Key concepts in population change and growth

Population dynamics involve the study of how and why populations change over time. This includes understanding the rapid growth seen in many developing countries since the mid-20th century and the various metrics used to measure these changes.

Essential terms in population studies

• Population explosion - Refers to the dramatic increase in population numbers in developing regions after 1950, driven by high birth rates and declining death rates.
• Birth rate - The number of live births per 1,000 people in a population each year.
• Death rate - The number of deaths per 1,000 people in a population annually.
• Rate of natural change - Calculated as the difference between birth rate and death rate. A positive value indicates natural increase, while a negative value shows natural decrease.
• Rate of net migration - The difference between immigration (people moving into an area) and emigration (people leaving an area), affecting overall population size.
• Total fertility rate (TFR) - The average number of children a woman is expected to have during her lifetime.
• Infant mortality rate (IMR) - The number of deaths of children under one year of age per 1,000 live births in a year.
• Life expectancy at birth - The average number of years a newborn is expected to live based on current mortality trends.
• Depopulation - A reduction in the number of people within a population, often due to high death rates or emigration.

Factors influencing population size and change

Population size and growth rates are influenced by a combination of natural and human factors, which vary across regions and over time.

Reasons for differing rates of natural population change

• Healthcare access - Improvements in medical care reduce death rates, especially infant mortality, contributing to population growth.
• Education and gender equality - Higher education levels, particularly for women, often correlate with lower birth rates due to delayed marriage and career focus.
• Economic conditions - Poverty can lead to higher birth rates as families rely on children for labour or security, while economic development often reduces fertility rates.
• Cultural and religious beliefs - Some cultures or religions encourage larger families, maintaining high birth rates even as other factors change.
• Urbanisation - Urban living tends to lower birth rates due to higher living costs and smaller family norms compared to rural areas.
• Government policies - Policies can directly influence population growth through incentives or restrictions on family size.

Migration as a factor in population change

Migration impacts population size through the balance of people entering (immigration) and leaving (emigration) an area. Positive net migration increases population, while negative net migration contributes to depopulation.