We explain what populations are, how they are classified and their growth. Also, what are its characteristics and examples.
What is the population?
By the term, it usually refers to the group of individuals (generally human, but not exclusively) that make up a community or that inhabit a certain geographic area or space. It is often used in disciplines such as demography , ecology , and statistics.
The study of populations dates back to ancient times , when the considered father of demography, the Arab Ibn Aljún ( Abenjaldún in Spanish), composed his works in which he studied the formation of the Arab peoples, using statistical data for the first time in history .
The word “population” comes from the Latin populatio , “crowd” , and this from populus , which meant “people” or “citizenship”. Currently, populations are the subject of various studies and different analytical perspectives, which try to find the trends of formation, development and growth of the communities of our species.
The concept of population varies according to the specific discipline . For example, for demography, a population is a stable and constituted group of individuals, linked to each other by dynamics of reproduction and by a territorial, cultural, religious, political, ethnic and/or legal sense of identity.
On the other hand, for biology , ecology or sociology , a population is nothing more than a set of individuals that share a specific geography , thus being able to speak of human populations, populations of red foxes or microorganisms .
In the case of statistics , the concept becomes even more abstract : a population will be a determined set of elements, a portion of which will be subjected to scrutiny or study.
In principle, one can distinguish between human populations and animal populations or plant populations , depending on the nature of the individuals to be studied. In that sense, there would be as many types of populations as there are categories of them.
On the other hand, populations can be classified as follows, based on their biological considerations:
- family populations. Those in which individuals are united by a bond of consanguinity or kinship.
- gregarious populations. Those formed by groups of individuals not necessarily related, but who share some type of group movement, whether for migratory, defensive or predatory purposes: prides of lions , schools of fish , packs of dogs , etc.
- State populations. Those characterized by the hierarchy, specialization and distribution of tasks among their individuals, which makes isolated life possible.
- colonial populations. Those that form physically united individuals or that share very small spaces, in which they proliferate and from which they generally do not move, such as corals.
growth and decline
Populations, whatever their type, tend to grow (increase in the total number of individuals) or decrease (decrease in the total number of individuals), according to conditions that can be studied. They are between them:
- Availability of resources. Populations settled in a place where resources are more available (food, space, etc.) will have an important element in their favor to grow, while those that lack it will grow more slowly or, if the resources have suddenly disappeared, will start to decrease.
- Survival. If the conditions of a population allow a long life expectancy for its individuals, it is much more likely that they will reproduce more than once and lead their own lives to a happy end, while in much more ferocious conditions (wars, famines, etc.) .) populations tend to decrease, since their new individuals do not have time to reproduce.
- Mobility. Populations are not necessarily closed entities, and it is possible for individuals to change their population one or several times in their lives , causing one to grow and the other to decrease: a migrant decreases the starting population, but increases the destination population.
Natality and mortality
Two rates or central tendencies that constitute the growth and decrease of populations are the birth of new individuals and their death. These are processes that occur in all populations, as one generation replaces the other, but not in the exact same proportion.
To understand this process is on the one hand the concept of birth rate: the number of individuals born in a given period. On the other hand, the mortality rate: the number of individuals who die in a given period.
Both figures are compared, and thus we can know what fate awaits the population, for example:
- If the birth rate is much higher than the death rate, the population will grow rapidly.
- If the birth rate is just above the death rate, the population will grow slowly.
- If the birth rate is equal to the death rate, the population will neither increase nor decrease.
- If the death rate is much higher than the birth rate, the population will decrease vertiginously.
- If the death rate is slightly higher than the birth rate, the population will decrease slowly.
Population density (or relative population) is a calculation that averages the number of people and the space available for them to live. To do this, the total number of inhabitants is divided by the surface area of the territory (inhab/km 2 ), which yields a figure that will indicate how densely populated a location is.
If the density is high, the inhabitants have little space for themselves , since they are too many for the populated space; if on the contrary it is low, they will have a lot of space for themselves, since they are few for the populated space.
For example, the city of Buenos Aires has a population density of 14,458.8 inhabitants/km 2 , while the Canadian capital, Ottawa, has a density of 278.6 inhabitants/km 2 .
The number of individuals of each sex and age group in a population is commonly represented in a population pyramid, that is, a graph that places the sex groups and number of individuals on an X axis, and age on a Y axis.
Thus, a joint visualization of the population distribution is obtained based on their sex (men on the right and women on the left) and age, and depending on the longevity of the population, we can have these types of pyramid:
- expanding pyramid. Wide base and narrow top, indicate a predominance of the young population, decreasing in number as it ages. It is typical of populations with high birth and death rates.
- stationary pyramid. With a smaller base and less difference from the top, it indicates a predominant adult population, but with good survival, typical of mature populations with a higher quality of life.
- regressive pyramid. With a narrow base and more extensive peaks, indicative of a majority old population, the result of low mortality and birth rates, as in populations with reduced growth.
The analysis of the populations from an economic point of view shows two types of inhabitants:
- Economically active population. Those inhabitants who are inserted in the productive dynamics, that is, who are in physical and mental conditions to work , even if they are vacant at the moment. Also called Working Age Population.
- Economically inactive population. Those inhabitants unable to work for various physical or mental reasons. They are also known as dependent population, since it must be maintained by the active population.
Censuses are the instrument par excellence to register and learn about a population , especially human populations . It is done through the enumeration of the inhabitants and the detail of their characteristics, from a social, economic, family perspective, etc.
All this data is then processed and fed into the elaboration of statistics , which allows drivers and analysts of society to better understand its population trends.
The world population
The human population as a whole is, according to the 2009 census, about 7 billion inhabitants distributed throughout the earth’s surface, in the 194 recognized countries of the planet.
If one considers that in 1804 we were approximately a billion, and that in 1974 we already reached 4 billion, it will be seen that we are a growing total population, but at a slower and slower rate . It is estimated that we will reach a population balance around the year 2093, when we reach 11,500 million inhabitants.
Examples of population in its various meanings can be the population of common cockroaches that exists in the kilometers of pipes in your city, or the total inhabitants of the neighborhood where you live .
One can also speak of population to refer to the individuals in the electoral register or voter registration , or to those who voted according to one or another political tendency (numerically, since in a democracy the vote must be secret).
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