Immigration and Emigration

There are two types of migration. Immigration and emigration. Immigrants (moving into the towns/countries) are the movements of individuals from other regions into the population. Emigration(leaving a place/country) is individual migrations out of the population. Both immigration and emigration affect the size of the desired country’s population. Immigration adds to the population and emigration cuts down a specific amount of people from the population.

Population size is also influenced by the fertility rate, infant mortality rate, and the age structure of the population.

• Total Fertility Rates (TFR): TFR is defined as the average number of children that would bear by a woman in her lifetime if the age-specific birth rates remain constant. The value of TFR varies from 1.9 in developed countries and 4.7 in developing countries.
• Infant Mortality Rate: It is an important parameter that affects the future growth of a population. It is the percentage of infants that died out of those born in a year.
• Replacement Level: This is an important concept in population dynamics and demography Two parents bearing two children will be replaced by their offspring.
• Age Structure: The age Structure of a population can be represented by age pyramids, based upon people belonging to different age classes like pre-reproductive(0-14 years), reproductive(15-44 years), and post-reproductive (45 years and above). We get three types of age pyramids:
  • Pyramid shaped: Here the very young population is more, making the broad base and old people less. A large number of individuals at a very young age will soon enter reproductive age, thus causing an increase in population. This type indicates a growing population. India, Bangladesh, Ethiopia, and Nigeria are examples of this type. 
  • Bell Shaped: It occurs in countries like France, the USA, and Canada, where birth rates have in the past one or two decades, declined to result in people of almost equal number in the age group 0-35 years. So in the next 10 years, the people entering the reproductive age group are not going to change much and such age pyramids indicate a stable population.
  • Urn Shaped: Here the number of individuals at a very young age is smaller than in the middle reproductive age class. In the next 10 years, the number of reproductive-age classes will thus become less than before resulting in a decline in population growth. Germany, Italy, Hungary, Sweden, and Japan are examples of this type.

Related Links

1. Characteristics of the Population
2. Population Composition
3. Population Growth and Process of Population Change in India

The major components of population growth include birth rate, death rate, and migration. The birth rate refers to the number of live births per thousand persons in a year and is one of the major components of population growth in India as birth rates have been always higher than death rates. Migration can be both internal as well as international, it doesn’t change the population but influences the distribution of population situated within the country an important role in changing composition as well as distribution of population.

The population is defined as a group of individuals or groups of the same species or society who live simultaneously in a particular dwelling or environment. Population growth was slow and stable till 1900, but exponential growth occurred after the 1930s following technological growth. In 1800, the earth was home to about 1 billion people. It took about 39 years of human history to reach 1 billion, 130 years to reach the second billion, 45 years to reach 4 billion, and the next doubling is likely within a span of a very few decades.