SOCIAL EVOLUTION 123 



tion is that it greatly helps the weaker in intellect to 

 rise. The man of poor mind can share the ideas and 

 discoveries of the genius. The race rises as a whole, 

 so that after the Ice Age we are not surprised to find 

 rapid progress. The stimulus to progress given by 

 social life would be checked, as long as the hard 

 conditions lasted, by the desperate struggle for food 

 and warmth. The new increase of intelligence helped, 

 because it created better weapons — the spear, bow 

 and arrow, hafted axe, etc. — but the severity of the 

 conditions would tend to distract and absorb energy. 

 When the last ice-sheet had melted, and Europe 

 recovered at least the degree of warmth it has to-day, 

 the new race, the men of the New Stone Age, spread 

 over it. In this the stimulus to progress was partly 

 checked. Tribes lost all communication with others, 

 and stagnated. Progress would be most in the south, 

 where groups were nearer each other. 



I am, of course, neglecting the greater part of the 

 human family in this sketch. No doubt it had been 

 distributed over the earth before the Ice Age, but it 

 was chiefi}^ the branch of the family which turned 

 towards Europe that experienced the full stimulation 

 of the Ice Age. During the greatest extension of the 

 ice-sheet this branch of the race would, to a large 

 extent, retreat south, across the land bridges to 

 North Africa and Asia minor. There would be a 

 relatively thick population from the Persian Gulf to 

 Algeria, and this would be thickest from the Persian 



