BIOLOGY IN ITS WIDER ASPECTS 127 1 



agriculture may be discovered, but there is no immediate prospect 

 of an enormous improvement. No doubt, again, people can live 

 comfortably now where they did not think they could live comfort- 

 ably before, in places like Alaska, for instance; but all that has been 

 allowed for. 



Some optimists are always saying that some great biochemical 

 discovery will change the whole problem of human nutrition, but 

 this is only an off-chance ! As far as we know, there is strong proba- 

 bility that we must look out for the earth's saturation point being 

 reached at about 5,200,000,000 individuals, and at the present rate 

 this figure will be reached in a little over a century. That is a tact 

 that gives one pause. 



But will the population ever reach the limit ? There is some reason 

 to answer in the negative, for in individual countries the limit has 

 seldom been reached. This is due to a law, to speak metaphorically, 

 or to facts that are formulated in a law, that as the density of a 

 population increases there comes an automatic check on further 

 increase. The population curve worked out by Raymond Pearl is 

 something like a letter S made of copper wire, straightened out 

 at the two ends, a curve with an upper bend to the right and a 

 lower bend to the left. In individual countries, as the limit of 

 population has from time to time been approximated to, a decline 

 has set in or a crisis has occurred which has greatly reduced the 

 numbers. 



But what we have to look forward to is reducing the population 

 before the saturation point has been reached. That is the crux; to 

 bring about a reduction so that the stationary population will be a 

 population in relative comfort like that of France — happy on tfie 

 whole — and not in a position like that of China of to-day — over- 

 worked on the whole. And it is for science so to direct things that 

 the reduction of population comes about before the debacle of the 

 5,200,000,000 crowd. 



Is the falling birth rate general in any country ? Tlie answer, unfor- 

 tunately, is No! The decline of the birth rate is differential; it is 

 unequal in different sections of the community. In aU countries 

 farmers have more children than philosophers, and miners have 

 more children than millionaires. In some cases there is least decline 

 where it is most wanted; the wrong kind of people have too many 

 children, and the right kind of people have too few — that is the 

 lamentable fact. In England and Wales out of a hundred couples of, 

 say, teachers, what is the average number of children? Only 95! 

 — which is lamentable. A hundred couples of clergy leave progeny 

 from 96 to loi — 96 if they go to chapel, loi if they go to church. 

 That is to say, if you seek through 100 couples among the clergy, 

 the residue of offspring is between 96 and loi, about one for each 

 pair. On the other hand, when you come to miners, who are a 



