8.1 Human Population Dynamics

Question 1

What is the carrying capacity of Earth for humans?

Answer 1

Because we are the only species that can significantly change our environment, we don’t know our carrying capacity.
This is because of discovering new technologies we can increase our carrying capacity.

Question 2

What may limit population size?

Answer 2

• Availability of food and water
• Invasion of parasites, pathogens and disease
• Over crowding
• Severe or sudden climate change
• Pollution of air, water and soil

Question 3

Why is the population growth slowing down?

Answer 3

• Global birth rate is falling
• Improvements in basic education and female literacy cause a reduction in desired family size
• Increased international migration to the more economically developed countries where people have fewer children
• Diseases such as AIDS and malaria

Question 4

In which countries is the increase in population happening the fastest?

Answer 4

• Greatest increase is in developing countries (HIGH birth rates)
• Family planning is not always available
• More difficult access to contraceptives
• Little education
• Socially big families are deemed normal

Question 5

Why is there concern about the predicted population growth?

Answer 5

• Key resources are becoming limiting in some regions
• Capacity of environment to absorb our waste products may be exceeded
• Growing inequality between rich and poor
• Growing number of environmental refugees

Question 6

What is Thomas Malthus’ population theory?

Answer 6

Thomas Malthus believed populations increased geometrically, whilst food production increased in an arithmetic progression. This would leave a difference resulting in the want of food and famine, unless birth rates decreased.

Question 7

What are “positive checks” in Thomas Malthus’ population theory?

Answer 7

Population could exceed food supply only to be positively “checked” (reduced) by famine, war, and disease

Question 8

What are “negative checks” in Thomas Malthus’ population theory?

Answer 8

Negative checks refer to the population that can pre-empt food shortages and as a result slow their population growth to keep it withing the limits of the food supply. These negative checks include marriages and abstinence from sex. (this was written BEFORE the wide spread distribution of contraceptives).

Question 9

What is Ester Boserups’ population theory?

Answer 9

Ester Boserup concludes that technical, economic and social changes are unlikely to take place unless the community concerned is exposed to the pressure of population growth.

(So when a population faces pressure due to food shortages, they will improve technology and find ways to increase food supply)

Question 10

What are the 4 main factors that affect the population size of organisms?

Answer 10

• Birth Rate
• Death rate
• Immigration
• Emigration

Question 11

What is “Crude Birth Rate”?

Answer 11

“number of births per thousand individuals in a population per year”

(total number of births / population size) x 1000
CBR for world = 18.7 births per 1000 population

Question 12

What is “Crude Death Rate”?

Answer 12

“number of deaths per thousand individuals in a population per year”

(total number of deaths/ population size) x 1000
CDR for world = 7.9 deaths per 1000 population

Question 13

What is “Natural Increase”?

Answer 13

“Rate of human growth expressed as a % change per year”

( Crude birth rate - Crude death rate ) / 10

Question 14

What is “Doubling Time”?

Answer 14

“Time in years for a population to double in size assuming natural growth rate remains constant”

( 70/ percentage growth rate )

Question 15

What is “Total Fertility Rate”?

Answer 15

“Average number of children each woman has over her lifetime”

Fertility > 2 means population size is increasing
Fertility < 2 means population decreases
Fertility = 2 means stable populations
–> WITHOUT taking migration into account

Question 16

What is “Fertility Rate”?

Answer 16

“Number of births per 1000 women of child-bearing age”

Question 17

What does the base of a population pyramid show?

Answer 17

1. If wide –> Many children (high birth rate)

2. If narrow –> Less children (low birth rate)

Question 18

What does the top of a population pyramid show?

Answer 18

1. If high and wide –> Many old people (high life expectancy)
2. If narrow and pointy –> Low life expectancy

Question 19

What is the country like if it the population pyramid is triangle shaped?

Answer 19

Likely to be for a developing country. The rapid decrease in numbers to form a triangular shaped pyramid, means that there must also be a fairly high DR. Concave slopes characterise high death rates.

Question 20

What is the country like if it the population pyramid is more straight shaped (Oval-like)?

Answer 20

If it is more straight up and down, it is likely to be for a more developed country. There are likely to be similar numbers of people in all the bands up until 70, when the numbers will start to fall. Straight or near vertical sides characterise a low death rate.

Question 21

What is the country like if it there is a bulge in the middle of the population pyramid?

Answer 21

Bulges in the slope suggest high rates of immigration or in-migration (for instance, excess males 20-35 years will be economic migrants looking for work; excess elderly, usually female, will indicate retirement resorts).

Question 22

What does the “Demographic Transition Model” show?

Answer 22

DTM- Demographic transition model shows us that countries progress through recognized stages in the transition from LEDC to MEDC. It suggests that death rates fall before birth rates and that the total population expands.

Question 23

What is Stage 1 of the “Demographic Transition Model”?

Answer 23

Stage 1 - High Fluctuating:
Societies where there is little medicine, low life expectancy and no means of birth control. Remote rainforest areas of Amazonia and Indonesia are the only locations where this stage might happen today.

Question 24

What is Stage 2 of the “Demographic Transition Model”?

Answer 24

Stage 2 - Early Expanding:
Key factor that indicates the change from Stage 1 to Stage 2 is a decrease in death rate. Improvements in medicine and hygiene cure some diseases and prevent others. Life expectancy increases.

Question 25

What is Stage 3 of the “Demographic Transition Model”?

Answer 25

Stage 3 - Late Expanding:
Death rate continues to fall, but more slowly. The key factor at the start of Stage 3 is a decrease in birth rate, which is often quite rapid. This is due to both the availability of birth control and economic changes, which mean people benefit from having smaller families. As a country develops children become economic costs instead of economic assets. In other words, they cost the family more than earning it.

Question 26

What is Stage 4 of the “Demographic Transition Model”?

Answer 26

Stage 4 - Low Fluctuating:
Birth and death rates are both low. The lines on the graph are close to each other and birth rate varies according to the economic situation. When the economy is growing and people have jobs and earn a good living, they are more likely to afford children.

Question 27

What is Stage 5 of the “Demographic Transition Model”?

Answer 27

Stage 5 - Natural Decrease:
Many eastern and a few western European countries are at stage 5 for different reasons. The UK remains at stage 4. Death rate rises because the population includes more elderly people. Many young woman can access career opportunities and therefore they are more likely to postpone motherhood. Therefore birth rate dips below death rate and there is a natural decrease in the population.

Question 28

What are some advantages of using models to predict human population change?

Answer 28

• Shows relationship between DTM and economic development.
• Timescale of each stage is flexible
• Provides a starting point to demographic change over time
• Allows comparisons to be made between countries
• Easy to understand

Question 29

What are some disadvantages of using models to predict human population change?

Answer 29

• Model only takes birth and death rate into a count (not migration)
• Models don’t take future catastrophes into a count
• Quality of predictions is based on quality and frequency of the data
• The DTM is based on the observation of western development. It assumes today’s countries will all develop in the same way.
• Western countries had access to colonies, current developing countries do not

Question 30

What are the two types of direct policies a government can introduce (connected to population changes)?

Answer 30

1. Pro-Natalist policies

2. Anti-Natalist policies

Question 31

What are Pro-Natalist policies?

Answer 31

Pro-Natalist policies are put in place to increase the birth rate. They encourage families to have more children by offering them tax and welfare incentives.

These policies are often not so effective however, as it is difficult to convince people to change their lives.

Question 32

What are Anti-Natalist policies?

Answer 32

Anti-natalist policies are put in place to decrease the birth rate. They encourage families to have less children by giving them tax and welfare disincentives, raise awareness of how to reduce fertility and emancipating women.