COLIN CLARK 
land was no longer available to provide subsistence in the 
manner hitherto customary, our ancestors had to turn, no 
doubt with great reluctance, to domesticating animals and to 
agriculture. 
Even after the establishment of agriculture, historical records 
show that periods of sustained population growth are rare, and 
stagnation or decline frequent. 
The real success story of population growth provoking 
economic improvement, the model for other countries to follow, 
is Japan. When the modernization of the country began, Japan 
was a poorer and more backward country than any Asian 
country is now. Population was growing at the rate of 1 per 
cent per annum, soon to rise to a rate of nearly 2 per cent. 
Unlike African and many Asian countries, which have con- 
siderable land to spare, Japan was already, in the nineteenth 
century, very densely populated. Nevertheless, from the 1880's 
onwards, the Japanese were able to increase the output from 
their own agriculture and fisheries, quite apart from any food 
they could import, at the rate of 3:5 per cent per annum, far 
ahead of the rate of population increase. This rate of improve- 
ment in agricultural production was continued up to the 
1920’s, by which time Japan had little need to worry, as she was 
earning enough from exports to import a considerable part of 
her food requirements, as Britain does. 
Let us not, however, talk as if we were trying to force the 
whole of mankind on to a cereal diet. Even if it is not physio- ° 
logically necessary, we enjoy a diet of meat and dairy products. 
How much land is required to produce them, if we do the job 
properly? 
Let us take as our standard the United States rate of consump- 
tion of meat, go kilograms per person per year, half of which is 
to be in the form of beef and mutton produced from grass, and 
half pig and poultry meat from cereals. To produce 1 kilogram 
of pigmeat (corresponding to 1-33 kilograms of live pig) 
requires, in the hands of good pig breeders, 5-3 kilograms of 
cereals. To produce 1 kilogram of poultry meat (1-5 kilograms 
of live bird) requires, in the best modern practice, 3°75 
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