Population Change

Population can change in both size and structure. In fact it is doing so all the time; this is known as ‘Dynamism’ – a process of change.

Population dynamics (size)

Natural Change: A population is increased by more births and reduced by more deaths. The size of a country’s population at any one time can be thought of as the respective balance between these two variables. More births than deaths, and the population rises; more deaths than births and the population falls. These are sometimes referred to as net surplus/net deficit and provide the ‘natural rate of increase/decrease’.

Actual Change: Very few populations exist in isolation; most have people migrating to and from the country. If there are more immigrants than emigrants, this leads to a net migration surplus; if more emigrants than immigrants – a net migration deficit. The change in the total population is, therefore, the outcome of all these changing demographic factors: births, deaths, in-migrants and out-migrants. The resultant change is known as ‘Gross population change’ or ‘Actual change in population’.

Population dynamics (structure)

Population structure can be thought of as the individual components that make up the population. Typically geography considers the following:

Age structure: The proportion of people in different age-groups. Developing countries typically have high proportions of young people whilst Developed countries are experiencing increasing proportions of elderly people. Both these groups may depend on the working-adult population for their care or via the taxes they may pay. This leads to the concept of the ‘Dependency Ratio’: the balance between those in the ‘young dependent’ population (0-16 yrs) plus the ‘elderly dependent population (65+ yrs), versus those in the ‘economically active population’ (17-64 yrs).

Gender structure: The gender balance within a population. Whilst you may imagine that most countries will be roughly 50:50 between male and female, migration may be predominant amongst one gender group than another – both out-migration and in-migration – and this will impact on the gender mix in the countries of origin and destination. Similarly, political impacts – such as war – can have a major impact on the gender mix, either because of casualties or the resulting fleeing refugees.

Fertility structure: The combined effect of age and gender variables can affect the fertility structure of a population. This is the proportion of women of child-bearing age within a population. In places with widespread use of birth control this has a reduced impact than in previous times but in many countries, the percentage of women of child-bearing age is an indication of likely birth rates.

Affluence structure: The degree of similarity in wealth-distribution amongst the population versus wealth-inequality. The Gini Coefficient is a measure of wealth inequality amongst nations and indicates those with very large gaps between the richest and poorest, and those where there is a more even distribution of wealth.

Ethnic structure: The ethnic composition of a population. Some populations are ethnically very mixed (USA) whilst others are relatively homogenous (Japan). The degree of ethnic composition is usually a result of historical factors, political factors and recent migration rates and sources. An ethnically mixed population may have been so for many decades, if not centuries, with multi-generational descendants of original migrants, or it may have recently developed as such with original migrants and their first-generation children.

This is not an exhaustive list of ‘structural variables’ – you could consider a population from a wide range of variables (such as ‘language structure’, ‘employment structure’…..etc.), but it is the dominant shares of these main features that usually distinguish one population from another in demographic terms.