By Ross MacPhee, PhD, Curator - Division of Vertebrate Zoology, American Museum of Natural History, New York, NY
A "native" species, in evolutionary terms, is defined as one that differentiated or diverged from its immediate ancestor species within a specific geographical locale. The contemporary wild horse in the United States is recently derived from lines domesticated in Europe and Asia. But those lines themselves go much further back in time, and converge on populations that lived in North America during the latter part of the Pleistocene (2.5M to 10k years ago).
The morphological (fossil) evidence and the more recent DNA evidence (although preliminary), points to the same conclusion: the species Equus caballus—the species encompassing all domestic horses and their wild progenitors—arose on this continent.
Horses may have survived in North America until 7600 years ago, some 5000 years longer than previously thought. It is possible researchers have unearthed the tiny genetic footprint of the last few hundred ancient horses to roam North America.
Researchers who removed ancient DNA of horses and mammoths from permanently frozen soil in central Alaskan permafrost dated the material at between 7600 and 10,500 years old.
The findings suggest populations of these now-extinct mammals endured longer in the continental interior of North America, challenging the conventional view that these and other large species disappeared from the continent about 12,000 years ago.
Statement for the 109th Congress (1st Session) in support of H.R. 297
A Bill in the House of Representatives
House Committee on Resources
Introduced January 25, 2005
To restore the prohibition on the commercial sale and slaughter of wild free-roaming horses and burros.
By Jay F. Kirkpatrick, Ph.D. and Patricia M. Fazio, Ph.D.
Are wild horses truly “wild,” as an indigenous species in North America, or are they “feral” weeds – barnyard escapees, far removed genetically from their prehistoric ancestors? The question at hand is, therefore, whether or not modern horses, Equus caballus, should be considered native wildlife.