Unless a fellow can swim he has no business to go out of his depth; but if he minds his business, he loses all the fun.
It is the application of these two principles which leads me to a problem in the history of the horse which nobody has solved.
The species is native to the Americas, where it became extinct. One theory of this extinction imagines a germ, like that of horse-sickness, whose range covered all latitudes from tropic to sub-arctic. Such a hearty microbe as that would seem unusual.
The other theory relates to a disagreeable change in the climate, which overwhelmed the drainage basin of the North Atlantic with a field of massive ice. That seems conclusive until one reflects that the Pacific slope of the United States and the continent of South America remained as warm as ever. The cold of the Great Ice Age does not explain the wiping out even in North America of the camel, elephant, tapir and horse.
The Ice Age
It has been my good fortune to make a series of voyages to Bering Sea and Norway in the winter, and in summer along the flanks of both the St. Elias and the Greenland ice-caps. In these journeys by sail and steam, in boats, in canoes, with many landings and scrambles across county, I was able to test the theories of Glacialogists against the actual facts of the Great Ice Age.
The Croll theory makes the orbit of the Earth to change at regular intervals into a long ellipse. By roasting one entire hemisphere it provides vapour to cover the whole of the other hemisphere with snows which do not melt. Evidence is scratched up and made the most of for previous ice ages. An imaginary series of cosmic cataclysms is invoked to explain one merely local unpleasantness.
Another theory sinks Central America—politically quite a good idea—and throws the Gulf Stream into the Pacific, leaving the North Atlantic to be frozen. It does not explain the American lobe of the icefield which brushed the foothills of the Rocky Mountains in a region outside the influence of the Gulf Stream.
It was never the business of Glacialogists to notice that under the inland ice and the great lava floods of Greenland lie pressed magnolia leaves in the high Arctic. These tell me of cloudy skies saving the summer's warmth all through the polar night, of a vast cloud sphere sheltering the whole Earth from a sun much hotter than we know to-day. The Ice Age to me is an incident in that clearing of the skies which dried the world-forest, made the grass steppes and deserts, and evolved the horse.