continuous from Scandinavia to Greenland, this assumption seems justified. Yet, the problem is far from simple. The situation in the Old World is complicated by the presence of horse culture which appears as an early development and by the domestication of the reindeer. Either or both could have greatly stimulated dog traction, but on the other hand, dog traction could have developed in America and spread into Siberia. That it came in with the earliest Asiatic settlers is improbable, since in that case, though not necessarily, we should expect to find it surviving in southern South America. It is also true that the method of hitching in America is different from that in Siberia and contiguous parts of Alaska, and that nothing like the travois is found there.
Returning to our subject, we see that the prevailing mode of land transport in the New World was by human carrier. The wheel was unknown in pre-Columbian times. The wild fauna afforded nothing like the horse and ox of the Old World. The caribou has been found far less suitable for domestication than the closely allied reindeer, and the bison has proved itself rather too strenuous. Yet, these are not sufficient excuses. The plain fact is that the tribes in contact with these animals were relatively primitive. It is fair to assume that if the bison and the caribou had been available to the Peruvians, the tale would be different.
Before the time of Columbus, no tribe had an animal able to carry a man. The dog packers walked in front of their trains, and even the Eskimo walked more than they rode. The coming of the Spaniards made quick changes. The mule and donkey were soon in general use in the area of intense maize culture, though they have not yet entirely displaced the llama in Peru. Wild cattle soon overran Texas and southern California and in the Pampas became almost as numerous as the bison in the North. Their presence greatly modified the food supply, but the most far-reaching change resulted from the spread of the horse.
By direct instruction or mere self-initiated imitation, the natives of the bison and guanaco areas acquired horse culture. Unfortunately, the history of this cultural acquisition is lost,
