New Book 4, Part 2 (School Mathematics Project Numbered Books) (Bk.4 Pt. 2) Book

"In traditional rural societies, awareness of the problems created by demographic growth was probably more immediate than it is in modern society. The inhabitants of a village, valley, or region experienced directly the negative effects of new settlement in an area already demographically saturated, and, while less efficient than those of the present day, regulating mechanisms could gradually bring about the necessary adjustments. The expansion and integration of markets and the development of trade have contributed to masking from individual perception the link between natural resources (land, for example) and consumer goods. Hong Kong can grow out of all measure, importing agricultural products from the United States or Argentina, without any awareness of the connection between the grain or beef consumed and the rural environment which produces them. This sort of detachment is a necessary consequence of economic development, but it should be pointed out that as a result the direct link between the protagonist of demographic choice (the individual) and the producer of the forces of constraint (the environment) has been broken. This link is slowly being reestablished as the minority of individuals, institutions, and governments that now recognize the global nature and interconnectedness of environmental phenomena increases.

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While modern society may be better equipped with regard to the regulation of mortality and fertility than societies of the past, the same cannot be said with regard to another mechanism of choice, namely migration. The peopling of the world has been accomplished by means of migration and settlement which has distributed population according to existing or potential resources. Emigration has also always been the principal route of escape from poverty and destitution. This 'freedom' of settlement, which in modern times has led to the Europeanization of temperate America and Australia, is today much impaired. In response to primarily political considerations, nations generally regard immigration as a marginal fact, acceptable only within a fairly rigid framework and in small numbers. Given the enormous national differences in wages and assets and the relative ease of mobility, perhaps it could not have been otherwise. Nonetheless, it is also the case that there exists no open and available territory to act as an outlet for demographic excess and to colonize with human population, plants, and animals. In addition, greater economic integration (for example, the increased value of international trade in relation to production) is accompanied by greater separation of peoples and ethnic groups; the creation of new national states, often bounded by unnatural borders, has led to the redistribution of ethnic groups, previously mixed, within well-defined political units; and a tendency toward segregation between groups is also frequent within national borders. So the effectiveness of an important tool of 'choice,' migration, has declined as compared to the past.

Our balance sheet, then, has both credit and debit entries, and it is not easy to calculate the bottom line, though the ability to control fertility, when it becomes universal, will constitute the decisive factor for controlling growth."