages the growth of vegetation. Some research has discovered horse grazed sites show better grass cover and species richness. When they are fenced or held by humans in too small an area, they can damage their environment. So far, there is no proof free-roaming horses have ever damaged the ecology of their environment. On the contrary, if they are allowed to roam freely in enough space, they will enhance their environment. This fact has been well established in Eurasia, but ignored in North America.

The Feral Horses of Sable Island

Since 1961, Canadian law has protected these horses, and in 2011 Sable Island finally became a true nature preserve. Despite the lack of predators and non-interference by humans, the population of these horses remained relatively stable for many years. Recently it has increased, but the horses continue to thrive. No research has been reported as to why this has happened. Like the Yakut ponies, they may have improved their environment so it can carry more horses. Their interesting story is told in an article published in Valley Equestrian News on May 17, 2016.

The Equine Impact on Ecosystems in Europe

Conservation biologists have classified equines as one of the keystone species which is critically important in the regeneration of the Earth. Scientists believe evolution gave horses the ability to modify their environment to suit their species and in doing so, they will benefit numerous plants and animals who share their ecosystem. Rewilding, or species reintroduction, is increasingly being seen as a valuable tool for saving species from extinction and for reintroducing locally extinct species.

Sable horses
The feral horses of Sable Island

There are various reasons why certain breeds of small horses or ponies have been selected for reintroduction. Konik horses are a re-creation of one of the original types of wild horses. Many of the English pony breeds are semi-feral because they are allowed to roam freely on common pastures or preserves. As compared to most pampered domestic breeds, these ponies are more resistant to harsh weather and severe winter conditions. They are still adapted to foraging in the wild and capable of digesting coarse grasses and shrubs, as well as adjusting their diet according to the season of the year and food availability. Our American mustangs have the same capabilities.

Konik Horses

The first reintroduction project began in the Netherlands in the Oostvaardersplassen, a famous wetland which had been reclaimed from the sea. In 1984, Konik horses, Heck cattle, and red deer were introduced there to control the emerging forests and to keep open the areas needed by migrating birds. The first twenty ponies thrived and their number now exceeds 1,000. They proved to be hardier than the Heck cattle. The Konik or Konig is the result of an attempt to recreate the tarpan, the Heck cattle is the result of a similar attempt to recreate the aurochs.

Konik horses of Oostvaardersplassen
Konik horses of Oostvaardersplassen

Other projects in England soon followed the one in the Netherlands. One of the few remaining pieces of undrained fen in East Anglia is Wicken Fen. The project there carefully followed The World Conservation Union guidelines for the protection of the environment against invasive species, as well as the appropriate government regulations. In 2003, tough, robust Konik ponies and Highland cattle were introduced there. At both Oostvaardersplassen and Wicken Fen, administrators believe the creation of optimal environments requires the use of multiple species.

The horses at Wicken Fen began by carefully investigating every inch of the new land. Soon they established paths along favored routes, and started grazing evenly around their new territory. They eat lush, sweet grasses in the spring and summer; then add rushes and sedges in the autumn and winter. They regularly browse on scrub and plants, such as nettle, thistle, and bramble.

Konik horses are currently being used to manage four nature preserves in Kent at Stodmarsh, Pegwell Bay, Whitehall Meadows, and Ham Fen. At Stodmarsh the Koniks are rotated regularly among areas of marsh and reed bed. At the other preserves, Konik horses have been put out to graze by farmers and they helped speed the conversion of marginal farmland to grassland. Numerous species have benefited from these changes, including ducks, geese, and meadow birds.

English Pony Breeds

The English may have begun with wetlands, but reintroduction soon spread to other types of terrain. In 1989, New Forest ponies were invited to graze on National Trust land in Hampshire, Wiltshire, and the Isle of Wight. Recently the town of New Milton invited six New Forest ponies to graze on Barton Common and put seven Dexter cattle out on Ballard Water Meadow. Experts expect to see a greater variety of dragonflies and hoverflies; as well as wetland and heathland plants. The town’s main goal was to improve the habitats for plants and wildlife; but in addition, they no longer had to pay to have the grass mechanically mowed.

Five New Forest Ponies on Barton Common
Five New Forest Ponies on Barton Common

One of the responsibilities of the Dartmoor Commoners Council is the ponies who graze on the moor. In recent years, their population has continued to decline and the Council was concerned about the ecological impact on the moor. They commissioned a study relevant to pony grazing on upland habitats. They found some general guidelines, but concluded they needed to know much more about the ecological interaction of the ponies, cattle, and sheep who graze on the moor.

dartmoor ponies at little mis tor WK
Dartmoor ponies at Little Mis Tor

Exmoor ponies have also turned out to be an excellent choice for conservation projects. They thrive on the low quality plants on chalk grassland and heathland because they are highly selective grazers who devour coarse grasses, gorse, rush, sedges, brambles, and even bracken. When they kept the grass short in Purbeck, Dorset, two rare species of orchids flowered once again. When they were released in the Quantock Hills in Somerset, violets returned to the tracks and the deer increased in number.

Much of the once rich and productive land now in the Czech Republic was badly damaged by the collectivization policies enforced from 1940-1989 by their communistic government. Environmentalists there have begun a large scale project to heal the land.  After careful investigation, they decided not to use Koniks because of geneological errors made by the breeders who created them so instead they decided on Exmoor ponies. Fourteen mares and a stallion have been shipped there from England. They were turned loose near Prague on land which had been barren for seventy years. The ponies have adapted well and numerous endangered plants and animals have started to return, much faster than the researchers expected.

The Netherlands proposes to turn 17 percent of their land into nature preserves. Their plans include the extension of preserves into Belgium and Germany.  The United Kingdom plans to continue turning marginal farming land into nature preserves. Tourism now accounts for ten per cent of the world’s GNP and ecotourism has been a significant part of this increase. The Welsh are already thinking of re-introducing beaver. Other species which may be re-introduced are wild horses, aurochs, elk, and reindeer.


For many years, there has been considerable controversy over the future of the feral horses who remain on public property in the United States. Those who want to preserve them have tried to prove they never disappeared completely. Those who want to exterminate them have had considerable success. They believe horses are an exotic species and damage the range environment, but horses did evolve here and free roaming horses will improve their environment for themselves and other species.

While our mustang population is declining rapidly, the wild horse population in Europe is increasing. Horses have been defined as one of the keystone species for the regeneration of the land. They have been used to enhance the ecology at nature preserves in Eurasia.

To find an optimal solution for our mustangs, my research suggests mustang advocates and those who administer the current management programs should investigate what conservation biologists have discovered and what has been accomplished and planned in other countries.

Information Resources:

Baumann, Deb. “Are Wild Horses Really Wild?” The Equestrian News, June 2006.

Beever, Erik. “Management implications of the ecology of free-roaming horses in semi-arid ecosystems of the western United States,” Wildlife Society Bulletin vol. 31, 2003, pp. 877-895.

Downer, Craig. The Wild Horse Conspiracy, 2011. pp. 1-49.

Forder, Victoria. Conservation Grazing: Konik Horse, European Beaver, and Wild Boar, Wildwood Trust, August 2006.

Fraser, Caroline. Rewilding the World: Dispatches from the Conservation Revolution. NY, Henry Holt, 2009.

Gill, Elaine. “An ecological mowing machine,” Ponies in the Wild, 1994, p. 117.

Grayson, Donald K. “The Chronology of North American Late Pleistocene Extinctions,” Journal of Archaeological Science, 1989, 16, 153-165.

“Indian Horses BEFORE Columbus”, 2013,

Janis, Christine. “The Evolutionary Strategy of the Equida and the Origins of Rumen and Cecal Digestion,” Evolution, 30, Dec. 1976, pp. 757-774.

Kirkpatrick, Jay. “Chapter 2: The Horse as a Successful Wildlife Species,” Into the Wind, NorthWood Press, 1994, pp. 45-64.

Ladendorf, Janice. “A Lost Breed: The Chickasaw Horse,” Valley Equestrian News, July 2014, pp. 8-9.

Ladendorf, Janice. “The Feral Horses of Sable Island,” Valley Equestrian News, May 17, 2006.

Ladendorf, Janice. Chapters 9, 12, 15, 17, Spanish Horsemen and Horses in the New World, Create Space, 2015.

Laidlaw, Carol. “The Wicken Fen Vision: grazing an evolving landscape,” Conservation Land Management, Spring 2011, pp. 5-8.

Leste-Lasserre, Christa. “Exmoor Ponies Help Revamp the Czech Republic’s Landscape,” The Horse, Aug. 29, 2015.

Martin, Paul S. Twilight of the Mammoths, Univ. of California Press, 2005. p. 110.

“New Milton pony grazing will ‘save money’,” BBC News, 9-16-14.

Orlando, Ludovic. “Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene Horse,” Nature 499, July 4, 2012, pp. 74-8.

Simov, S.A. “Pleistocene park; return of the ‘mammoths’ ecosystem,” Science, 2005, vol.  308, pp. 796-98.

Quammen, David. “Return of a Native”, “People of the Horse, National Geographic, March, 2004. pp. 114-15.

“Upland Pony Grazing: A Review,” Dartmoor Commoners Council, 2016.

Vidal, John. “Wild herds may stampede across Britain under plan for huge reserves,” The Guardian, Oct. 27, 2005.

Vila, Carles. “Widespread Origins of Domestic Horse Lineages,” Science, Jan. 19, 2001, pp. 474-7.


Author’s Note: Look for my next article, “Mustang Mismanagement” in the Valley Equestrian News.