Fact Checker: Mustangs - Return of the Native or Invasive Species?
FRANK MULLEN • FACTCHECKER@RGJ.COM • NOVEMBER 23, 2010
THE CLAIMS
1) Wild horses didn't become extinct in North America and remnants of the ancient herds were still present in this hemisphere when Columbus landed in the New World in 1492.
2) Mustangs on public lands are a feral, invasive species, introduced into an environment where they are not native and should not be allowed to roam.
THE BACKGROUND
The two claims are at opposite extremes of an ongoing debate that surrounds the federal government's wild horse roundups in the West.
It's generally accepted that horse species evolved on the North American continent. The fossil record for equine-like species goes back nearly 4 million years. Modern horses evolved in North America about 1.7 million years ago, according to researchers at Uppsala University, who studied equine DNA. Scientists say North American horses died out between 13,000 and 10,000 years ago, at the end of the Pleistocene Epoch, after the species had spread to Asia, Europe, and Africa.
Horses were reintroduced by the Spanish explorers in the 16th century. Animals that subsequently escaped or were let loose from human captivity are the ancestors of the wild herds that roam public lands today.
That's the theory, but revisionists point out that some sources, including the Book of Mormon and Native American cultural tradition, say horses have been continually present on the continent long after the last Ice Age. Some folks contend the original Appaloosa horses of the Nez Perce tribe, which were distinct from other horses, were a remnant of the original equines of the Americas.
Over the years, the horse extinction theory has changed.
Many scientists once thought horses died out on the continent before the arrival of the ancestors of the American Indians, but archeologists have found equine and human bones together at sites dating back to more than 10,000 years ago. The horse bones had butchering marks, indicating the animals were eaten by people, according to "Horses and Humans: The Evolution of Human-Equine Relationships," edited by Sandra L. Olsen.
So it appears that humans and horses coexisted in the New World prior to 1492, but did they continue to survive in North America over the last 100 centuries?
The claim that wild horses in America are as invasive as Asian clams in Lake Tahoe or rabbits in Australia also is made in the wild horse management debate. Some ranchers call mustangs "long-legged rats" and reader comments on RGJ stories about roundups always include opinions that the mustangs are feral interlopers and should be dealt with as vermin.
Federal law makes the argument academic.
In 1971, Congress declared wild horses and burros to be "living symbols of the historic and pioneer spirit of the West; (and) that they contribute to the diversity of life forms within the nation and enrich the lives of the American people."
Lawmakers unanimously decided the free-roaming equines be "protected from capture, branding, harassment, or death, and to accomplish this they are to be considered in the area where presently found as an integral part of the natural system of public land."
Federal officials are charged with managing the free-roaming herds to achieve an ecological balance, and disagreements about the wisdom and quality of that management is the source of current debates.
THE VERDICT
By definition, horses are North American natives because most of their evolutionary development took place on this continent. They are "native" rather than "livestock-gone-loose," because they originated here and co-evolved with the American habitat, according to Jay F. Kirkpatrick, director of the Science and Conservation Center in Billings, Mont.
DNA research by molecular biologist Ann Forsten of Uppsala University concludes the ancient horses and the modern domestic horses are the same species. That finding contradicts critics who maintain the original North American horses and the ones that were reintroduced aren't the same animals.
No one is certain why, at the end of the last Ice Age, equines vanished from the hemisphere. Theories of the cause of the extinction include drought, disease, or a result of hunting by humans.
The submergence of the Bering land bridge prevented any return migration from Asia. There's no proof any horses escaped extinction in the Americas. If horses survived in the New World up to the 15th century, then no one has ever been able to find the physical evidence to prove the theory.
But, as horse advocates maintain, modern horses evolved here and that's an adequate reason to consider them native American species, and not "invasive" or "introduced feral animals."
The horses were "reintroduced" to the continent, unlike the Asian clams in Tahoe or the rabbits of Australia, which were inserted into regions where Nature never put them and where they could disrupt the ecological balance.
Truth Meter: 1 Given what we know about the history and evolution of horses in North America, both claims are false.
