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From Wikipedia, the free encyclopedia

Distribution of world population in 1994.
Time taken for each billion people to be added to the world's population (including future estimates). See also alt. chart .

In biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings. Statistical study of human populations occurs within the discipline of demography. This article refers mainly to human population.

Contents

World human population

As of 18 March 2010, the world population is estimated by the United States Census Bureau to be 6.809 billion.[1]

According to papers published by the United States Census Bureau, the world population hit 6.5 billion (6,500,000,000) on 24 February 2006. The United Nations Population Fund designated 12 October 1999 as the approximate day on which world population reached 6 billion. This was about 12 years after world population reached 5 billion in 1987, and 6 years after world population reached 5.5 billion in 1993. However, the population of some countries, such as Nigeria and China is not even known to the nearest million[2], so there is a considerable margin of error in such estimates.[3]

Population growth increased significantly as the Industrial Revolution gathered pace from 1700 onwards[4]. The last 50 years have seen a yet more rapid increase in the rate of population growth[4] due to medical advances and substantial increases in agricultural productivity, particularly beginning in the 1960s,[5] made by the Green Revolution.[6] In 2007 the United Nations Population Division projected that the world's population will likely surpass 10 billion in 2055.[7] In the future, world population has been expected to reach a peak of growth, from there it will decline due to economic reasons, health concerns, land exhaustion and environmental hazards. There is around an 85% chance that the world's population will stop growing before the end of the century. There is a 60% probability that the world's population will not exceed 10 billion people before 2100, and around a 15% probability that the world's population at the end of the century will be lower than it is today. For different regions, the date and size of the peak population will vary considerably.[8]

Population control

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In humans

Map of countries and territories by fertility rate.

Human population control is the practice of curtailing population increase, usually by reducing the birth rate. Surviving records from Ancient Greece document the first known examples of population control. These include the colonization movement, which saw Greek outposts being built across the Mediterranean and Black Sea basins to accommodate the excess population of individual states. Infanticide and abortion were encouraged in some Greek city states in order to keep population down.[9]

An important example of mandated population control is People's Republic of China's one-child policy, in which having more than one child is made extremely unattractive. This has led to allegations that practices like forced abortions, forced sterilization, and infanticide are used as a result of the policy. The country's sex ratio at birth of 114 boys to 100 girls may be evidence that the latter is often sex-selective.

It is helpful to distinguish between fertility control as individual decision-making and population control as a governmental or state-level policy of regulating population growth. Fertility control may occur when individuals or couples or families take steps to decrease or to regulate the timing of their own child-bearing. In Ansley Coale's oft-cited formulation, three preconditions for a sustained decline in fertility are: (1) acceptance of calculated choice (as opposed to fate or chance or divine will) as a valid element in fertility, (2) perceived advantages from reduced fertility, and (3) knowledge and mastery of effective techniques of control.[10]

In contrast to a society with natural fertility, a society that desires to limit fertility and has the means to do so may use those means to delay childbearing, space childbearing, or stop childbearing. Delaying sexual intercourse (or marriage), or the adoption of natural or artificial means of contraception are most often an individual or family decision, not a matter of a state policy or societal-wide sanctions. On the other hand, individuals who assume some sense of control over their own fertility can also accelerate the frequency or success of child-bearing through planning.

At the societal level, declining fertility is almost an inevitable result of growing secular education of women. However, the exercise of moderate to high levels of fertility control does not necessarily imply low fertility rates. Even among societies that exercise substantial fertility control, societies with an equal ability to exercise fertility control (to determine how many children to have and when to bear them) may display widely different levels of fertility (numbers of children borne) associated with individual and cultural preferences for the number of children or size of families.[11]

In contrast to fertility control, which is mainly an individual-level decision, governments may attempt to exercise population control by increasing access to means of contraception or by other population policies and programs.[12] The idea of "population control" as a governmental or societal-level regulation of population growth does not require "fertility control" in the sense that it has been defined above, since a state can affect the growth of a society's population even if that society practices little fertility control. It's also important to embrace policies favoring population increase as an aspect of population control, and not to assume that states want to control population only by limiting its growth.

To stimulate population growth, governments may support not only immigration but also pronatalist policies such as tax benefits, financial awards, paid work leaves, and childcare to encourage the bearing of additional children.[13] Such policies have been pursued in recent years in France and Sweden, for example. With the same goal of increasing population growth, on occasion governments have sought to limit the use of abortion or modern means of birth control. An example was Romania under Nicolae Ceauşescu in 1966 banning access to contraception and abortion on demand.

In ecology, population control is on occasions considered to be done solely by predators, diseases, parasites, and environmental factors. In a constant environment, population control is regulated by the availability of food, water, and safety. The maximum number of a species or individuals that can be supported in a certain area is called the carrying capacity. At many times human effects on animal and plant populations are also considered.[14] Migrations of animals may be seen as a natural way of population control, for the food on land is more abundant on some seasons. The area of the migrations' start is left to reproduce the food supply for large mass of animals next time around. See also immigration.

India is an interesting example of changes in government measures to control the country’s population. The Indian government, concerned that the rapidly growing population would adversely affect economic growth and living standards implemented an official family planning program in the late 1950s and early 1960s; it was the first country in the world to do so. Later extreme policies backfired with writers such as Salman Rushdie's Midnight Children lambasting forced sterilisation of petty convicts and incentivised sterilisation during the Indian Emergency (1975-1977). Later, policitians and press reports named Sanjay Gandhi as the policy's governmental head.[15]

In animals

Animal population control is the practice of intentionally altering the size of any animal population besides humans. It may involve culling, translocation, or manipulation of the animal's reproduction.

See also

Notes

  1. ^ U.S. Census Bureau - World POPClock Projection
  2. ^ "Cities in Nigeria: 2005 Population Estimates — MongaBay.com". http://www.mongabay.com/igapo/2005_world_city_populations/Nigeria.html. Retrieved 1 July 2008. 
  3. ^ "Country Profile: Nigeria". BBC News. 24 December 2009. http://news.bbc.co.uk/2/hi/africa/country_profiles/1064557.stm. Retrieved 1 July 2008. 
  4. ^ a b As graphically illustrated by population since 10,000BC and population since 1000AD
  5. ^ BBC News "The end of India's green revolution?". 29 May 2006. http://news.bbc.co.uk/1/hi/world/south_asia/4994590.stm BBC News. Retrieved 29 November 2009. 
  6. ^ Food First/Institute for Food and Development Policy
  7. ^ United Nations Population Division (13 March 2007). "World population will increase by 2.5 billion by 2050; people over 60 to increase by more than 1 billion". Press release. http://www.un.org/News/Press/docs/2007/pop952.doc.htm. Retrieved 14 March 2007. "The world population continues its path towards population ageing and is on track to surpass 9 billion persons by 2050." 
  8. ^ "The End of World Population Growth". http://www.nature.com/nature/journal/v412/n6846/full/412543a0.html. Retrieved 4 November 2008. 
  9. ^  "Theories of Population". Catholic Encyclopedia. New York: Robert Appleton Company. 1913. http://en.wikisource.org/wiki/Catholic_Encyclopedia_(1913)/Theories_of_Population. 
  10. ^ Ansley J. Coale, "The Demographic Transition," Proceedings of the International Population Conference, Liège, 1973, Volume 1, pp. 53-72.
  11. ^ For illustrations of the distinction between fertility control and fertility levels, see Barbara A. Anderson and Brian D. Silver, "A Simple Measure of Fertility Control," Demography 29, No. 3 (1992): 343-356, and B. A. Anderson and B. D. Silver, "Ethnic Differences in Fertility and Sex Ratios at Birth: Evidence from Xinjiang," Population Studies 49 (1995): 211-226. The fundamental work on models of fertility control was that by Coale and his colleagues. See, e.g., Ansley J. Coale and James T. Trussell, “Model Fertility Schedules: Variations in the Age Structure of Childbearing in Human Populations.” Population Index 40 (1974): 185 – 258.
  12. ^ For a discussion of the range of "population policy" options available to governments, see Paul Demeny, "Population Policy: A Concise Summary," Population Council, Policy Research Division, Working Paper No. 173 (2003)[1].
  13. ^ Charlotte Höhn, "Population policies in advanced societies: Pronatalist and migration strategies," European Journal of Population/Revue européenne de Démographie 3, Nos. 3-4 (July, 1988): 459-481.
  14. ^ See http://en.wikipedia.org/wiki/Hunting#Wildlife_management.
  15. ^ Gwatkin, Davidson R. 'Political Will and Family Planning: The Implications of India’s Emergency Experience', in: Population and Development Review, 5/1, 29-59.

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