Overpopulation, the situation of having large numbers of people with too few resources and too little space, is closely associated with poverty. It can result from high population density (the ratio of people to land area, usually expressed as numbers of persons per square kilometer or square mile) or from low amounts of resources, or from both. Excessively high population densities put stress on available resources. Only a certain number of people can be supported on a given area of land, and that number depends on how much food and other resources the land can provide. In countries where people live primarily by means of simple farming, gardening, herding, hunting, and gathering, even large areas of land can support only small numbers of people because these labor-intensive subsistence activities produce only small amounts of food.In developed countries such as the United States, Japan, and the countries of western Europe, overpopulation generally is not considered a major cause of poverty. These countries produce large quantities of food through mechanized farming, which depends on commercial fertilizers, large-scale irrigation, andagricultural machinery. This form of production provides enough food to support the high densities of people in metropolitan areas.A country’s level of poverty can depend greatly on its mix of population density and agricultural productivity. Bangladesh, for example, has one of the world’s highest population densities, with 1,078 persons per sq km (2,791 persons per sq mi). A large majority of the people of Bangladesh engage in low-productivity manual farming, which contributes to the country’s extremely high level of poverty. Some of the smaller countries in western Europe, such as The Netherlands and Belgium, have high population densities as well. These countries practice mechanized farming and are involved in high-tech industries, however, and therefore have high standards of living.At the other end of the spectrum, many countries in sub-Saharan Africa have population densities of less than 30 persons per sq km (80 persons per sq mi). Many people in these countries practice manual subsistence farming; these countries also have infertile land and lack the economic resources and technology to boost productivity. As a consequence, these nations are very poor. The United States has both relatively low population density and high agricultural productivity; it is one of the world’s wealthiest nations.High birth rates contribute to overpopulation in many developing countries.Children are assets to many poor families because they provide labor, usually for farming. Cultural norms in traditionally rural societies commonly sanction the value of large families. Also, the governments of developing countries often provide little or no support, financial or political, for family planning; even people who wish to keep their families small have difficulty doing so. For all these reasons, developing countries tend to have high rates of population growth.Most developed countries provide considerable political and financial support for family planning. People tend to limit the number of children they have because of the availability of this support. Cultural norms in these countries also tend to affirm the ideal of small family size. Recently, however, some developed countries with declining population levels have begun experimenting with incentives to increase the birth rate.
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