S2 Geography Unit 1: Population Theories

• S2 Geography is studying population in Unit 1.

Malthusian Theory

• The global population will increase geometrically.
• Food resources for the population will increase arithmetically.
• Potential dangers of overpopulation are highlighted.
• Uncontrolled human populations increase faster than food supplies.
• Human populations will eventually exceed food sources.
• Natural events like famine or disease could cause population crashes.

Population Explosion

• Represented by a line graph showing rapid global population growth.
• A trend upward suggests a gradual increase.
• The steepest portion indicates the fastest growth rate.

Population Growth

• Population change can be positive or negative.
• Zero population growth exists when there is no population change.
• Population growth is uneven worldwide.
• The Natural Population Change is calculated as Birth Rate (BR) minus Death Rate (DR).
• Overall Population Change is (BR-DR) + the effect of migration.
• Natural Increase/Decrease, or Natural Population Change, are alternative names for this.

Vital Rates

• Birth Rate is the number of live births per 1,000 people annually.
• Death Rate is the number of deaths per 1,000 people annually.
• Natural Increase/Decrease occurs when the birth rate is more or less than the death rate.
• Infant Mortality Rate is the number of deaths of children under one year old per 1,000 live births.

DTM: Demographic Transition Model

• A temporal model which looks at population change over time.
• It examines the impact of birth and death rates on the total population of a country.

Stage 1: High Stationary

• Pre-industrial, with total population low due to high birth and death rates
• High birth rate caused by reliance on agriculture/manual labor, leading to larger families for a larger workforce.
• Stable replacement level maintenance is sought.
• High death rate is due to high infant mortality and low life expectancy.
• Limited medicine and maternal care causes high infant mortality rates.
• Inadequate sanitation and public health causes low life expectancy.
• Total population is relatively constant.

Stage 2: Early Expanding

• Early industrialization leads to a rapid fall in death rate.
• Birth rate remains high.
• Health improvements especially in pediatric care, which is an important factor in childhood life expectancy.
• Death rates decrease with improved healthcare, education and sanitation.
• Total population rises as births exceed deaths.

Stage 3: Late Expanding

• Death rates are low and birth rates decrease.
• Improved economy, the increase in women's status and increased access to contraception all result in lower birth and death rates.
• Slower total population growth continues until birth rates reach or fall below the replacement level (2.1 births per woman).

Stage 4: Low Stationary

• Industrialized, developed society with both birth and death rates low.
• Strong economies, a highly educated population, and ample healthcare systems result in a decreased birth and death rate.
• The total population is high with a gradual or stable growth rate.

Stage 5: Declining?

• Death rate surpasses the birth rate.
• Economic forces reduce family size and encourage contraception use.
• Birth rates fall as a result of high living costs or enticing job prospects, resulting in birth rates being below the replacement level of 2.1 children per woman.
• An aging population leads to eventual population declines.

Application of the DTM

• Most less economically developed countries are in stage 2 or 3, with a growing population and high natural increase.
• Most more economically developed countries are in stage 4, and some are already in stage 5.

What is DTM based on?

• The model is based on observations of developed countries in the 18th and 19th centuries.

Usefulness of DTMs

• Useful as a framework to measure, evaluate, and understand reality
• A model is a depiction of a real-world phenomena to facilitate understanding it.
• A simplified, generalized version of real-world events, removing incidental details.

Distributions

• Describes distribution of areas that are sparsely/densely populated.
• Sparsely/densely concentrated mostly in the overall pattern with concentrations in specific patterns.

Population Distribution

• Spatial distribution is global population distribution.
• Population density is the number of people per unit of land.
• The formula for population density is (# of People) / Area.
• High density = 200-1000+ persons/km squared.
• Moderate density = 10-199 persons/km squared.
• Low density = 0-9 persons/km squared.
• Look for patterns on a global scale like near the equator or the tropics.
• Cardinal directions and world regions create specific patterns, e.g. northern South America.

Factors Affecting Population Distribution

• These include physical environment factors.

Climate Factors

• Rainfall and temperature over time that affect living conditions and agriculture.
• Extreme temperatures repel settlement.
• Agriculture provides food, which is a basic necessity for a living condition.
• No agriculture causes no basic necessity, in turn not a suitable environment.

Relief Factors

• Relief refers to height and gradient which affect drainage and agriculture.
• Steep slopes, unless terraced, are unsuitable for crop growing and lower population density.
• Mountainous, less-accessible regions have low population density.
• Population densities may be higher if relief is higher for safety.
• Flat land is easy to build on and retains water to grow crops.

Soil Factors

• Poor soils affect cultivation, lowering population density specifically in agricultural societies.
• Ganges-Brahmaputra delta and Mekong River delta soils are fertile, leading to high population density.

Resource Factors

• Include water, materials for shelter, food, and minerals which are basic needs.
• Population density lowers without these unless mitigated by technology.

Technology Factors

• Refers to the skills, knowledge and tools to meet needs.
• With technological advances, environments that were previously unsuitable are converted.
• Water can be piped into the desert for living.