to the south stretched a bleak wilderness whose climate changed from harshness to a mild kindliness and then hardened again for the Fourth Glacial Age.
Across this wilderness, which is now the great plain of Europe, wandered a various fauna. At first there were hippopotami, rhinoceroses, mammoths, and elephants. The sabre-toothed tiger was diminishing towards extinction. Then, as the air chilled, the hippopotamus, and then other warmth-loving creatures, ceased to come so far north, and the sabre-toothed tiger disappeared altogether. The woolly mammoth, the woolly rhinoceros, the musk ox, the bison, the aurochs, and the reindeer became prevalent, and the temperate vegetation gave place to plants of a more arctic type. The glaciers spread southward to the maximum of the Fourth Glacial Age (about 50,000 years ago), and then receded again. In the earlier phase, the Third Interglacial period, a certain number of small family groups of men (Homo Neanderthalensis) and probably of sub-men (Eoanthropus) wandered over the land, leaving nothing but their flint implements to witness to their presence. They probably used a multitude and variety of wooden implements also; they had probably learnt much about the shapes of objects and the use of different shapes from wood, knowledge which they afterwards applied to stone; but none of this wooden material has survived; we can only speculate about its forms and uses. As the weather hardened to its maximum of severity, the Neanderthal men, already it would seem acquainted with the use of fire, began to seek shelter under rock ledges and in caves—and so leave remains behind them. Hitherto they had been accustomed to squat in the open about the fire, and near their water supply. But they were sufficiently intelligent to adapt themselves to the new and harder conditions. (As for the sub-men, they seem to have succumbed to the stresses of this Fourth Glacial Age altogether. At any rate, the rudest type of Palæolithic implements presently disappears.)
Not merely man was taking to the caves. This period also had a cave lion, a cave bear, and a cave hyæna. These creatures had to be driven out of the caves and kept out of the caves in which these early men wanted to squat and hide; and no doubt fire was an effective method of eviction and protection. Prob-