the gradual rise of
the continental areas, and a fall of temperature that ushered in the Ice
Age. With the death of tropical vegetation, the giant mammals passed
away.

THE HORSE AND HIS ANCESTORS

Every city has a horse market, where you may look over hundreds of
animals and select one of any colour, size, or kind. The least in size
and weight is the Shetland pony, which one man buys for his children to
drive or ride. Another man wants a long-legged, deep-chested hunter.
Another wants heavy draught-horses, with legs like great pillars under
them, and thick, muscular necks--horses weighing nearly a ton apiece and
able to draw the heaviest trucks. What a contrast between these slow but
powerful animals and the graceful, prancing racer with legs like
pipe-stems--fleet and agile, but not strong enough to draw a heavy load!

All these different breeds of horses have been developed since man
succeeded in capturing the wild horse and making it help him. Man
himself was still a savage, and he had to fight with wild beasts, as if
he were one of them, until he discovered that he could conquer them by
some power higher than physical strength. From this point on, human
intelligence has been the power that rules the lower animals. Its
gradual development is the story of the advance of civilization on the
earth. Through unknown thousands of years it has gone on, and it is not
yet finished.

[Illustration: _By permission of the American Museum of Natural History_

Restoration of a Siberian mammoth, _Elephas primogenius_, pursued by men
of the old stone age of Europe. Late Pleistocene epoch]

[Illustration: _By permission of the American Museum of Natural History_

Restoration of a small four-toed ancestor of the horse family, _Eohippus
venticolus_. Lower Eocene of Wyoming]

Just when and where and how our savage ancestors succeeded in taming the
wild horse of the plains and the forests of Europe or Asia is unknown.
Man first made friends with the wild sheep, which were probably more
docile than wild oxen and horses. We can imagine cold and hungry men
seeking shelter from storms in rocky hollows, where sheep were huddled.
How warm the woolly coats of these animals felt to their human
fellow-creatures crowded in with them in the dark!

It is believed that the primitive men who used stone axes as implements
and weapons, learned to use horses to aid them in their hunting, and in
their warfare with beasts and other men.