Population growth

In biology or human geography, population growth is the increase in the number of individuals in a population. Many of the world's countries, including many in Sub-Saharan Africa, the Middle East, South Asia and South East Asia, have seen a sharp rise in population since the end of the Cold War. The fear is that high population numbers are putting further strain on natural resources, food supplies, fuel supplies, employment, housing, etc. in some of the less fortunate countries. For example, the population of Chad has ultimately grown from 6,279,921 in 1993 to 10,329,208 in 2009,[1] further straining its resources. Vietnam, Mexico, Nigeria, Egypt, Ethiopia, and the DRC are witnessing a similar growth in population.

Global human population growth amounts to around 83 million annually,[2] or 1.1% per year. The global population has grown from 1 billion in 1800 to 7.616 billion[3] in 2018. It is expected to keep growing, and estimates have put the total population at 8.6 billion by mid-2030, 9.8 billion by mid-2050 and 11.2 billion by 2100.[4] Many nations with rapid population growth have low standards of living, whereas many nations with low rates of population growth have high standards of living.[5]

Population[6]
Years passed Year Billion
1800 1
127 1927 2
33 1960 3
14 1974 4
13 1987 5
12 1999 6
12 2011 7
12 2023* 8
14 2037* 9
18 2055* 10
33 2088* 11
*World Population Prospects 2017
(United Nations Population Division)

History

Population began growing rapidly in the Western world early in the industrial revolution of the late 18th century. The reasons for the "Modern Rise of Population"[7] were particularly investigated by the British health scientist Thomas McKeown (1912-1988). In his publications, McKeown challenged four theories about the population growth:

  1. McKeown stated that the growth in Western population, particularly surging in the 19th century, was not so much caused by an increase in fertility, but largely by a decline of mortality particularly of childhood mortality followed by infant mortality,[8][9]
  2. The decline of mortality could largely be attributed to rising standards of living, whereby McKeown put most emphasis on improved nutritional status,
  3. His most controversial idea, at least his most disputed idea, was that he questioned the effectiveness of public health measures, including sanitary reforms, vaccination and quarantine,[10]
  4. The sometime fierce disputes that his publication provoked around the "McKeown thesis", have overshadowed his more important and largely unchallenged argument that curative medicine measures played little role in mortality decline, not only prior to the mid-20th century[8] but also until well into the 20th century.[11]

Although the McKeown thesis has been heavily disputed, recent studies have confirmed the value of his ideas.[12] His work is pivotal for present day thinking about population growth, birth control, public health and medical care. McKeown had a major influence on many population researchers, such as health economists and Nobel prize winners Robert W. Fogel (1993) and Angus Deaton (2015). The latter considered McKeown as "the founder of social medicine".[13]

Population growth rate

The "population growth rate" is the rate at which the number of individuals in a population increases in a given time period, expressed as a fraction of the initial population. Specifically, population growth rate refers to the change in population over a unit time period, often expressed as a percentage of the number of individuals in the population at the beginning of that period. This can be written as the formula, valid for a sufficiently small time interval:

A positive growth rate indicates that the population is increasing, while a negative growth rate indicates that the population is decreasing. A growth ratio of zero indicates that there were the same number of individuals at the beginning and end of the period—a growth rate may be zero even when there are significant changes in the birth rates, death rates, immigration rates, and age distribution between the two times.[14]

A related measure is the net reproduction rate. In the absence of migration, a net reproduction rate of more than 1 indicates that the population of females is increasing, while a net reproduction rate less than one (sub-replacement fertility) indicates that the population of females is decreasing.

Most populations do not grow exponentially, rather they follow a logistic model. Once the population has reached its carrying capacity, it will stabilize and the exponential curve will level off towards the carrying capacity, which is usually when a population has depleted most its natural resources.[15]

Logistic growth graph (population ecology)
The logistic growth of a population.

Logistic equation

The growth of a population can often be modelled by the logistic equation[16]

where

  • = the population after time t;
  • = time a population grows;
  • = the relative growth rate coefficient;
  • = the carrying capacity of the population; defined by ecologists as the maximum population size that a particular environment can sustain.[15]

As it is a separable differential equation, the population may be solved explicitly, producing a logistic function:

,

where and is the initial population at time 0.

Human population growth rate

Countriesbyfertilityrate
A world map showing global variations in fertility rate per woman according to the CIA World Factbook's 2016 data
World population (UN)
Estimates of population evolution in different continents between 1950 and 2050 according to the United Nations. The vertical axis is logarithmic and is in millions of people.
World population growth rate 1950–2050
World population growth rates between 1950–2050

In 2017, the estimated annual growth rate was 1.1%.[17] The CIA World Factbook gives the world annual birthrate, mortality rate, and growth rate as 1.86%, 0.78%, and 1.08% respectively.[18] The last 100 years have seen a massive fourfold increase in the population, due to medical advances, lower mortality rates, and an increase in agricultural productivity[19] made possible by the Green Revolution.

The annual increase in the number of living humans peaked at 88.0 million in 1989, then slowly declined to 73.9 million in 2003, after which it rose again to 75.2 million in 2006. In 2017, the human population increased by 83 million.[17] Generally, developed nations have seen a decline in their growth rates in recent decades, though annual growth rates remain above 2% in poverty-stricken countries of the Middle East and Sub-Saharan Africa, and also in South Asia, Southeast Asia, and Latin America.[20]

In some countries the population is declining, especially in Eastern Europe, mainly due to low fertility rates, high death rates and emigration. In Southern Africa, growth is slowing due to the high number of AIDS-related deaths. Some Western Europe countries might also experience population decline.[21] Japan's population began decreasing in 2005; it now has the highest standard of living in the world.[22]

The United Nations Population Division projects world population to reach 11.2 billion by the end of the 21st century, but Sanjeev Sanyal has argued that global fertility will fall below the replacement rate in the 2020s and that world population will peak below 9 billion by 2050, followed by a long decline.[23] A 2014 study in Science concludes that the global population will reach 11 billion by 2100, with a 70% chance of continued growth into the 22nd century.[24]

Growth by country

According to United Nations population statistics, the world population grew by 30%, or 1.6 billion humans, between 1990 and 2010.[25] In number of people the increase was highest in India (350 million) and China (196 million). Population growth was among highest in the United Arab Emirates (315%) and Qatar (271%).[25]

Growth rates of the world's most populous countries
Rank Country Population
2010
Population
1990
Growth (%)
1990–2010
  World 6,895,889,000 5,306,425,000 30.0%
1  China 1,341,335,000 1,145,195,000 17.1%
2  India 1,224,614,000 873,785,000 40.2%
3  United States 310,384,000 253,339,000 22.5%
4  Indonesia 239,871,000 184,346,000 30.1%
5  Brazil 194,946,000 149,650,000 30.3%
6  Pakistan 173,593,000 111,845,000 55.3%
7  Nigeria 158,423,000 97,552,000 62.4%
8  Bangladesh 148,692,000 105,256,000 41.3%
9  Russia 142,958,000 148,244,000 -3.6%
10  Japan 128,057,000 122,251,000 4.7%

Many of the world's countries, including many in Sub-Saharan Africa, the Middle East, South Asia and South East Asia, have seen a sharp rise in population since the end of the Cold War. The fear is that high population numbers are putting further strain on natural resources, food supplies, fuel supplies, employment, housing, etc. in some of the less fortunate countries. For example, the population of Chad has ultimately grown from 6,279,921 in 1993 to 10,329,208 in 2009,[1] further straining its resources. Vietnam, Mexico, Nigeria, Egypt, Ethiopia, and the DRC are witnessing a similar growth in population.

The following table gives some example countries:

Example nation 1967 population 1990 population 1994 population 2002 population 2008 population Life expectancy in years (2008) Total population growth from 1960s to 2007- 2011
Eritrea* N/A* N/A* 3,437,000[26] 4,298,269 5,673,520[27] 61[28][28] 2,236,520
Ethiopia* 23,457,000*[29] 50,974,000* [30] 54,939,000[26] 67,673,031(2003) 79,221,000[31] 55[28] 55,764,000
Sudan 14,355,000†[29] 25,204,000† [30] 27,361,000†[26] 38,114,160 (2003)† 42,272,000†[27] 50†[28] 27,917,000
Chad 3,410,000[29] 5,679,000[30] 6,183,000[26] 9,253,493(2003) 10,329,208 (2009)[1] 47[28] 6,919,205
Niger 3,546,000[29] 7,732,000[30] 8,846,000[26] 10,790,352 (2001) 15,306,252 (2009)[32] 44[28] 11,760,252
Nigeria 61,450,000[29] 88,500,000[30] 108,467,000[26] 129,934,911 158,259,000[27] 47[28] 96,809,000
Mali 4,745,000[29] 8,156,000[30] 10,462,000[26] 11,340,480 14,517,176(2010)[33] 50[28] 9,772,176
Mauritania 1,050,000[29] 2,025,000 [30] 2,211,000[26] 2,667,859 (2003) 3,291,000 (2009)[1] 54[28] 2,241,000
Senegal 3,607,000[29] 7,327,000[30] 8,102,000[26] 9,967,215 13,711,597 (2009)[34] 57[28] 10,104,597
Gambia 343,000[29] 861,000[30] 1,081,000[26] 1,367,124 (2000) 1,705,000[27] 55[28] 1,362,000
Algeria 11,833,126 (1966)[29] 25,012,000[30] 27,325,000 [26] 32,818,500 (2003) 34,895,000[31][35] 74[28] 23,061,874
The DRC/Zaire 16,353,000[29] 35,562,000[30] 42,552,000[26] 55,225,478 (2003) 70,916,439 [31][36] 54[28] 54,563,439
Egypt 30,083,419 (1966)[29] 53,153,000[30] 58,326,000[26] 70,712,345 (2003) 79,089,650 [31][37][37] 72[28] 49,006,231
Réunion (overseas region of France) 418,000[29] N/A[30] N/A[26] 720,934 (2003) 827,000 (2009) [27] N/A[28] 409,000
The Falkland Islands (British Overseas Territory) 2,500[29] N/A[30] N/A[26] 2,967 (2003) 3,140(2010)[38] N/A[28] 640
Chile 8,935,500[29] 13,173,000[30] 13,994,000[26] 15,116,435 17,224,200 (2011) 77[28] 8,288,700
Colombia 19,191,000[29] 32,987,000[30] 34,520,000[26] 41,088,227 45,925,397 (2010)[39] 73[28] 26,734,397
Brazil 85,655,000[29] 150,368,000[30] 153,725,000[26] 174,468,575 (2000) 190,732,694 (2010) [40] 72[28] 105,077,694
Mexico 45,671,000[29] 86,154,000[30] 93,008,000[26] 103,400,165 (2000) 112,322,757 (2010)[41] 76[28] 66,651,757
Fiji 476,727 (1966)[29] 765,000[30] 771,000[26] 844,330 (2001) 849,000[35] (2010) 70[28] 372,273
Nauru 6,050 (1966)[29] 10,000[30] N/A[26] 12,329 9,322 (2011)[42] N/A[28] 3,272
Jamaica 1,876,000[29] 2,420,000[30] 2,429,000[26] 2,695,867 (2003) 2,847,232[43](2010) 74[28] 971,232
Australia 11,540,764 (1964)[29] 17,086,000[30] 17,843,000[26] 19,546,792 (2003) 25,190,365[44] (2010) 82[28] 10,066,508
Albania 1,965,500 (1964)[29] 3,250,000[30] 3,414,000[26] 3,510,484 2,986,952 (July 2010 est.)[1][45] 78[28] 1,021,452
Poland 31,944,000[29] 38,180,000[30] 38,554,000[26] 38,626,349 (2001) 38,192,000 (2010)[46] 75[28] 6,248,000
Hungary 10,212,000[29] 10,553,000[30] 10,261,000[26] 10,106,017 9,979,000 (2010)[47] 73[28] -142,000
Bulgaria 8,226,564 (1965)[29] 8,980,000[30] 8,443,000[26] 7,707,495(2000) 7,351,234 (2011)[48] 73[28] -875,330
United Kingdom 55,068,000 (1966)[29] 57,411,000[30] 58,091,000[26] 58,789,194 62,008,048 (2010)[49] 79[28] 7,020,048
Ireland 2,884,002 (1966)[29] 3,503,000[30] 3,571,000[26] 3,840,838 (2000) 4,470,700[50] (2010) 78[28] 1,586,698
People's Republic of China 720,000,000[29] 1,139,060,000[30] 1,208,841,000[26] 1,286,975,468 (2004) 1,339,724,852 (2010)[51] 73[28] 619,724,852
Japan‡ 98,274,961 (1965)[29] 123,537,000[30] 124,961,000[26] 127,333,002 127,420,000 (2010)[52] 82[28] 28,123,865
Ryukyu Islands (Once occupied by the United States)‡ 934,176 (1965)[29] N/A N/A N/A N/A N/A N/A
India# 511,115,000[29] 843,931,000[30] 918,570,000[26] 1,028,610,328 (2001) 1,210,193,422 (2011)[53] 69[28] 699,078,422
Singapore 1,956,000 (1967)[29] 3,003,000 (1990) [30] 2,930,000 (1994)[26] 4,452,732 (2002) 5,076,700 (2010)[54] 82 (2008)[28] 3,120,700
Sikkim# 183,000 (1967)[29] N/A N/A N/A N/A N/A N/A
Monaco 24,000 (1967)[29] 29,000 (1990) [30] N/A (1994)[26] 31,842 (2000) 35,586[55] (2010) (2008)[28] 11,586
Greece 8,716,000 (1967)[29] 10,123,000 (1990) [30] 10,426,000 (1994)[26] 10,964,020 (2001)[56] 11,305,118 (2011)[57] N/A (2008)[28] 2,589,118
Faroe Islands (Danish dependency) 38,000 (1967)[29] N/A (1990) [30] N/A (1994)[26] 46,345 (2000) 48,917 (2010) [58] N/A (2008)[28] 18,917
Liechtenstein 20,000 (1967)[29] 29,000 (1990) [30] N/A (1994)[26] 33,307 (2000) 35,789 (2009)[59] (2008)[28] 15,789
South Korea 29,207,856 (1966)[29] 42,793,000 (1990) [30] 44,453,000 (1994)[26] 48,324,000 (2003) 48,875,000 (2010) [60] (2008)[28] 19,667,144
North Korea 12,700,000 (1967)[29] 21,773,000 (1990) [30] 23,483,000 (1994)[26] 22,224,195 (2002) 24,051,218 (2010)[61] (2008)[28] 11,351,218
Brunei 107,200 (1967)[29] 266,000 (1990) [30] 280,000 (1994)[26] 332,844 (2001) 401,890 (2011)[62] 76 (2008)[28] 306,609
Malaysia 10,671,000 (1967)[29] 17,861,000 (1990) [30] 19,489,000 (1994)[26] 21,793,293 (2002) 27,565,821 (2010)[63] (2008)[28] 16,894,821
Thailand 32,680,000 (1967)[29] 57,196,000 (1990) [30] 59,396,000 (1994)[26] 60,606,947 (2000)[64] 63,878,267 (2011)[65] (2008)[28] 31,198,267
Lebanon 2,520,000 (1967)[29] 2,701,000 (1990) [30] 2,915,000 (1994)[26] 3,727,703[66] (2003) 4,224,000[27] (2009) - (2008)[28]
Syria 5,600,000 (1967)[29] 12,116,000 (1990) [30] 13,844,000 (1994)[26] 17,585,540 (2003) 22,457,763 (2011)[67] -(2008)[28]
Bahrain 182,00 (1967)[29] 503,000 (1990) [30] 549,000 (1994)[26] 667,238 (2003) 1,234,596[68] (2010) 75 (2008)[28]
Sri Lanka 11,741,000 (1967)[29] 16,993,000 (1990) [30] 17,685,000 (1994)[26] 19,607,519 (2002) 20,238,000[35] (2009) - (2008)[28]
Switzerland 6,050,000 (1967)[29] 6.712,000 (1990) [30] 6,994,000 (1994)[26] 7,261,200 (2002) 7,866,500[69] (2010) - (2008)[28]
Luxembourg 335,000 (1967)[29] 381,000 (1990) [30] 401,000 (1994)[26] 439,539 (2001) 511,840 (2011)[70] - (2008)[28]
Romania 19,105,056 (1966)[29] 23,200,000 (1990)[30] 22,736,000 (1994)[26] 21,680,974 (2002) 21,466,174[71] (2011) - (2008)[28]
Niue (associated state of New Zealand) 1,900 (1966)[29] N/A (1990)[30] N/A (1994)[26] 2,134 (2002) 1,398 (2009)[72] N/A (2008)[28] -502
Tokelau (New Zealand territory) 5,194 (1966)[29] N/A (1990)[30] N/A (1994)[26] 1,445 (2001) 1,416 (2009) N/A (2008)[28] -3,778
Jamaica 1,876,000 (1967)[29] 2,420,000 (1990) [30] 2,429,000 (1994)[26] 2,695,867 (2003) 2,847,232[43] (2010) 74 (2008)[28] 971,232
Argentina 32,031,000 (1967)[29] 32,322,000 (1990)[30] 34,180,000 (1994)[26] 37,812,817 (2002) 40,091,359 (2010) 74 (2008)[28] 8,060,359
France 49,890,660 (1967)[29] 56,440,000 (1990)[30] 57,747,000 (1994)[26] 59,551,000 (2001) 63,136,180 (2011)[73] 81 (2008)[28]
Italy 52,334,000 (1967)[29] 57,662,000 (1990)[30] 57,193,000 (1994)[26] 56,995,744 (2002) 60,605,053[74] (2011) 80 (2008)[28]
Mauritius 774,000 (1967)[29] 1,075,000 (1990)[30] 1,104,000 (1994)[26] 1,179,137 (2000) 1,288,000 (2009)[35] 75 (2008)[28] 514,000
Guatemala 4,717,000 (1967)[29] 9,197,000 (1990)[30] 10,322,000 (1994)[26] 12,974,361 (2000) 13,276,517 (2009) 70 (2008)[28] 8,559,517
Cuba 8,033,000 (1967)[29] 10,609,000 (1990)[30] 10,960,000 (1994)[26] 11,177,743 (2002) 11,239,363 (2009)[75] 77 (2008)[28]
Barbados 246,000 (1967)[29] 255,000 (1990) [30] 261,000 (1994)[26] 250,012 (2001) 284,589 (2010)[1] 73 (2008)[28] 18,589
Samoa 131,377 (1967)[29] 164,000 (1990) [30] 164,000 (1994)[26] 178,173 (2003) 179,000 (2009)[27] N/A (2008)[28]
Sweden 7,765,981 (1967)[29] 8,559,000 (1990) [30] 8,794,000 (1994)[26] 8,920,705 (2002) 9,354,462 (2009) 81 (2008)[28]
Finland 4,664,000 (1967)[29] 4,986,000 (1990) [30] 5,095,000 (1994)[26] 5,175,783 (2002) 5,374,781 (2010) N/A (2008)[28]
Portugal 9,440,000 (1967)[29] 10,525,000 (1990)[30] 9,830,000 (1994)[26] 10,355,824 (2001) 10,647,763[76] (2011) N/A (2008)[28]
Austria 7,323,981 (1967)[29] 7,712,000 (1990) [30] 8,031,000 (1994)[26] 8,032,926 (2001) 8,404,252 (2011) N/A (2008)[28]
Libya 1,738,000 (1967)[29] 4,545,000 (1990)[30] 5,225,000(1994)[26] 5,499,074 (2002) 6,420,000 (2009)[27] 77 (2008)[28]
Peru 12,385,000 (1967)[29] 21,550,000 (1990)[30] 23,080,000(1994)[26] 27,949,639 (2002) 29,496,000 (2010) 70 (2008)[28]
Guinea Bissau 528,000 (1967)[29] 965,000 (1990) [30] 1,050,000 (1994)[26] 1,345,479 (2002) 1,647,000[27] (2009) 48 (2008)[28]
Angola 5,203,066 (1967)[29] 10,020,000 (1990)[30] 10,674,000 (1994)[26] 10,766,500 (2003) 18,498,000[35][77] (2009) 38 (2008)[28]
Equatorial Guinea 277,000 (1967)[29] 348,000 (1990)[30] 389,000 (1994)[26] 474,214 (2000) 676,000 (2009)[35] 61 (2008)[28]
Benin 2,505,000 (1967)[29] 4,736,000 (1990)[30] 5,246,000 (1994)[26] 8,500,500 (2002) 8,791,832 (2009) 59 (2008)[28]
Laos 2,770,000 (1967)[29] 4,139,000 (1990)[30] 4,742,000 (1994)[26] 5,635,967 (2002) 6,800,000[78] (2011) 56 (2008)[28]
Nepal 10,500,000 (1967)[29] 18,961,000 (1990)[30] 21,360,000 (1994)[26] 25,284,463 (2002) 29,331,000[35] (2009) - (2008)[28]
Iran 25,781,090 (1966)[29] 54,608,000 (1990)[30] 59,778,000 (1994)[26] 66,622,704 (2002) 75,330,000 (2010)[79] 71 (2008)[28]
Canada 20,014,880 (1966)[29] 26,603,000 (1990)[30] 29,248,000(1994)[26] 31,081,900 (2001) 32,623,490 (2011)[80] 81 (2008)[28]
United States 199,118,000 (1967)[29] 249,995,000 (1990)[30] 260,650,00(1994)[26] 281,421,906 (2000) 308,745,538 (2010)[81] 78 (2008)[28]
Uganda 7,931,000 (1967)[29] 18,795,000 (1990)[30] 20,621,000 (1994)[26] 24,227,297 (2002) 32,369,558 (2009) 52 (2008)[28]
Notes
* Eritrea left Ethiopia in 1991.
† Split into the nations of Sudan and South Sudan during 2011.
‡ Japan and the Ryukyu Islands merged in 1972.
# India and Sikkim merged in 1975.
Population growth 1990–2012 (%)[82]
Africa 73.3%
Middle East 68.2%
Asia (excl. China) 42.8%
China 19.0%
OECD Americas 27.9%
Non-OECD Americas 36.6%
OECD Europe 11.5%
OECD Asia Oceania 11.1%
Non-OECD Europe and Eurasia -0.8%
Overpopulation in Hồ Chí Minh City, Vietnam
Thousands of scooters make their way through the city of Hồ Chí Minh, Vietnam.

Growth by region

Population growth rates vary by world region, with the highest growth rates in Sub-Saharan Africa and the lowest in Europe. For example, from 1950 to 2010, Sub-Saharan Africa grew over three and a half times, from about 186 million to 856 million. On the other hand, Europe only increased by 35%, from 547 million in 1950 to 738 million in 2010. As a result of these varying population growths, Sub-Saharan Africa changed from 7.4% of world population in 1950 to 12.4% in 2010, while Europe declined from 22% to 11% in the same time period. [83]

Into the future

Population curve
Estimated size of human population from 10,000 BCE to 2000 CE.
Growthbydevelopedvslessdeveloped
The majority of world population growth today is occurring in less developed countries.

According to the UN's 2017 revision to its population projections, world population is projected to reach 11.2 billion by 2100 compared to 7.6 billion in 2017.[84][85] In 2011, Indian economist Sanjeev Sanyal disputed the UN's figures and argued that birth rates will fall below replacement rates in the 2020s. According to his projections, population growth will be only sustained till the 2040s by rising longevity, but will peak below 9 bn by 2050.[23] Conversely, a 2014 paper by demographers from several universities and the United Nations Population Division projected that the world's population would reach about 10.9 billion in 2100 and continue growing thereafter.[86] One of its authors, Adrian Raftery, a University of Washington professor of statistics and of sociology, says "The consensus over the past 20 years or so was that world population, which is currently around 7 billion, would go up to 9 billion and level off or probably decline. We found there’s a 70 percent probability the world population will not stabilize this century. Population, which had sort of fallen off the world’s agenda, remains a very important issue."[87]

See also

References

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  6. ^ United Nations - World Population Prospects 2017
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  11. ^ McKeown T, Record RG, Turner RD (1975). "An Interpretation of the Decline of Mortality in England and Wales during the Twentieth Century". Population Studies. 29 (3): 391–422. doi:10.1080/00324728.1975.10412707. JSTOR 2173935. PMID 11630508.CS1 maint: Multiple names: authors list (link)
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  13. ^ Deaton, Angus (2013). The Great Escape. Health, wealth, and the origins of inequality. Princeton and Oxford: Princeton University Press. pp. 91–93. ISBN 978 0 691 15354 4. McKeown's views, updated to modern circumstances, are still important today in debates between those who think that health is primarily determined by medical discoveries and medical treatment and those who look to the background social conditions of life.
  14. ^ Association of Public Health Epidemiologists in Ontario Archived 2008-05-22 at the Wayback Machine
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External links

2nd millennium

The second millennium was a period of time spanning the years AD 1001 to 2000 (11th to 20th centuries). It encompassed the High and Late Middle Ages of the Old World, followed by the Early Modern period, characterized by the Wars of Religion in Europe, the Age of Enlightenment, the Age of Discovery and the colonial period. Its final two centuries coincide with Modern history, characterized by industrialization, the rise of nation states, the rapid development of science, widespread education, and universal health care and vaccinations in the Western world. The 20th century saw increasing globalization, most notably the two World Wars and the subsequent formation of the United Nations. 20th-century technology includes powered flight, television and semiconductor technology, including integrated circuits. The term "Great Divergence" was coined to refer the unprecedented cultural and political ascent of the Western world in the second half of the millennium, emerging by the 18th century as the most powerful and wealthy world civilization, having eclipsed Qing China and the Islamic World.

World population grew without precedent over the millennium, from 310 million in AD 1000 to about 6,000 million in AD 2000.

Doubling time was at first seven centuries (reaching 600 million in 1700), and during the final three centuries population growth accelerated extremely, growth rate peaking at 1.8% p.a. in the second half of the 20th century. Unchecked globalization and population growth also caused considerable social and environmental consequences, giving rise to extreme poverty, climate change and biotic crisis.

Demographics of Africa

The population of Africa has grown rapidly over the past century and consequently shows a large youth bulge, further reinforced by a low life expectancy of below 50 years in some African countries.

Total population as of 2017 is estimated at more than 1.25 billion, with a growth rate of more than 2.5% p.a.

The most populous African country is Nigeria with 191 million inhabitants as of 2017 and a growth rate of 2.6% p.a.

Demographics of India

India is the second most populated country in the world with nearly a fifth of the world's population. According to the 2017 revision of the World Population Prospects, the population stood at 1,324,171,354.

During 1975–2010 the population doubled to 1.2 billion. The Indian population reached the billion mark in 1998. India is projected to be the world's most populous country by 2024, surpassing the population of China. It is expected to become the first political entity in history to be home to more than 1.5 billion people by 2030, and its population is set to reach 1.7 billion by 2050. Its population growth rate is 1.13%, ranking 112th in the world in 2017.India has more than 50% of its population below the age of 25 and more than 65% below the age of 35. It is expected that, in 2020, the average age of an Indian will be 29 years, compared to 37 for China and 48 for Japan; and, by 2030, India's dependency ratio should be just over 0.4.India has more than two thousand ethnic groups, and every major religion is represented, as are four major families of languages (Indo-European, Dravidian, Austroasiatic and Sino-Tibetan languages) as well as two language isolates (the Nihali language spoken in parts of Maharashtra and the Burushaski language spoken in parts of Jammu and Kashmir (Kashmir).

Further complexity is lent by the great variation that occurs across this population on social parameters such as income and education. Only the continent of Africa exceeds the linguistic, genetic and cultural diversity of the nation of India.The sex ratio is 944 females for 1000 males (2016) (940 per 1000 in 2011) This ratio has been showing an upwards trend for the last two decades after a continuous decline in the last century.

Human overpopulation

Human overpopulation (or population overshoot) occurs when the ecological footprint of a human population in a specific geographical location exceeds the carrying capacity of the place occupied by that group. Overpopulation can further be viewed, in a long term perspective, as existing if a population cannot be maintained given the rapid depletion of non-renewable resources or given the degradation of the capacity of the environment to give support to the population. Changes in lifestyle could reverse overpopulated status without a large population reduction.The term human overpopulation refers to the relationship between the entire human population and its environment: the Earth, or to smaller geographical areas such as countries. Overpopulation can result from an increase in births, a decline in mortality rates, an increase in immigration, or an unsustainable biome and depletion of resources. It is possible for very sparsely populated areas to be overpopulated if the area has a meagre or non-existent capability to sustain life (e.g. a desert). Advocates of population moderation cite issues like quality of life, carrying capacity, and risk of starvation as a basis to argue for population decline. Scientists suggest that the human impact on the environment as a result of overpopulation, profligate consumption and proliferation of technology has pushed the planet into a new geological epoch known as the Anthropocene.

Human population planning

Human population planning is the practice of intentionally controlling the rate of growth of a human population. Historically, human population planning has been implemented with the goal of increasing the rate of human population growth. However, in the period from the 1950s to the 1980s, concerns about global population growth and its effects on poverty, environmental degradation and political stability led to efforts to reduce human population growth rates. More recently, some countries, such as China, Iran, and Spain, have begun efforts to increase their birth rates once again.

While population planning can involve measures that improve people's lives by giving them greater control of their reproduction, a few programs, most notably the Chinese government's "one-child policy and two-child policy", have resorted to coercive measures.

List of countries by population growth rate

This article includes a table of countries and self-governing dependent territories by annual population growth rate.

List of states and territories of the United States by population

The states and territories included in the United States Census Bureau's statistics include the 50 states, the District of Columbia and five permanently inhabited unincorporated island territories, including Puerto Rico.As of April 1, 2010, the date of the 2010 United States Census, the 9 most populous U.S. states contain slightly more than half of the total population. The 25 least populous states contain less than one-sixth of the total population. California, the most populous state, contains more people than the 21 least populous states combined, and Wyoming, the least populous state, has a population less than that of the 31 most populous U.S. cities.

Logistic function

A logistic function or logistic curve is a common "S" shape (sigmoid curve), with equation:

where

For values of x in the domain of real numbers from −∞ to +∞, the S-curve shown on the right is obtained, with the graph of f approaching L as x approaches +∞ and approaching zero as x approaches −∞.

The logistic function finds applications in a range of fields, including artificial neural networks, biology (especially ecology), biomathematics, chemistry, demography, economics, geoscience, mathematical psychology, probability, sociology, political science, linguistics, and statistics.

Malthusian growth model

A Malthusian growth model, sometimes called a simple exponential growth model, is essentially exponential growth based on the idea of the function being proportional to the speed to which the function grows. The model is named after Thomas Robert Malthus, who wrote An Essay on the Principle of Population (1798), one of the earliest and most influential books on population.

Malthusian models have the following form:

where

The model can also been written in the form of a differential equation:

dP/dt = rP

with initial condition: P(0)= P0

This model is often referred to as the exponential law. It is widely regarded in the field of population ecology as the first principle of population dynamics, with Malthus as the founder. The exponential law is therefore also sometimes referred to as the Malthusian Law. By now, it is a widely accepted view to analogize Malthusian growth in Ecology to Newton's First Law of uniform motion in physics.

Malthus wrote that all life forms, including humans, have a propensity to exponential population growth when resources are abundant but that actual growth is limited by available resources:

A model of population growth bounded by resource limitations was developed by Pierre Francois Verhulst in 1838, after he had read Malthus' essay. Verhulst named the model a logistic function.

Malthusianism

Malthusianism is the idea that population growth is potentially exponential while the growth of the food supply is linear. It derives from the political and economic thought of the Reverend Thomas Robert Malthus, as laid out in his 1798 writings, An Essay on the Principle of Population. Malthus believed there were two types of "checks" that in all times and places kept population growth in line with the growth of the food supply: "preventive checks", such as moral restraints (abstinence, delayed marriage until finances become balanced), and restricting marriage against persons suffering poverty or perceived as defective, and "positive checks", which lead to premature death such as disease, starvation and war, resulting in what is called a Malthusian catastrophe. The catastrophe would return population to a lower, more "sustainable", level. Malthusianism has been linked to a variety of political and social movements, but almost always refers to advocates of population control.Neo-Malthusianism is the advocacy of population control programs to ensure resources for current and future populations. In Britain the term 'Malthusian' can also refer more specifically to arguments made in favour of preventive birth control, hence organizations such as the Malthusian League. Neo-Malthusians differ from Malthus's theories mainly in their enthusiasm for contraception. Malthus, a devout Christian, believed that "self-control" (abstinence) was preferable to artificial birth control. In some editions of his essay, Malthus did allow that abstinence was unlikely to be effective on a wide scale, thus advocating the use of artificial means of birth control as a solution to population "pressure". Modern "neo-Malthusians" are generally more concerned than Malthus with environmental degradation and catastrophic famine than with poverty.

Malthusianism has attracted criticism from a diverse range of differing schools of thought, including Marxists and socialists, libertarians and free market enthusiasts, social conservatives, feminists and human rights advocates, characterising it as excessively pessimistic, misanthropic or inhuman. Many critics believe Malthusianism has been discredited since the publication of Principle of Population, often citing advances in agricultural techniques and modern reductions in human fertility. Many modern proponents believe that the basic concept of population growth eventually outstripping resources is still fundamentally valid, and "positive checks" are still likely in humanity's future if there is no action to curb population growth.

Muslim population growth

Muslim population growth is the population growth of Muslims worldwide. In 2006, countries with a Muslim majority had an average population growth rate of 1.8% per year (when weighted by percentage Muslim and population size). This compares with a world population growth rate of 1.1% per year. As of 2011, it was predicted that the world's Muslim population will grow twice as fast as non-Muslims over the next 20 years. By 2030, Muslims will make up more than a quarter of the global population.Globally, Muslims have the highest fertility rate, an average of 2.9 children per woman—well above replacement level (2.1) and also a younger age profile (median age of 24) compared to other religious groups. Hindu fertility (2.4) is similar to the global average (2.5). Worldwide, Jewish fertility (2.3 children per woman) also is above replacement level. Most of the religious groups have fertility levels too low to sustain their populations and would require converts to grow or maintain their size: indigenous and tribal religions (1.8 children per woman), other religions (1.7), the unaffiliated (1.7) and Buddhists (1.6)."This significant projected growth is largely due to the young age and high fertility rate of Muslims". According to Pew Research, religious conversion has no net impact on the Muslim population as the number of people who convert to Islam is roughly similar to those who leave Islam.

A 2007 Center for Strategic and International Studies report argued that some Muslim population projections are overestimated, as they assume that all descendants of Muslims will become Muslims even in cases of mixed parenthood.

Negative Population Growth

Negative Population Growth is a membership organization in the United States, founded in 1972.

NPG works on overpopulation issues and advocates a gradual reduction in U.S. and world population. NPG believes the optimal population for the United States is 150 to 200 million and that the optimal world population is two to three billion. In order to accomplish their goal of a smaller U.S. population, the organization promotes policies which would reduce the fertility rate in the U.S. to 1.5 births per woman, and they advocate for reducing the level of immigration into the United States to 100,000 to 200,000 per year from the existing level of over 1.5 million per year.Membership stands at more than 25,000.

Population

In biology, a population is all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding. The area of a sexual population is the area where inter-breeding is potentially possible between any pair within the area, and where the probability of interbreeding is greater than the probability of cross-breeding with individuals from other areas.In sociology, population refers to a collection of humans. Demography is a social science which entails the statistical study of human populations.

Population in simpler terms is the number of people in a city or town, region, country or world; population is usually determined by a process called census (a process of collecting, analyzing, compiling and publishing data)

This article refers mainly to human population.

Population Connection

Population Connection (formerly Zero Population Growth or ZPG) is a non-profit organization in the United States that raises awareness of population challenges and advocates for improved global access to family planning and reproductive health care. The organization was founded in 1968 by Paul R. Ehrlich, Richard Bowers and Charles Remington in the wake of Ehrlich's best-selling book, The Population Bomb. The organization adopted its current name in 2002.

Population dynamics

Population dynamics is the branch of life sciences that studies the size and age composition of populations as dynamical systems, and the biological and environmental processes driving them (such as birth and death rates, and by immigration and emigration). Example scenarios are ageing populations, population growth, or population decline.

Projections of population growth

Projections of population growth established in 2017 predict that the human population is likely to keep growing until 2100, reaching an estimated 8.6 billion in 2030, 9.8 billion in 2050 and 11.2 billion by 2100, while the 7 billion milestone was reached in 2011. As the demographic transition follows its course worldwide, the population will age significantly, with most countries outside Africa trending towards a rectangular age pyramid.The world population is currently growing by approximately 83 million people each year. Growth rates are slowing to various extents within different populations with result of the overall population growth rate decreasing from 1.55% per year in 1995 to 1.25% in 2005, 1.18% in 2015 and 1.10% in 2017. The median estimate for future growth sees the world population reaching 8.6 billion in 2030, 9.8 billion in 2050 and 11.2 billion by 2100 assuming a continuing decrease in average fertility rate from 2.5 births per woman in 2010–2015 to 2.2 in 2045–2050 and to 2.0 in 2095–2100, according to the medium-variant projection. With longevity trending towards uniform and stable values worldwide, the main driver of future population growth is the evolution of the fertility rate.While most scenarios still predict continued growth into the 22nd century, there is a roughly 27% chance that the total population could stabilize or begin to fall before 2100. Longer-term speculative scenarios over the next two centuries can predict anything between runaway growth to radical decline (36.4 billion or 2.3 billion people in 2300), with the median projection showing a slight decrease followed by a stabilization around 9 billion people.By 2070, the bulk of the world's population growth is predicted to take place in Africa: of the additional 2.4 billion people projected between 2015 and 2050, 1.3 billion will be added in Africa, 0.9 billion in Asia and only 0.2 billion in the rest of the world. Africa's share of global population is projected to grow from 16% in 2015 to 25% in 2050 and 39% by 2100, while the share of Asia will fall from 60% in 2015 to 54% in 2050 and 44% in 2100. The strong growth of the African population will happen regardless of the rate of decrease of fertility, because of the exceptional proportion of young people already living today. For example, the UN projects that the population of Nigeria will surpass that of the United States by 2050. The population of the more developed regions is slated to remain mostly unchanged, at 1.2 billion, as international migrations from high-growth regions compensate the fertility deficit of richer countries.

Thomas Robert Malthus

Thomas Robert Malthus (; 13 February 1766 – 23 December 1834) was an English cleric and scholar, influential in the fields of political economy and demography. Malthus himself used only his middle name, Robert.In his 1798 book An Essay on the Principle of Population, Malthus observed that an increase in a nation's food production improved the well-being of the populace, but the improvement was temporary because it led to population growth, which in turn restored the original per capita production level. In other words, mankind had a propensity to utilize abundance for population growth rather than for maintaining a high standard of living, a view that has become known as the "Malthusian trap" or the "Malthusian spectre". Populations had a tendency to grow until the lower class suffered hardship, want and greater susceptibility to famine and disease, a view that is sometimes referred to as a Malthusian catastrophe. Malthus wrote in opposition to the popular view in 18th-century Europe that saw society as improving and in principle as perfectible. He saw population growth as being inevitable whenever conditions improved, thereby precluding real progress towards a utopian society: "The power of population is indefinitely greater than the power in the earth to produce subsistence for man". As an Anglican cleric, Malthus saw this situation as divinely imposed to teach virtuous behaviour. Malthus wrote:

That the increase of population is necessarily limited by the means of subsistence,That population does invariably increase when the means of subsistence increase, and,That the superior power of population is repressed by moral restraint, vice and misery.

Malthus criticized the Poor Laws for leading to inflation rather than improving the well-being of the poor. He supported taxes on grain imports (the Corn Laws), because food security was more important than maximizing wealth. His views became influential, and controversial, across economic, political, social and scientific thought. Pioneers of evolutionary biology read him, notably Charles Darwin and Alfred Russel Wallace. He remains a much-debated writer.

World population

In demographics, the world population is the total number of humans currently living, and was estimated to have reached 7.6 billion people as of May 2018. It took over 200,000 years of human history for the world's population to reach 1 billion; and only 200 years more to reach 7 billion.World population has experienced continuous growth since the end of the Great Famine of 1315–1317 and the Black Death in 1350, when it was near 370 million.

The highest population growth rates – global population increases above 1.8% per year – occurred between 1955 and 1975, peaking to 2.06% between 1965 and 1970. The growth rate has declined to 1.18% between 2010 and 2015 and is projected to decline further in the course of the 21st century. However, the global population is still growing and is projected to reach about 10 billion in 2050 and more than 11 billion in 2100.

Total annual births were highest in the late 1980s at about 139 million, and as of 2011 were expected to remain essentially constant at a level of 135 million, while deaths numbered 56 million per year and were expected to increase to 80 million per year by 2040.

The median age of the world's population was estimated to be 30.4 years in 2018.

Zero population growth

Zero population growth, sometimes abbreviated ZPG (also called the replacement level of fertility), is a condition of demographic balance where the number of people in a specified population neither grows nor declines, considered as a social aim by some.

According to some, zero population growth, perhaps after stabilizing at some optimum population, is the ideal towards which countries and the whole world should aspire in the interests of accomplishing long-term environmental sustainability. What it means by ‘the number of people neither grows nor declines’ is that births plus in-migrants equal deaths plus out-migrants.

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