74 THE RISE OF MAN. 



creation although it was slow enough if measured by the 

 rapid changes of the present time, and this is one main 

 reason why there are so few traces of man's activity in 

 the incipient stage of his manhood. All further steps of 

 anthropogenesis through the stone ages, the paleolithic, 

 the mesolithic, and the neolithic, can be traced at least in 

 large outlines, and in the bronze age the dawn of history 

 already begins to shed a clearer light upon the further ad- 

 vance of mankind toward civilization. 



In the neolithic period the pace of civilization enters 

 into a new period of unprecedented progress. Of the ab- 

 rupt changes at the beginning of this period Dr. Wood- 

 ruff says : 



"An apparently sudden appearance of neolithic cul- 

 ture also depends upon the fact that civilization increases 

 in a geometrical rate, because each new invention adds 

 something to all previous ones, or acts as a multiplier, 

 not a mere addition. Great inventions also are often a 

 mere assembling of many previous minor ones. The 

 steam engine for instance was built up of thousands of in- 

 ventions, dating back even to the discovery of metals, and 

 it is but one factor in all subsequent advance. It is also 

 a matter of comment that great revolutionizing inventions 

 are really very simple affairs. The advance in culture is 

 so tremendously rapid now, not because the multiplier is 

 any greater than with the mesolithic savage but because 

 the multiplicand is tremendous. It is quite likely that a 

 colony of modern farmers suddenly made ignorant of met- 

 als and transported to our iron fields, would take just as 

 long, if not longer, to discover metals on their farms than 

 did neolithic man, for they invent and discover just as 

 slowly as ever. Marsh's estimate of 12,000 years for a 

 savage to civilize himself must be entirely too short. It 

 must have taken 160,000 years for paleolithic inventions 

 to accumulate sufficiently to amount to a mesolithic stage, 



