I think that's well established. I've dug for fossils of an extinct miniature horse, Plesippus shoshonensis gidley, in the Hagerman Fossil Beds in southwest Idaho. The Hagerman Horse has the distinction of being the earliest record of Equus, the genus that includes all modern horses, donkeys, and zebras.
It's odd to find this thread right now. I'm re-reading DeVoto's edition of Lewis & Clark's journals and got to wondering how the Nez Perce became master horse-breeders so quickly after the horse's reintroduction to America. The Appaloosa breed (aka Palouse War Horse) was legendary in Idaho where I grew up.
It was interesting to read Lewis & Clark's praise about them. I agree there doesn't seem to be any hard evidence as yet that any such horses preceded Columbus. But I think there's some logic to the argument they came from an area where pre-Columbian contacts with Asia, if any, were likely to have occurred. But one has to ask: why the Nez Perce, a mountain tribe, and not aboriginals closer to the Pacific coast?
The best estimate is that the horse was reintroduced to North America by Coronado's expeditions in the middle of the 1500's. The Lewis And Clark expedition was made in 1804. That's about 250 years for the Nez Perce to acquire the horse and become master horse breeders. Moreover, the introduction of the horse to the Nez Perce was at least as great a technological advancement as the introduction of the automobile in the last century. Do you also wonder how modern North Americans became master car builders so quickly after the automobile's introduction to America?
For a resource as revolutionary useful as the horse, two and a half centuries is more than enough time for a people to learn how to fully exploit it and then forget there was ever a time when they didn't have it. Especially when you consider that they preserved their history primarily orally, and the Spaniard's other gift to North America, smallpox, was incredibly effective at wiping out the older generations and their memories just as they were coming into contact with the horse for the first time.
Or, put another way, given the choice between spending my time hoping a buffalo herd wanders close enough to a cliff for me to stampede enough over it to make enough pemmican to survive the coming winter or just using a horse to follow the herds and run down individual buffalo as needed, I'd sure be spending my time learning how to ride and breed horses.
why the Nez Perce, a mountain tribe, and not aboriginals closer to the Pacific coast?Yes, why them, who had no contact with the Spanish? ;') The tribes moved around, though, so it's tough to point to points of origin.
Recent DNA tests on Appaloosas have revealed that the bloodline is majority Iberian horse (horses brought over by the Spanish) with DNA from Russian horses - the two stallions from Russia (I don't recall the name and can't look it up here at work) and some DNA from German and Belgium horses I believe (that would have have been circus horses brought over to the states in the 1800's)
Just a FWIW :)