Population Growth
Components of Population Change
There are three components of population change – births, deaths, and migration. The crude birth rate (CBR) is expressed as the number of live births in a year per thousand population.
Here, CBR = Crude Birth Rate; Bi = live births during the year; P=Mid-year population of the area.
The death rate plays an active role in population change. Population growth occurs not only by increasing the births rate but also due to decreasing the death rate. Crude Death Rate (CDR) is a simple method of measuring mortality in any area. CDR is expressed in terms of the number of deaths in a particular year per thousand of the population in a particular region.
CDR is calculated as:
Migration
Apart from birth and death, there is another way by which the population size changes. When people move from one place to another, the place they move from is called the Place of Origin, and the place they move to is called the Place of Destination. The place of origin shows a decrease in population while the population increases in the place of destination. Migration may be interpreted as a spontaneous effort to achieve a better balance between population and resources.
Migration may be permanent, temporary, or seasonal. It may take place from rural-to-rural areas, rural to urban areas, urban to urban areas, and urban to rural areas. Do you realize that the same person is both an immigrant and an emigrant?
Immigration: Migrants who move into a new place are called Immigrants.
Emigration: Migrants who move out of a place are called Emigrants.
TRENDS IN POPULATION GROWTH
The population on the earth is more than seven billion. It has grown to this size over the centuries. In the early period’s population of the world grew very slowly. It is only during the last few hundred years that the population has increased at an alarming rate. Fig. 2.2 tells the story of population growth. After the evolution and introduction of agriculture about 12,000 to 8,000 years ago, the size of the population was small – roughly 8 million. In the first century A.D., it was below 300 million. The expanding world trade during the sixteenth and seventeenth-century set the stage for rapid population growth. Around 1750, at the dawn of the Industrial Revolution, the world population was 550 million. The world population exploded in the eighteenth century after the Industrial Revolution. Technological advancement achieved so far helped in the reduction of the death rate and provided a stage for accelerated population growth.
SPATIAL PATTERN OF POPULATION CHANGE
Population growth in different parts of the world can be compared. The growth of population is low in developed countries as compared to developing countries. There is a negative correlation between economic development and population growth. Although the annual rate of population change (1.4 percent) seems to be low (Table 2.3), it is actually not so. This is because:
• When a small annual rate is applied to a very large population, it will lead to a large population change.
• Even if the growth rate continues to decline, the total population grows each year. The infant mortality rate may have increased as has the death rate during childbirth.
IMPACT OF POPULATION CHANGE
A small increase in population is desirable in a growing economy. However, population growth beyond a certain level leads to problems. Of these, the depletion of resources is the most serious. Population decline is also a matter of concern. It indicates that resources that had supported a population earlier are now insufficient to maintain the population.
The deadly HIV/AIDS epidemics in Africa and some parts of the Commonwealth of Independent States (CIS) and Asia have pushed up death rates and reduced average life expectancy. This has slowed down population growth.
Demographic Transition Theory
The demographic transition should not be regarded as a ‘law of population growth, but as a generalized description of the evolutionary process. In simple terms, it is a theory that attempts to specify general laws by which human populations change in size and structure during industrialization. It is frequently accepted as a useful tool in describing the demographic history of a country.
The theory postulates a particular pattern of demographic change from high fertility and high mortality to low fertility and low mortality when society progresses from a largely rural agrarian and illiterate society to a dominant urban, industrial, literate and modern society.
It is typically viewed as a three-stage process:
The demographic transition theory is characterized by conspicuous transition stages.
The transition from high birth and death rates to low rates can be divided into three stages (some scholars like Haggett, 1975 have divided them into four or five stages):
- Pre-transition stage – High and fluctuating birth and death rates with little population growth.
- Stage I: High birth rates and declining death rates with rapid population growth.
- Stage II: Low birth and death rates with slow population growth.
- Stage III: Birth and death rates both decline appreciably leading to zero population growth. The theory holds that pre-industrial societies were characterized by stable populations that had both a high death rate and birth rate. It postulates a little and slows population growth. The theory states that the high mortality rates characteristic of undeveloped areas will decline before fertility rates which are also high.
In the first stage, the country is at a low level of economic development. Agriculture is the main occupation of the people. The standard of living of the people is low. The death rate is high because of a lack of medical facilities, epidemics, famines, and illiteracy. The birth rate is high because of social and economic reasons. The key notable features of this stage are as follows:
- Population Pyramid in the first stage is Expanding at the bottom
- Stable population
- High birth rate, High infant mortality, and High death rate = low life expectancy
- Many young people, very few older people
- High fertility rate (8+)
- A society dominated by religious belief
- The stagnant economy, No surplus subsistence type of living
- Ex – Sierra Leone, Somalia
The first stage has high fertility and high mortality because people reproduce more to compensate for the deaths due to epidemics and variable food supply. The population growth is slow and most of the people are engaged in agriculture where large families are an asset. Life expectancy is low, people are mostly illiterate and have low levels of technology. Two hundred years ago all the countries of the world were at this stage.
Second Stage or Stage of High Birth Rate and Low Death Rate or Stage of Population Explosion
In this stage, the birth-rate is high but the death rate is low. It results in a high growth rate of the population. In this stage, income begins to rise and economic activities expand. On account of better health facilities and a nourishing diet, the death rate falls rapidly. The birth rate remains high due to social backwardness and limited access to contraceptives. The key notable features of this stage are as follows:
- Population Pyramid in this stage is Rapidly Expanding
- Very rapid increase in population (population explosion)
- Rapid decline in death rate but death rate remains below the birth rate
- Fertility rate remains high
- High birth rate
- High rate of natural increase
- Decline in infant mortality
- Many young people
Fertility remains high at the beginning of the second stage but it declines with time. This is accompanied by a reduced mortality rate. Improvements in sanitation and health conditions lead to a decline in mortality. Because of this gap, the net addition to the population is high.
Third Stage or Stage of Declining Birth Rate and Low Death Rate
In the third stage, a declining birth rate and low death rate lead to low population growth. Along with the economic development of the country, structural changes in the economy begin to take place. A large population begins to reside in urban areas. People start considering large families as a liability. Consequently, the birth rate begins to fall. The death rate continues to be low. The growth rate of the population declines. India is passing through this stage of demographic transition. The key notable features of this stage are as follows:
- The Population Pyramid in the third stage is Stationary
- Population growth slows down
- Birth rate declining rapidly
- The decline in fertility rate
- Death rate declining slowly
- Birth rate approaching death rate
- High life expectancy
- An increasing number of older people
Fourth Stage or Stage of Low Birth Rate and Low Death Rate
In the fourth stage, a low birth rate and a low death rate lead to Population stabilization. In this stage, because of rapid economic development, the standard of living of the people becomes very high. Quality of life is given a priority to the size of the family. The key notable features of this stage are as follows:
- Population Pyramid is Contracting
- Stable or slow population increase
- Low birth rate
- Low death rate
- High life expectancy
- Birth rate is approximately the same as the death rate
- The fertility rate is close to or below 2.1
- Many older people
In the last stage, both fertility and mortality decline considerably. The population is either stable or grows slowly. The population becomes urbanized, literate, and has the high technical know-how, and deliberately controls the family size. This shows that human beings are extremely flexible and are able to adjust their fertility. In the present day, different countries are at different stages of demographic transition.
Image Courtesy: NCERT Books
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