| In 1971 there were about 3,700 million
people in the world. If the population were{{U}} (21) {{/U}}evenly over
the earth' s surface there would be about 50 people to the square mile; but
there are vast areas of desert and mountain and tropical forest{{U}} (22)
{{/U}}are uninhabited,{{U}} (23) {{/U}}at the other{{U}} (24)
{{/U}}, in the great cities millions may live within a few square
miles. {{U}} (25) {{/U}}of the world' s population is concentrated on only a small{{U}} (26) {{/U}}of the earth' s land surface, in the rich valleys and{{U}} (27) {{/U}}plains, because people up to the present time have{{U}} (28) {{/U}}to congregate in place where the climate and soil make it easy to grow food and obtain shelter. A{{U}} (29) {{/U}}world population and the discoveries of science{{U}} (30) {{/U}}this pattern of distribution in the future. As men slowly learn to master diseases, control floods, prevent famines, and stop wars, fewer people die every year; and in{{U}} (31) {{/U}}the population of the world is steadily{{U}} (32) {{/U}}. When numbers{{U}} (33) {{/U}}, the extra mouths must be fed. New lands must be brought{{U}} (34) {{/U}}cultivation, or land already{{U}} (35) {{/U}}, made to yield larger crops. In some areas the accessible land is largely so intensively cultivated{{U}} (36) {{/U}}it will be difficult to make it{{U}} (37) {{/U}}more food. in some areas the population is so dense that the land is divided into. units{{U}} (38) {{/U}}tiny to allow for much improvement in farming methods.{{U}} (39) {{/U}}a large part of this farming population drawn{{U}} (40) {{/U}}into industrial occupations, the land might be farmed much more productively by modern methods. |