The
vast population increase of the 21th
century have been accompanied by advances in agriculture. Domestic
animals supply about 8 million metric tons of wheat. Rather smaller
quantity of rice provides the main food of human population. Lesser
elements are an annual 82 million metric tons of sugar. About 6
million metric tons of fish are caught in the ocean month.
Population
tend to grow rapidly to the highest level at which the available
technology can provide sustenance, and then remain constant.
As technology becomes more sophisticated, population increase.
Thomas Malthus, the British economist and pioneer in the modern study
of population, failed to predict technological change and
consequently underestimated future growth in both populations and
their incomes.
Much
contemporary discussion of population is framed in terms of
demographic model in which deaths decline from a level
of about 30 per 1000each year to about 10 per 1000. After a longer or
a shorter lag the decline in deaths is followed by a decline births
from about 45 per 1000 or higher to about 20 per 1000 or lower. No
one knows whether the fall in the death rate directly causes
the fall in the birthrate that follows it. The time lag separating
the fall in births from the fall in deaths is of crucial
importance. With a delay of 45 years it can multiply fourfold.
With a delay of 75 years it can multiply ninefold. What is certain is
that if no fall in birthrate occurs, the death rate will have to rise
in those countries which are technologically backward. Only a
certain number of people will be able to support themselves within a
given territory through subsistence agriculture.
