live longer. People in Europe and North America live, on the average,
twice as long as they did a hundred years ago. In other countries, too,
people generally live much longer than they once did. Babies,
especially, have a far better chance of growing up because of increased
protection against infant disease. 47. However, all countries do not
benefit to the same degree from this program in medicine and hygiene.
In prehistoric time, people from Africa and Asia migrated to other
continents. Europe was occupied by people from the East, America by
groups from Asia. During the nineteenth and twentieth centuries,
migrations have taken place within certain countries: the cities with
their industries have attracted people away from the country. 48. The
possibility of earning a fixed salary in a factory or office was more
attractive than the possibility of staying on the farm and having one’
s work destroyed by frost, storms, or droughts. Furthermore, the
development of agricultural machinery made it possible for fewer people
to do the same amount of work.
Thus, at the same time that the industrial revolution made it possible
to produce goods more cheaply and more quickly in factories, and
agricultural revolution also took place. Instead of leaving fields
empty every third year, farmers began to plant clover or some other
crop that would enrich the soil. Instead of using only animal
fertilizer, farmers began to use chemical fertilizers to keep the soil
rich. 49. These methods have enabled French farmers, for example, to
give five times as much wheat as was obtained from the same land two
centuries ago.
In many countries farmers find it more profitable to raise only one
crop or one kind of animal. They choose the kind that gives the best
results. Then they sell all that they produce, instead of trying to
grow a little of everything and consume what they grow. 50. This is a
more feasible type of operation because modern methods and machinery
are adapted to specific animals and specific crops. Therefore, it would
be too expensive to do all the work by hand, or to buy the equipment
needed for several different kinds of farming.
