Geography 1.1 Population Dynamics

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Population Dynamics

The Rapid Increase Of The World's Population

During most of the early period in which humankind first evolved, global populations very low, reaching perhaps some 125 000 people a million years ago.

Ten thousand years ago, when people first began to domesticate animals and cultivate crops, world population was no more than 5 million. Known as the Neolithic Revolution, this period of economic change significantly altered the relationship between people and their environments. But even then the average annual growth rate was less than 0.1 per cent per year.

However, as a result of technological advance the carrying capacity of the land improved and population increased. The carrying capacity in an environment is the maximum population that the environment can sustain and give food, habitat, water and other necessities available in the environment.

Demographers (people who study human populations) estimate that world population reached 500 million by about 1650. From this time, population grew at an increasing rate. By 1800, global population had doubled to reach one billion.

In 2011, the population was 7 billion. It took 12 years for world population to increase from 6 to 7 billion, the same time span for the previous billion to be added. It is estimated that population will increase to 8 billion by 2023.

The total population and the rate of population growth are much higher in less economically developed countries than more developed countries. The bulk of population increase is in the developing countries, where the number of birth exceeds the number of deaths.

Demographic Momentum

It is no. of maturing youth added each year,which remains very high.This is because there are so many woman in child bearing age.The demographic transformation which took a century to complete in the developed countries,has occurred in a single generation in some less developed countries.

Demographic divide

A demographic divide is the vast gulf in birth and death rates among the world's countries.There is an increase in population growth in many countries whereas there is a fall in population ratio in some countries.

These diverging trends have created a demographic divide between countries,where population growth is high and low.

Cause of change in population size

Population change in a country is affected by...

1. The difference between births and deaths. This is natural change.

(i) Birth Rate

It is defined as the number of births per thousand population in a year.

(ii) Death Rate

It is the number of deaths per thousand population in a year.

If it is positive, it is referred to as natural increase.

If it is negative, it is known as natural decrease.

2.

(i) Immigration rate

The immigration rate is the number of immigrants per thousand of the population entering a country per year.

(ii) Emigration rate

This is the number of emigrants per 1000 of the population leaving their country of origin in a year.

The balance between immigration and emigration is net change.

The Demographic Transition Model

The demographic transition model helps to explain the causes of a change in population size.

Demographic transition is the historical shift of birth and death rates from high to low levels in a population.

A model is a simplification of reality, helping us to understand the most important aspects of a process.

The High Stationary Stage (Stage 1)

The birth rate is high and stable while the death rate is high and fluctuating due to famine, disease and war at times. Society is pre-industrial with most people living in rural areas, dependent on subsistence agriculture. Infant mortality is high and life expectancy is low. A high proportion of the population is under the age of 15. This stage belongs to remote societies like tribal and rural people.

The Early Expanding Stage (Stage 2)

The death rate declines to levels never before experienced. The birth rate remains at its previous level because the social norms governing fertility take time to change. As the gap between the two vital rates widens, the rate of natural change increases to a peak at the end of this stage. The infant mortality rate falls and life expectancy increases. The proportion of the population under 15 increases. The main reasons for the decline in the death rate are: better nutrition; improved public health particularly in terms of clean water supply and efficient sewage systems; and medical advances. Considerable rural-to-urban migration occurs during this stage.

The Late Expanding Stage (Stage 3)

After a period of time social norms adjust to the lower level of mortality and the birth rate begins to decline. Urbanisation generally slows and the average age increases. Life expectancy continues to increase and infant mortality decreases. Countries in this stage usually experience lower death rates than nations in the final stage due to their relatively young population structures.

The Low Stationary Stage (Stage 4)

Both birth and death rates are low. The former is generally slightly higher, fluctuating somewhat due to changing economic conditions. Population growth is slow. Death rates rise slightly as the average age of the population increases. However, life expectancy still improves as age-specific mortality rates continue to fall.

The Natural Decrease Stage (Stage 5)

In a limited but increasing number of countries, mainly European, the birth rate has fallen below the death rate. In the absence of net migration inflows these populations are declining. Examples of natural decrease include Germany, Belarus, Bulgaria and Ukraine.

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Reasons for contrasting rates of population change

Population change is governed by three factors: fertility, mortality and migration. This section examines the influences on fertility and mortality Fertility is linked with birth rate. The total fertility rate is the average number of children a woman has during her life time.

The Factors Affecting Fertility

Demographic: Other population factors, particularly mortality (death) rates, influence fertility. When infant mortality is high, it is usual for many children to die before reaching adult life. In such societies, parents often have many children to compensate for these expected deaths. The infant mortality rate is the number of deaths of children under one year of age per thousand....... The continent with the lowest fertility is Europe and the highest is Africa.

Social/ Cultural: In some societies, particularly in Africa, tradition demands high rates of reproduction. Here the opinion of women in the reproductive years may have little influence weighed against intense cultural expectations. Education, especially female literacy, is the key to lower fertility, because the knowledge of birth control, greater social awareness, opportunity for employment, attitudes about abortion and the labor value of children. In some countries religion oppose artificial birth control.

Economic: Fertility rates tend to be highest in the world's least developed countries. Many of the least developed countries' children are seen as an economic asset because of the work they do, often on very small farms, and also because of the support they are expected give their parents in old age. In many poor countries there is little or no government support for elderly people. In the developed world the general perception reversed and the cost of the child dependency years is a major factor in the decision to begin or extend a family. Economic growth allows greater spending on health, housing, nutrition and education, an increase in the average age of marriage leads to a fall in the birth rate.

Political: Some governments try to change fertility rates to reduce population growth by government policies like family planning measures, use of contraceptives and more. However, countries like Russia, where the birth rate has fallen below the death rate, want to increase their population.

The Factors Affecting Mortality

Death rates are affected by disease, war, medical technology, improved health care, transportation development and nutrition.

Life Expectancy At Birth: It is the average number of years a new born infant can expect to live under current mortality levels. Each country has a different life expectancy rate. The cause of death varies significantly between developed and developing worlds.

Social and Economic Factors:

poverty

poor access to healthcare

antibiotic resistance

changing human migration patterns

new infectious agents.

Factors Responsible For HIV/AIDS:

poverty and social instability that result in family disruption

high levels of other sexually transmitted infections

the low status of women

sexual violence

high mobility, which is mainly linked to migratory labor systems

ineffective leadership during critical periods in the epidemic's spread.

The Impacts of HIV/AIDS:

Labor supply - economically active population reduces as more people fall sick and are unable to work. This can have a severe impact on development. In the worst affected countries the epidemic has already reversed many of the development achievements of recent decades. In agriculture,food security is threatened as there are fewer people able to farm and to pass on their skills.

Dependency ratio - those who contract HIV are mainly in the economically active population. An increasing death rate in this age group increases the dependency ratio.

Family - AIDS is impoverishing entire families and many children and old people have to take on the role or carers. Adult deaths, especially of parents, often causes households to be dissolved. The large number of orphaned children in some areas puts a considerable strain on local communities and one the government in developing countries.

Education - with limited investment in education many young people are still unaware about how to avoid the risk of contracting HIV/AIDS. In addition there are a considerable number of teachers who have AIDS and are too ill to work. UNICEF has stressed how the loss of a significant number of teachers is a serious blow to the future development of low-income countries.

Poverty - there is a vicious cycle between AIDS and poverty. AIDS prevents development and increases the impact of poverty. Poverty worsens the AIDS situation due to economic burdens such as debt repayments and drug/medical costs.

Infant and child mortality- mortality rates increase as AIDS can be passed on from mother to child.

Immigration

The number of people moving into a country. Pull factors attract people into a country (for e.g. higher wages, better standard of living, good education facilities, better health facilities and safety and secured environment).

Emigration

The number of people leaving a country. Push factors make people want to move out of a country (for e.g conflict, war, drought, famine, unemployment problem, natural disasters, lack of security and extreme religious activity). Refugees who are forced to leave their country move due to the problems listed above, mainly war.

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Population Terms

Population Explosion: It is rapid growth of population.

Population Policy: The measures taken by the government either to influence or reduce population growth. They may promote large families, immigration to increase population, or encourage fewer births. Many countries control their fertility rate to reduce population growth. They introduce family planning programs.

Under-population

If the actual population in a country is less than the optimum or ideal population, there will not be enough people to exploit all the resources of the country fully. Thus, the population and the per capita income will be lower.

-When the population is too small to exploit the country’s resources with maximum efficiency.

Over-population

If the actual population is above the level of optimum population, there will be too many people to work efficiently and produce the maximum goods and the highest per capita income. As a result, the per capita income becomes poorer than before. The population is more than the resources available. The land per capita is low. When the population is too large and the efficiency falls to give only a subsistence income to the labor force.

Optimum Population

Optimum population uses the available resources to give itself the maximum income. At first the increasing population exploits a country’s resources to the maximum and average standard of living rises.

Evidence Of Over-Population:

One-quarter of the world's children have protein-energy malnutrition.

The long-term trend for grain production per person is falling.

About 40 per cent of agricultural land is moderately degraded and 9 per cent is highly degraded

Water scarcity already affects every continent and 4 of every 10 people in the world.

A quarter of all fish stocks are over-harvested.

There are concerns that global peak oil production will come as early as the next decade.

Intense competition for land.

Heavy traffic congestion.

High house prices.

High environmental impact of economic activity.

Pressure on water resources.