Global Population Dynamics: Trends and Structures
1. Population Evolution
In the early 21st century, Earth’s population exceeded 6 billion. The Neolithic domestication of animals and agriculture led to increased food production, consequently boosting population growth. Since the 19th century, European population growth surged due to healthcare advancements and economic development. The 20th century witnessed a population explosion, with slower growth in wealthier countries and steady increases in poorer nations.
2. Global Population Distribution
2.1 Population Density
Population density is the ratio between a population and the space it occupies, calculated by dividing the number of inhabitants by the area. Territories with less than 1 inhabitant per square kilometer are considered uninhabited, while over 100 inhabitants per square kilometer signifies high density. Density varies due to climate, resources, and wealth. Warmer, temperate regions are more populated than colder areas. Imbalances between population and resources lead to poverty, hunger, and migration.
3. Natural Population Movements
3.1 Birth Rate
The birth rate is the number of births in a population over one year, calculated by dividing the number of births by the total population and multiplying by 1,000. Fertility measures the number of children per woman of childbearing age (15-49 years). A rate of 2.1 children per woman is needed to maintain population levels. The Total Fertility Rate (TFR) is calculated by dividing the number of live births in a year by the number of women of childbearing age and multiplying by 1,000.
3.2 Mortality
Mortality is the number of deaths in a population over one year.
- Mortality Rate (MR): Calculated by dividing the number of deaths in a year by the total population and multiplying by 1,000, expressed per mil.
- Infant Mortality Rate (IMR): Calculated by dividing the number of deaths of infants under one year old by the number of registered births in the same period and multiplying by 1,000, expressed per mil.
3.3 Natural Growth
Natural increase is the difference between births and deaths in a population. Positive growth occurs when births exceed deaths, while negative growth occurs when deaths exceed births. The Natural Growth Rate (NGR) is the difference between the birth rate and mortality rate, or the natural growth divided by the total population multiplied by 100.
3.4 Demographic Transition Model
The demographic transition model explains population evolution through phases:
- Original Phase: Low birth and mortality rates, low population growth.
- Transition Phase: (19th century) Birth rate declines, mortality remains high. (Late 20th century) Both birth and death rates decrease, reducing natural growth.
- Evolved Phase: Very low birth and mortality rates, minimal natural growth (late 20th century).
- Regression Phase: Low birth rate, increased death rate due to aging population, weak or negative natural growth.
Not all countries follow this model uniformly.
4. Spatial Movements
Normal Movements
These movements are regular and do not involve a change of job or residence, occurring between nearby or distant places.
- Pendulum Movements: Commuting for work or study.
- Leisure-related Movements: Weekend trips, holidays, and vacations.
Migratory Movements
These involve a change of work and residence.
- Emigration: Movement of people from a particular area.
- Immigration: Inflow of people to a specific area.
- Net Migration: The difference between emigrants and immigrants in a specific place.
5. Population Structure
Age Structure
- Youth: 0-14 years
- Adults: 15-64 years
- Elderly: 65 years and over
Sex Structure
The global population has unequal numbers of men and women. More boys are born than girls, but female life expectancy is higher.
Work Activity Structure
- Active Population: People of working age who are employed, unemployed, or seeking work.
- Inactive Population: Those unable to work (minors, retirees) or not engaged in paid work (homemakers, students).
Educational Attainment Structure
Population can be classified by literacy rate, reflecting the percentage of people aged 15 and over who can read and write.
6. Population in Spain
6.2 Natural Movement of the Spanish Population
Birth Rate
Since 1980, Spain’s birth rate has dropped due to:
- Increased age at marriage.
- Increased female workforce participation.
- Rise in single-person households.
Mortality
Mortality in Spain is low but has slightly increased due to population aging. There are gender differences in mortality, with increased mortality among young people due to traffic accidents. The “three Cs” are currently the most common causes. Infant mortality has declined.
Natural Growth
Currently, Spain has very low birth and mortality rates, resulting in minimal natural growth.
6.3 Migratory Movements in Spain
Internal Migration
- Rural exodus is weak.
- High percentage of population moving to city suburbs.
- Coastal areas attract retirees.
External Migration
Spain has become a host country for immigrants seeking better living conditions.