Population

Births and deaths are natural causes of population change. The difference between the birth rate and the death rate of a country or place is called the natural increase, and you calculate the natural increase by subtracting the death rate per 1000 population from the birth rate per 1000 population:

The rate of natural increase or growth rate of a population is given as a percentage, calculated by dividing the natural increase by 10.

If for example the birth rate / 1000 pop = 14, and the death rate / 1000 pop = 8, then

growth rate = 14 - 8 = 6 / 1000, or 0.6%.

	Population

	Global population growth
	At present, the world's population is growing fast - though this has not always been the case. Until the 1800s the world's population grew steadily but slowly for thousands of years. In 1820 the world's population reached one billion. 150 years later, in the early 1970s, the world's population reached three billion. In 1999, less than 30 years later, the population doubled to six billion. The global rate of population growth is now very fast (rising by about one billion every 15 years).

	World Population in 20th Century
	Population nearly quadrupled Highest population growth rate Largest annual population increase Shortest doubling time for population Sortest time to add 1 billion people Revolutionary declines in mortality Unprecedented declines in fertility Significant international migration Increased urbanization 1 billion: 1960 2 billion: 1985 3 billion: 2002 Great progress in women’s equality








	Causes and rates of change
	The population of any place changes over time. There are three main causes of population change: Births - usually measured using the birth rate (number of live births per 1000 of the population) Deaths - usually measured using the death rate (number of deaths per 1000 of the population) Migration - the movement of people in and out of an area
	Rate of change
	Births and deaths are natural causes of population change. The difference between the birth rate and the death rate of a country or place is called the natural increase, and you calculate the natural increase by subtracting the death rate per 1000 population from the birth rate per 1000 population: natural increase = birth rate - death rate. The rate of natural increase or growth rate of a population is given as a percentage, calculated by dividing the natural increase by 10. If for example the birth rate / 1000 pop = 14, and the death rate / 1000 pop = 8, then growth rate = 14 - 8 = 6 / 1000, or 0.6%.
	What Factors Affect Birth Rates ?
	Infant Mortality Government policies Child labour Social services Contraception & abortion Compulsory education Status and educational level of women Religion and culture Age structure
	What Factors affect Death Rates ?
	Public health care Medical care Wars Age structure Nutrition, diet and lifestyle
	What is migration?
	Migration is the movement of people from one place to another. There are many different types of migration. Internal migration is when people migrate within the same country or region - for example, moving from London to Plymouth. International migration is when people migrate from one country to another - for example, moving from Mexico to the USA.

	There are two key migration terms that you need to learn:
	Emigration is when someone leaves a country. Immigration is when someone enters a country.
	Voluntary or Forced Migration
	Voluntary Migration
	•This is when people move on their own free will. •Usually to find a better standard of living. •They are called economic migrants.
	Forced Migration
	•This is when people have no choice (they either move or face extreme hardship or even death). •This often happens after a natural disaster or war. •They are called refugees.

	Permanent or Temporary Migration
	Permanent Migration
	•This is when people move forever, to find a new place to live.
	Temporary Migration
	•This is when people don’t move forever, they always intend to go home at some point in the future.
	Migration Rate

	Push factors
	Push factors are the reasons why people leave an area, ie what pushes them away from their home. •lack of jobs, •low wages, •lack of services, •poor education •lack of safety, •high crime, •crop failure, •Drought and famine, •flooding, •poverty and war.
	Pull factors
	Pull factors are the reasons why people move to a particular area, ie what pulls them to a new place. •higher employment, •more wealth, •better services, •better health care, •better education, •good climate, •safer, less crime, •political stability, •more fertile land, •lower risk from natural hazards

	Problems facing LEDC cities
	Over 60% of Nairobi’s population live below the poverty line. Over 500 000 people live in Kibera which is a shanty town on the Southern edge of Nairobi opposite the Motoine River. A shanty town is a spontaneous settlement that is often built illegally on unused land along roadsides or on the edge of a city.

	Key things to know about population pyramids
	The shape of a population pyramid is very important and can tell us a lot about the people living in a particular country or place. The shape of a population pyramid gives us information about birth and death rates as well as life expectancy. A population pyramid tells us how many dependants there are living in an area. There are two groups of dependants; young dependants (aged below 15) and elderly dependants (aged over 65). Those of working age are classed as economically active. Dependants rely upon the economically active for economic support. Many LEDCs have a high number of young dependants, whilst many MEDCs have a growing number of elderly dependants.

	Population structure is usually shown using a population pyramid. A population pyramid can be drawn up for a whole country or an individual town, city or village.
	How may a pyramid change over time?
	A population pyramid that is very triangular (eg Mozambique in 2000) illustrates a population with a high number of young dependants and a low life expectancy. (fig. 1) A population pyramid that has fairly straight sides (more like a barrel) illustrates a population with a falling birth rate and a rising life expectancy. (figure 2) Over time, as a country develops, the shape of its population pyramid changes from a triangular shape to a barrel-like shape with straighter edges. Places that are experiencing an ageing population and a very low birth rate may have a population structure that looks a little like an upside-down pyramid.