terrible glacial periods which upon four different occasions
threatened to kill every human being on the face of the earth.

In the first place it was necessary that man clothe himself
lest he freeze to death. He learned how to dig holes and cover
them with branches and leaves and in these traps he caught
bears and hyenas, which he then killed with heavy stones and
whose skins he used as coats for himself and his family.

Next came the housing problem. This was simple. Many
animals were in the habit of sleeping in dark caves. Man now
followed their example, drove the animals out of their warm
homes and claimed them for his own.

Even so, the climate was too severe for most people and
the old and the young died at a terrible rate. Then a genius
bethought himself of the use of fire. Once, while out hunting,
he had been caught in a forest-fire. He remembered that he
had been almost roasted to death by the flames. Thus far fire
had been an enemy. Now it became a friend. A dead tree
was dragged into the cave and lighted by means of smouldering
branches from a burning wood. This turned the cave into
a cozy little room.

And then one evening a dead chicken fell into the fire. It
was not rescued until it had been well roasted. Man discovered
that meat tasted better when cooked and he then and there
discarded one of the old habits which he had shared with the
other animals and began to prepare his food.