THE EVOLUTION OF INTELLIGENCE 115 



greatly complicated by the difficulty of separating out those 

 factors which are indicative of sheer intellectual capacity and 

 those which have to do with the accidental advantages of cli- 

 matic or geographic habitat and the equally accidental develop- 

 ments of particular technical or social practices. It is easy to 

 assume that more elaborate forms of civilization necessarily 

 imply higher intellectual powers and this is perhaps not wholly 

 true. So far as we can judge by the evidence in historic times, 

 there is no reason whatever to suppose that the native intel- 

 lectual abilities of the average American citizen are in any 

 way superior to those of the Egyptians four thousand years 

 before Christ, or the Homeric Greeks, or to others of the 

 peoples of that general period in the Mediterranean basin, 

 records of whose civilization have come more or less com- 

 pletely to our knowledge. It would certainly be a bold protago- 

 nist who should assert that modern European civilization 

 has produced, in sheer intellectual power, men superior to 

 Democritus, or Plato, or Aristotle, or Alexander, or Julius 

 Caesar, to say nothing of great Orientals like Confucius. In 

 other words, since the period of historic records there is no 

 convincing evidence of marked development in human intelli- 

 gence, despite the enormous advances made in the parapher- 

 nalia of civilization; but, on the other hand, there is fairly 

 definite evidence that extant human races differ appreciably in 

 their native intelligence and those which are living most nearly 

 in the state of nature which we believe to have characterized 

 the early history of our own racial stock are, generally speak- 

 ing, marked by apparently lower general average intelligence 

 and by relatively fewer intellects of high grade. It seems 

 therefore a reasonable inference that the forefathers of our 

 own particular racial stock, could we but penetrate far enough 

 into past history, would be found, like the more primitive 

 races to-day, in possession of somewhat lower degrees of in- 

 tellectual capacity. How many thousands of years we might 



