The inhabitants of a region or country who together comprise its native and immigrant people. While it is often used to define the boundary of the citizenry of a sovereign state, it is also used more specifically to refer to a group or category of people sharing specific characteristics, eg the working class population, the coloured population, and so on.
In biology, plant and animal populations are studied, in particular, in a branch of ecology known as population biology, and in population genetics. In population dynamics, size, age and sex structure, mortality, reproductive behaviour, and growth of a population are studied.
Population pyramid
The age and gender distribution of a population within a given nation or region is commonly represented by means of a population pyramid.
This type of chart displays the development of a population over a period of time.
Population growth
Population growth is change in population over time. The term population growth can technically refer to any species, but almost always refers to humans, and it is often used informally for the more specific demographic term population growth rate (see below), and is often used to refer specifically to the growth of the population of the world. It is most often applied to population growth although it can be used for any increasing quantity, such as price inflation or the volume of malignant tumours. For example, given Canada's net population growth of 0.9% in the year 2006, dividing 70 by .9 gives an approximate doubling time of 77.7 years. Thus if the growth rate remains constant, Canada's population will double from its current 33 million to 66 million by 2083.
Population decline
Population decline is a decrease in a region's population. The Black Death in Europe and the arrival of Old World diseases to the Americas all caused massive population declines.
In biology, population decline of a species is usually described as a result of gradually worsening environmental factors, such as prolonged drought or loss of inhabitable areas for the studied species. These, or other factors, may lead to a small population, in which case genetic factors may become dominant in the survival, or extinction of a population.
Population decline is recognized when there are more resources in an area (for example, food, energy and minerals) than can be used by the people living there. It is probable that standards of living would rise through increased production and exploitation of resources if population were to increase.
However, when making comparisons on a global scale, there does not seem to be any direct correlation between population density and over- or under-population. The Netherlands and Germany, for example, both have a high GDP per capita and a high population density whereas Canada and Australia have a high GDP per capita and a low population density, while Bangladesh has low GDP per capita and a high population density, etc.
The balance of population and resources within a country may be uneven. For example, a country may have a population, which is too great for one resource such as energy, yet too small to use fully a second such as food supply. The relationship between population and resources are highly complex and the terms "over-population" and "under-population" must therefore be used with extreme care.
Various attempts to address population decline have been made:
Improving communication networks and transport facilities makes remote places more accessible.Carrying capacity and population ceiling
Carrying capacity is the largest number of people that can be adequately supported by a given area of land.
Population control
Population control is the practice of curtailing population increase, usually by reducing the birth rate.
In ecology, population control is on occasions considered to be done solely by predators, diseases, parasites, and environmental factors.
Population transfer
biological aspects, see introduced species
Population transfer is a policy by which a state forces the movement of a large group of people from one region to another, often on the basis of their ethnicity or religion. In modern times, the region of Tibet has undergone heavy population transfer from the coastal regions of China, displacing the native Tibetans with ethnic Han Chinese.
World population
According to estimates published by the United States Census Bureau, the world population hit 6.5 billion (6,500,000,000) on February 25, 2006, at 7:16 p.m. Eastern Standard Time. The United Nations Population Fund designated October 12, 1999 as the approximate day on which world population reached six billion.
Countries by population
About 4 billion of the world's 6.5 billion people live in Asia. Seven of the world's ten largest countries by population are in Asia (although Russia is also located in Europe).
| Rank | Country | Population |
Density (people/ km²) |
|---|---|---|---|
| — | World | 6,661,208,350 | 43 |
| 1 | China | 1,315,844,000 | 136 |
| 2 | India | 1,110,000,000 | 328 |
| 3 | United States | 301,574,000 | 30 |
| 4 | Indonesia | 222,781,000 | 126 |
| 5 | Brazil | 186,405,000 | 21 |
| 6 | Pakistan | 164,000,000 | 202 |
| 7 | Bangladesh | 145,000,000 | 1,002 |
| 8 | Russia | 142,800,000 | 8 |
| 9 | Nigeria | 131,530,000 | 139 |
| 10 | Japan | 127,000,000 | 337 |
| 11 | Mexico | 107,000,000 | 54 |
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