12 THE SHADOW OF THE WORLD’S FUTURE 
100,000 persons became only 100,002 after the lapse 
of a year. 
[t is when we realise how extraordinarily slow Man’s 
average rate of numerical increase has been in the 
past, that we grasp the true significance of his rate 
of increase during last century and during the century 
on which we have entered. For the latter rate would 
have given the world its existing population in about 
2000 years. With such a fact in view, and remembering 
that we start now with, say, 1950 millions, we cannot 
escape seeing that the world’s future is ominous. Thus 
suppose that the rate of increase was, as mentioned, 
about 0-864 per cent. it would double its population 
every 80-54 years, and thus we should have, were such 
increase possible, the following astonishing figures for 
the earth’s population, at the date-years indicated, 
viz. '— 
Date-years 1928 2008 2089 2169 2250 2330 
Millions - 1950 3900 7800 15,600% 31.200% 62,400% 
It will be shown later that the figures marked with 
asterisks are not possible populations for this earth; 
and thus we are driven to ask, * What then will bring 
about the limitation of human reproduction?” 
The existing situation may be stated in another way. 
The human race has reached a rate of increase which 
is not only enormously great as compared with its 
average rate in the past ; it is also one which cannot 
possibly extend far into the future, indeed it cannot 
continue for two centuries! 
The traces which still remain of past civilisations 
suggest that circumstances formerly existed which pro- 
foundly reacted upon the rate of human increase. Of 
these, however, we have no reliable record. Either life 
on earth has been subject to great vicissitudes, of which 
historically we know practically nothing—possibly some 
geological evidences remain-—or else Man’s powers of