Presentation on theme: "How and why do populations change naturally?. Following a study of changes in birth and death rates in several developed countries in north America and."— Presentation transcript:
How and why do populations change naturally?
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.
Birth rate per 1000 population Death rate per 1000 population Rate of natural increase (%) Burkina Faso Liberia Somalia Zimbabwe Gabon Namibia Finland France Malta980.2 Germany Italy Hungary Data to plot on graph
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.
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….
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
Religion Muslim and catholic encourage large families Traditionally oppose contraception hence high birth rates E.g. Algeria.
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.
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.
Politics Population growth tends to be reversed by wars and the many who lose their lives limits population growth. Baby booms e.g. Europe and again following the two world wars. Population policies, some to increase some to decrease. 1930s Germany – medals and grants to encourage high birth rates. 20 th century china one child policy
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.
Demographic structure Countries with ageing populations have higher death rates E.g. UK retirement coastal resorts.
Medicine Death rates lower with good access to medical care as measure by people per doctor
Social class More affluent groups in societies tend to have lower death rates than poorer sections due to the latters: Poor housing conditions Inadequate clothing and diet Inability to access or afford medical care Employment in more difficult or dangerous occupations.
Place of residence Death rates higher in urban areas than in countryside due to: Crowded living conditions High traffic densities Atmospheric pollution Nervous stress.