THE NUMBERS OF MEN 91 



This being so at least three possible alternative inferences 

 present themselves. The first of these is that the human popula- 

 tion of this globe more or less steadily grew for 500,000 years, 

 but at an extremely slow time rate as compared with the growth 

 performance of any but a very few populations now existing. 

 On this hypothesis it may be regarded as probable that growth 

 of world population was not entirely steady and continuous 

 along a smooth curve, logistic or other, but instead was irregular, 

 fluctuating up and down about the ever rising time-trend line. 



A second possible alternative is that for a long time — thou- 

 sands of years — prior to the seventeenth century the population 

 of the world stood stable at between roughly four and five 

 hundred million, or oscillated in waves of relatively small 

 amplitude about some such figure. On such a view this value 

 would represent a relatively stable upper asymptotic level 

 achieved in a cycle of population growth that was consummated 

 long before, and at a relatively early stage of man's evolution. 



Finally a third possible alternative is that during some period 

 or periods in this vast span of 500,000 odd years of man's life 

 on the earth the world f ovulation was much higher than 445 

 million, and subsequently lessened, for reasons wholly unknown, 

 to reach that final figure at the time when reasonably reliable 

 population history begins. 



Which of these three alternatives is true? No one can say 

 with any authority. But all the relevant evidence seems to 

 indicate that there were as many (or more) human beings living 

 on the face of the earth in 1630 as there ever had been at any 

 prior time since man set up in business for himself. Most par- 

 ticularly, to be counted against the third alternative is the fact 

 that until recent times man's culture was not of the sort to 

 make possible the existence of large populations on the earth. 

 As was pointed out in the preceding lecture hunting, pastoral, 

 and primitive agricultural cultures are not compatible with large 

 total populations, as we know them nowadays, because high 

 densities cannot be supported at these cultural levels or stages. 



Similarly the evidence seems definitely to be against the 

 second hypothesis. 



