A population is all the organisms that both belong to the same species In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as based on similarity of DNA or and live in the same geographical area. The area that is used to define the population is such that inter-breeding In biology and specifically genetics, hybrid has several meanings, all referring to the offspring of sexual reproduction is possible between any pair within the area and more probable than cross-breeding with individuals from other areas. Normally breeding is substantially more common within the area than across the border.[1]

In sociology Sociology is the study of society. It is a social science—a term with which it is sometimes synonymous—that uses various methods of empirical investigation and critical analysis to develop and refine a body of knowledge about human social activity, often with the goal of applying such knowledge to the pursuit of social welfare. Subject matter, a collection of human Humans are a species of animal known taxonomically as Homo sapiens , and are the only extant member of the Homo genus of bipedal primates in Hominidae, the great ape family. However, in some cases "human" is used to refer to any member of the genus Homo beings. Statistical study of human populations occurs within the discipline of demography Demography is the statistical study of human populations. It can be a very general science that can be applied to any kind of dynamic human population, that is, one that changes over time or space . It encompasses the study of the size, structure and distribution of these populations, and spatial and/or temporal changes in them in response to. This article refers mainly to human population.

Contents

World human population

Main article: World population The world population is the population of humans on the planet Earth. In 2009, the United Nations estimated the population to reach 7,000,000,000 in 2011; current estimates by the United States Census Bureau put the population at 6,858,200,000

As of 27 July 2010, the world population is estimated Estimation is the calculated approximation of a result which is usable even if input data may be incomplete or uncertain by the United States Census Bureau The United States Census Bureau is the government agency that is responsible for the United States Census. It also gathers other national demographic and economic data. As part of the United States Department of Commerce, the Census Bureau serves as a leading source of data about America's people and economy to be 6.858 billion.[2]

According to papers published by the United States Census Bureau The United States Census Bureau is the government agency that is responsible for the United States Census. It also gathers other national demographic and economic data. As part of the United States Department of Commerce, the Census Bureau serves as a leading source of data about America's people and economy, the world population hit 6.5 billion (6,500,000,000) on 24 February 2006. The United Nations Population Fund The United Nations Population Fund began operations in 1969 as the United Nations Fund for Population Activities (the name was changed in 1987) under the administration of the United Nations Development Fund. In 1971 it was placed under the authority of the United Nations General Assembly 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 Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising thirty-six states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in the north. Its coast in the south lies on and China is not even known to the nearest million[3], so there is a considerable margin of error in such estimates.[4]

Population growth Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement. In biology, the term population growth is likely to refer to any known organism, but this article deals mostly with the application of the term increased significantly as the Industrial Revolution The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, and transport had a profound effect on the socioeconomic and cultural conditions starting in the United Kingdom, then subsequently spreading throughout Europe, North America, and eventually the world. The onset of the gathered pace from 1700 onwards[5]. The last 50 years have seen a yet more rapid increase in the rate Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement. In biology, the term population growth is likely to refer to any known organism, but this article deals mostly with the application of the term of population growth[5] due to medical advances All human societies have medical beliefs that provide explanations for birth, death, and disease. Throughout history, illness has been attributed to witchcraft, demons, adverse astral influence, or the will of the gods. These ideas still retain some power, with faith healing and shrines still used in some places, although the rise of scientific and substantial increases in agricultural productivity, particularly beginning in the 1960s,[6] made by the Green Revolution Green Revolution refers to a series of research, development, and technology transfer initiatives, occurring between 1943 and the late 1970s, that increased industrialized agriculture production in many developing nations.[7] In 2007 the United Nations Population Division projected that the world's population will likely surpass 10 billion in 2055.[8] 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.[9]

Population control

In humans

Main article: Human population control Map of countries and territories by fertility rate The total fertility rate (TFR, sometimes also called the fertility rate, period total fertility rate or total period fertility rate (TPFR)) of a population is the average number of children that would be born to a woman over her lifetime if (1) she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime, and (.

Human population control is the practice of curtailing population increase, usually by reducing the birth rate According to the United Nations' World Population Prospects: The 2008 Revision Population Database, crude birth rate is the number of births over a given period divided by the person-years lived by the population over that period. It is expressed as number of births per 1,000 population. CBR =. Surviving records from Ancient Greece Ancient Greece is the civilization belonging to the period of Greek history lasting from the Archaic period of the 8th to 6th centuries BC to 146 BC and the Roman conquest of Greece after the Battle of Corinth. At the center of this time period is Classical Greece, which flourished during the 5th to 4th centuries BC, at first under Athenian document the first known examples of population control. These include the colonization movement, which saw Greek Ancient Greece is the civilization belonging to the period of Greek history lasting from the Archaic period of the 8th to 6th centuries BC to 146 BC and the Roman conquest of Greece after the Battle of Corinth. At the center of this time period is Classical Greece, which flourished during the 5th to 4th centuries BC, at first under Athenian outposts being built across the Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant. The sea is technically a part of the Atlantic Ocean, although it is usually identified as a completely and Black Sea The Black Sea is an inland sea bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and Aegean Seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects it to the Aegean Sea region of the Mediterranean. These waters basins to accommodate the excess population of individual states. Infanticide Infanticide is the practice of intentionally killing an infant. Often it is the mother who commits the act, but criminology recognizes various forms of non-maternal child murder. In many past societies, certain forms of infanticide were considered permissible. Female infanticide is more common than the killing of male offspring due to sex- and abortion were encouraged in some Greek Ancient Greece is the civilization belonging to the period of Greek history lasting from the Archaic period of the 8th to 6th centuries BC to 146 BC and the Roman conquest of Greece after the Battle of Corinth. At the center of this time period is Classical Greece, which flourished during the 5th to 4th centuries BC, at first under Athenian city states in order to keep population down.[10]

An important example of mandated population control is People's Republic of China's one-child policy The one-child policy is the population control policy of the People's Republic of China (PRC). The Chinese government refers to it under the official translation of family planning policy. It officially restricts the number of children married urban couples can have to one, although it allows exemptions for several cases, including rural couples,, 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 Natural fertility is a concept developed by French demographer Louis Henry to refer to the level of fertility that would prevail in a population that makes no conscious effort to limit, regulate, or control fertility, so that fertility depends only on physiological factors affecting fecundity. In contrast, populations that practice fertility 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 Ansley Johnson Coale , was one of America's foremost demographers. A native of Baltimore, Maryland, he earned his B.A. in 1939, his M.A. in 1941, and (after a period of service in the Navy) his Ph.D. in 1947, all at Princeton University. A long-term director of the Office of Population Research at Princeton, Coale was especially influential for'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.[11]

In contrast to a society with natural fertility Natural fertility is a concept developed by French demographer Louis Henry to refer to the level of fertility that would prevail in a population that makes no conscious effort to limit, regulate, or control fertility, so that fertility depends only on physiological factors affecting fecundity. In contrast, populations that practice 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.[12]

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.[13] 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 Immigration is the introduction of new people into a habitat or population. It is a biological concept and is important in population ecology, differentiated from emigration and migration but also pronatalist policies such as tax benefits, financial awards, paid work leaves, and childcare to encourage the bearing of additional children.[14] 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 Romania (pronounced /roʊˈmeɪniə/ roe-MAY-nee-ə; dated: Rumania, Roumania; Romanian: România [romɨˈni.a] ( listen)) is a country located at the crossroads of Central and Southeastern Europe, north of the Balkan Peninsula, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea. Almost all of the Danube Delta under Nicolae Ceauşescu Nicolae Andruţă Ceauşescu ( 26 January 1918 – 25 December 1989) was the Secretary General of the Romanian Workers' Party, later the Romanian Communist Party from 1965 until 1989, President of the Council of State from 1967 and President of Romania from 1974 until 1989. His rule was marked in the first decade by an open policy towards Western in 1966 banning access to contraception and abortion on demand.

In ecology, population control is on occasions considered to be done solely by predators In ecology, predation describes a biological interaction where a predator feeds on its prey (the organism that is attacked). Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption. The other main, diseases A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal disfunctions, such as autoimmune diseases, parasites Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the host, 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 The carrying capacity of a biological species in an environment is the population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment. For the human population, more complex variables such as sanitation and medical care are sometimes considered as part. At many times human effects on animal and plant populations are also considered.[15] Migrations of animals may be seen as a natural way of population control, for the food on land is more abundant on some seasons A season is a division of the year, marked by changes in weather, ecology, and hours of daylight. The area of the migrations' start is left to reproduce the food supply for large mass of animals next time around. See also immigration Immigration is the introduction of new people into a habitat or population. It is a biological concept and is important in population ecology, differentiated from emigration and migration.

India India, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with 1.18 billion people, and the most populous democracy in the world. Mainland India is bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal on the 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 Sir Ahmed Salman Rushdie is a British-Indian novelist and essayist. He achieved notability with his second novel, Midnight's Children (1981), which won the Booker Prize in 1981. Much of his fiction is set on the Indian subcontinent. His style is often classified as magical realism mixed with historical fiction, and a dominant theme of his work is's Midnight Children lambasting forced sterilisation of petty convicts and incentivised sterilisation during the Indian Emergency (1975-1977) The Indian Emergency of 25 June 1975 – 21 March 1977 was a 21-month period, when President Fakhruddin Ali Ahmed, upon advice by Prime Minister Indira Gandhi, declared a state of emergency under Article 352 of the Constitution of India, effectively bestowing on her the power to rule by decree, suspending elections and civil liberties. It is one. Later, policitians and press reports named Sanjay Gandhi Sanjay Gandhi was an Indian politician, the younger son of former Prime Minister of India Indira Gandhi and politician Feroze Gandhi as the policy's governmental head.[16]

In animals

Main article: Animal population control
This section requires expansion.

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. The growth of animal population may be limited by environmental factors such as food supply or predation. The main Biotic Factors that effect population growth include:

Food- both the quantity and the quality of food are important. Snails, for example, cannot reproduce successfully in an environment low in calcium, no matter how much food there is, because they need this mineral for shell growth.

Predators- as a prey population becomes larger, it becomes easier for predators to find prey. If the number of predators suddenly falls, the prey species might increase in number extremely quickly.

Competitors- other organisms may require the same resources from the environment, and so reduce growth of a population.For example all plants compete for light. Competition for territory and for mates can drastically reduce the growth of individual organisms.

Parasites- These may cause disease, and slow down the growth and reproductive rate of organisms within a population.

Important Abiotic factors affecting population growth include:

Temperature- Higher temperatures speed up enzyme-catalyzed reactions and increase growth.

Oxygen availability- affects the rate of energy production by respiration.

Light availability- for photosynthesis. light may also control breeding cycles in animals and plants.

Toxins and pollutants- tissue growth can be reduced by the presence of, for example, sulphur dioxide, and reproductive success may be affected by pollutants such as estrogen like substances.

See also

Notes

  1. ^ Hartl, Daniel (2007). Principles of Population Genetics. Sinauer Associates. p. 45. ISBN 978-0-87893-308-2.
  2. ^ U.S. Census Bureau - World POPClock Projection
  3. ^ "Cities in Nigeria: 2005 Population Estimates — MongaBay.com". http://www.mongabay.com/igapo/2005_world_city_populations/Nigeria.html. Retrieved 1 July 2008.
  4. ^ "Country Profile: Nigeria". BBC News. 24 December 2009. http://news.bbc.co.uk/2/hi/africa/country_profiles/1064557.stm. Retrieved 1 July 2008.
  5. ^ a b As graphically illustrated by population since 10,000BC and population since 1000AD
  6. ^ 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.
  7. ^ Food First/Institute for Food and Development Policy
  8. ^ 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."
  9. ^ "The End of World Population Growth". http://www.nature.com/nature/journal/v412/n6846/full/412543a0.html. Retrieved 4 November 2008.
  10. ^ "Theories of Population". Catholic Encyclopedia. New York: Robert Appleton Company. 1913. http://en.wikisource.org/wiki/Catholic_Encyclopedia_(1913)/Theories_of_Population.
  11. ^ Ansley J. Coale, "The Demographic Transition," Proceedings of the International Population Conference, Liège, 1973, Volume 1, pp. 53-72.
  12. ^ 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.
  13. ^ 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].
  14. ^ 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.
  15. ^ See http://en.wikipedia.org/wiki/Hunting#Wildlife_management.
  16. ^ Gwatkin, Davidson R. 'Political Will and Family Planning: The Implications of India’s Emergency Experience', in: Population and Development Review, 5/1, 29-59.

External links

Hierarchy of life
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Sun, 25 Jul 2010 13:02:10 GM

This is because the more we reproduce, the greater the . population. of children. Canada had a rate 10.28 birth (per 1000 . population. ) with 16.1% of its . population. in the ages of 0-14, and Brazil had a birth rate of 18.43 with 26.7% of its ...

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