How and why do populations change naturally?

1. How and why do populations change naturally?

2. Following a study of changes in birth and death rates in several developed countries in north America and Western Europe, researchers developed a model which suggests that all countries pass through similar population cycles, or demographic stages. The model suggests that changes in birth and death rates are linked to the development process.

4. Data to plot on graph

5. What are the reasons for the variations? • Many factors contribute to variations in both birth and death rates. • All countries have differing demographic transitions, depending on the social and economic circumstances which influences their birth and death rates.

6. Factors affecting fertility • In general, high fertility rates are associated with developing countries and low with developed countries. However, the generalisation does not always hold true due to a variety of local factors that affect birth rates….

7. Education High levels of education lead to low birth rates and small families due to: • Knowledge of birth control • Greater social awareness of the benefits of smaller families • Higher income and a desire for more material possessions

8. Religion • Muslim and catholic encourage large families • Traditionally oppose contraception hence high birth rates E.g. Algeria.

9. Social customs • UK average age for marriage is 30. • Woman follow careers for longer and delay children • In contrast Hindu culture traditionally marries girls at 16 and have 10 children! • In other cultures, polygamy encourages high birth rates. • In others the desire for a male heir results in large families to ensure at least one male survives.

10. Diet and health • High birth rates usually found in areas with poverty and poor diet. • Close correlation between high levels of mortality and fertility – leads to need for large families to ensure that some survive.

11. Politics • Population growth tends to be reversed by wars and the many who lose their lives limits population growth. • Baby booms e.g. Europe 1918-1920 and again 1946-1949 following the two world wars. • Population policies, some to increase some to decrease. • 1930s Germany – medals and grants to encourage high birth rates. • 20th century china one child policy

12. Factors affecting Mortality • Mortality tends to decrease with increasing levels of economic development. However there are a variety of factors that affect mortality and some relatively poor countries can have lower levels of mortality than in the UK and other developed countries.

13. Demographic structure • Countries with ageing populations have higher death rates E.g. UK retirement coastal resorts.

14. Medicine • Death rates lower with good access to medical care as measure by people per doctor

15. Social class • More affluent groups in societies tend to have lower death rates than poorer sections due to the latter’s: • Poor housing conditions • Inadequate clothing and diet • Inability to access or afford medical care • Employment in more difficult or dangerous occupations.

16. Place of residence • Death rates higher in urban areas than in countryside due to: • Crowded living conditions • High traffic densities • Atmospheric pollution • Nervous stress.