APHUG UNIT 2 - HEIMLER

Population distribution: how people are spread over a given area
Population density: number of people per unit area
- Arithmetic density = total number of people / total land area
- Physiological density = number of people / area of arable (farmable) land
- Agricultural density = number of farmers / arable land area
Patterns / scales: density and distribution differ by local, regional, global scales
Consequences of density / distribution (Topic 2)
- Overcrowding, stress on infrastructure
- Uneven resource use
- Environmental degradation
- Political consequences (representation, urban planning)
- Carrying capacity debates: how many people Earth or a region can sustainably support

Population composition: the makeup of a population (age, sex, etc.)
Population pyramids: graphical representation of age-sex structure
- Wide base = many young people (high birth rate)
- Narrow top = fewer older people (high death rate / low life expectancy)
- Shape changes through stages of development
Dependency ratio: ratio of dependents (young + old) to working-age population

Crude Birth Rate (CBR): births per 1,000 people per year
Crude Death Rate (CDR): deaths per 1,000 people per year
Rate of Natural Increase (RNI / NIR) = CBR − CDR (expressed per 1,000 or as a percent)
Population doubling time: how long it takes for a population to double (if constant rate)
Factors influencing growth / decline
- Health care, sanitation, medical advances
- Nutrition, food supply
- Cultural norms, religion, education
- Government policies

DTM: model of how population growth changes as societies industrialize
- Stage 1: High birth, high death → low growth
- Stage 2: Death rate falls, birth rate stays high → rapid growth
- Stage 3: Birth rate declines → growth slows
- Stage 4: Low birth, low death → stable or slow growth
- Stage 5 (sometimes): Birth rate below replacement → population decline
ETM: tracks changes in disease / death causes over time
- Early: pandemics / infectious diseases dominate
- Later: degenerative / chronic diseases dominate (heart disease, cancer, etc.)
- Matches transitions in DTM

Malthusian Theory (Thomas Malthus):
- Population grows geometrically, food supply grows arithmetically → eventual crisis
- Checks: famine, disease, war
Critiques / counter-theories:
- Technological advances (Green Revolution etc.) can increase food supply
- Social changes: family planning, education, empowerment of women
- Some argue population growth can drive innovation and economic growth

Pronatalist policies: encourage more births (e.g., incentives, subsidies, leave policies)
Antinatalist policies: discourage high fertility (e.g., one-child policies, family planning programs)
Governments adopt policies based on overpopulation or underpopulation risks

Types of migration
- Internal (within country) vs International
- Voluntary vs Forced
- Other forms: chain migration, step migration, guest workers, transhumance, etc.
Push and pull factors (Topic: Causes of Migration)
- Push: unfavorable conditions that drive people away (conflict, famine, unemployment)
- Pull: favorable conditions that attract people (jobs, stability, safety)
- Categories: economic, social / cultural, political, environmental, demographic
Effects / consequences of migration
- Economic: remittances, labor markets, brain drain / gain
- Social: cultural diffusion, assimilation, conflicts
- Political: immigration policies, border issues, citizenship debates
- Demographic: population redistribution, density changes

Aging population effects:
- Higher dependency ratio (more elderly dependents)
- Increased costs for healthcare, pensions, social services
- Shrinking workforce → fewer people paying taxes / supporting elderly
- Potential labor shortages, economic stagnation
Responses: encouraging higher fertility, immigration, extending retirement age