enviromental science

FAQs: Human Population Growth & Phases

Question 1: What are the causes of the human population explosion?

Answer 1: Prior to the 1800s, diseases like smallpox, diphtheria, measles, scarlet

fever, bubonic plague, typhus, and cholera kept the human population in equilibrium.

In the 1800s, scientists discovered how many of these diseases were spread and were

able to develop counter measures. The discovery of penicillin and other antibiotic

drugs in the 20th century resulted in a further decline in the human mortality rate.

Improvements in sanitation and agriculture, notably the Green Revolution of the 1960s

and 70s, further contributed to the population explosion.

Question 2: Where is the most rapid growth in population taking place? What are

some of the social and environmental consequences of this growth?

Answer 2: The most rapid population growth is taking place in the developing

countries. One result is that over a billion people live in households that have too little

land to meet their basic needs for food and fuel. Overuse of available resources,

notably wood for fuel, have caused erosion, desertification and decreased food

production. Consequently, many rural residents have migrated to the cities, causing a

dramatic rise in urban populations around the world. Many new arrivals have been

forced to live in areas that lack basic sanitation. Other social consequences include an

increased demand for social services, education, and jobs. Political instability often

results when these demands are not met.

Question 3: What is meant by demographic transition?

Answer 3: The basic premise of demographic transition is the decline of birth and

death rates as a society modernizes. The transition consists of the following four

phases:

1. The first phase of the transition is characterized by high birth and high death rates.

2. The second phase is characterized by a declining death rate (usually due to improvements in medical care) but no corresponding decline in the birth rate.

This is a phase of accelerating population growth.

3. The third phase is characterized by declining fertility rates. 4. The fourth and final phase is reached when the birth rates and death rates reach

relative equilibrium. At this point, the population is stable.

The developed nations are considered to be in phase four, while the developing nations

are in phases two and three.

Question 4: Must a society modernize for the fertility rate to stabilize?

Answer 4: This question has been debated for almost 200 years. One school of thought

holds that countries must adopt policies restricting family size or make birth control

readily available. A second school of thought holds that if a country concentrates its

efforts on development, then the birth rate will naturally decline as it has in the

developed nations.

Question 5: Why do families in developing nations tend to be much larger than

families in developed nations?

Answer 5:

In many countries, large families are viewed as a form of social security. The

more children there are in a family, the greater will be the likelihood the parents

will enjoy security in their old age.

Families tend to be large in countries where the child mortality rates are high. If

parents expect that a certain percentage of their children will die, they are likely

to have larger families.

Children are a source of low-cost labor in many developing nations. In

developed nations, on the other hand, children are considered to be more of an

economic liability.

Women in many developing nations have few opportunities to work outside

their homes.

Access to contraceptives is limited in many developing countries, especially in

rural areas.