CHAPTER 6: HUMAN POPULATIONS,

DEMOGRAPHY AS AN
ENVIRONMENTAL ISSUES

BY: GROUP 6
 HUMAN
POPULATION
HISTORY
Malthusian Checks on Population
by: Justimbaste, Harley
01. HUMAN POPULATION HISTORY

02. MALTHUSIAN THEORY OF

POPULATION

03. MALTHUSIAN CHECKS ON

POPULATION

04. CRITICISM OF MALTHUSIAN

THEORY OF POPULATION TABLE OF
CONTENT
HUMAN POPULATION
HISTORY
Agricultural Revolution (c. 10,000 BCE - 1,500 CE)
Agricultural Advancements: Around 10,000 BCE,
humans began to develop agriculture, domesticating
plants and animals. This shift allowed for more stable
food supplies and sedentary communities.
Population Growth: As people settled, populations
began to grow. The development of civilizations (e.g., in
Mesopotamia, Egypt, India, and China) allowed for
denser populations. By the start of the Common Era (1
CE), the global population was estimated at 5-10
million.
Challenges: Diseases, famines, and conflicts still kept
population growth relatively slow and cyclical.
Pre-Industrial Era (1,500 - 1800)
Incremental Growth: From the 16th century onward,
improved agricultural practices, trade, and early forms
of industry supported larger populations, especially in
Europe and parts of Asia.
Global Expansion: Explorations and colonizations
spread populations globally, often leading to declines
among indigenous groups due to diseases.
Population Estimate: By 1800, the world population
reached approximately 1 billion.
HUMAN POPULATION
HISTORY
Industrial Revolution (1800 - 1950)
Rapid Growth: Technological advancements in
agriculture, sanitation, and medicine drastically
reduced death rates, especially in industrialized
nations.
Urbanization: People moved to cities for jobs, fueling
urban population growth.
Medical Advancements: Vaccinations and improved
public health measures contributed to lower mortality
rates. The global population more than doubled,
reaching about 2.5 billion by 1950.
Modern Era (1950 - Present)
Population Explosion: After WWII, the world saw
unprecedented population growth, especially in
developing countries, due to continued advances in
medicine, public health, and food production (Green
Revolution).
Peak Growth Rate: In the 1960s, the global population
growth rate peaked, with over 2% annual growth.
Urbanization and Aging: More people live in urban
areas than rural, and populations in many countries are
aging, leading to economic and social challenges.
MALTHUSIAN THEORY
OF POPULATION
The Malthusian Theory of Population
involves arithmetic food supply
growth and exponential population
growth. This theory was first
published in 1798 in Thomas Robert
Malthus’s piece, An Essay on the
Principle of Population. Malthus
believed that the population could be
controlled in order to balance the
food supply through positive checks
and preventative checks. These
checks led to the Malthusian
catastrophe.
MALTHUSIAN CHECKS
ON POPULATION

When the increasing population rate is

greater than the food supply,
disequilibrium exists. As a result, people will
not get enough food even to survive.
People will die due to a lack of food supply.
Adversities such as epidemics, wars,
starvation, famines, and other natural
calamities will crop up which are named
positive checks by Malthus. On the
contrary, there are man-made checks
known as preventive checks.
 MALTHUSIAN CHECKS
ON POPULATION
Positive Checks
Nature has its own ways of keeping a check on the
increasing population. It brings the population level
to the level of the available food supply. The
positive checks include famines, earthquakes,
floods, epidemics, wars, etc. Nature plays up when
the population growth goes out of hand.

Preventive Checks
Preventive measures such as late marriage, self-
control, and simple living, help to balance the
population growth and food supply. These measures
not only check the population growth, but can also
prevent the catastrophic effects of the positive
checks.
 CRITICISM OF
MALTHUSIAN THEORY
OF POPULATION
The Malthusian theory was criticized based on the following
observations:
In Western Europe, the population was rising at a rapid rate. At
the same time, the food supply had also increased due to
technological developments.
Many times, food production has increased more than the
population. For eg., 2% of the total population is working in the
agricultural sector in the US. Still, the total GDP is more than 14
trillion dollars.
Malthus’s theory stated that one of the reasons for the limited
food supply is the non-availability of land. However, the
amount of food supply in various countries has increased due
to increased globalization.
 PRINCIPLES OF
POPULATION ECOLOGY

BY: LORAÑA, MARIELLE JADE K.

Population ecology studies how and why populations
of organisms grow, shrink, and interact with their
environment. These principles help predict how
populations respond to environmental changes,
conservation efforts, and ecosystem management.
 1. POPULATION SIZE
AND DENSITY
Population Size: The total number
of individuals in a population.
Density: The number of individuals
per unit area or volume. Density
affects resource use, reproduction,
and social interactions.
 2. Population Distribution
Describes the spatial arrangement of
individuals within an area. Common
distribution patterns include:
Clumped: Individuals are grouped in
patches, often due to resource
availability.
Uniform: Evenly spaced individuals, often
due to territoriality or competition.
Random: No predictable pattern, often
seen where environmental conditions
and resources are consistent.
3. POPULATION GROWTH MODELS
Exponential Growth: Occurs when
resources are abundant, leading to
rapid population increase.
Logistic Growth: Considers
carrying capacity, the maximum
population size an environment can
support. Growth slows as resources
become limited, forming an S-
shaped curve.
4. Carrying Capacity (K)
The maximum population size that an
environment can sustain indefinitely. It
depends on resources like food, water, and
shelter. When population size approaches
K, growth rates decrease, stabilizing the
population.
5. LIMITING FACTORS
Factors that restrict population
growth and can be density-dependent
(e.g., competition, predation, disease)
or density-independent (e.g., weather,
natural disasters).
6. Life History Strategies
r-selected species: Produce many
offspring, often with little parental care.
Common in unpredictable environments.
K-selected species: Have fewer offspring
with higher parental investment, adapted
to stable environments near carrying
capacity.
7. POPULATION DYNAMICS
Populations fluctuate in response to
environmental changes, predator-prey
interactions, and interspecific
competition.
Population Cycles: Regular fluctuations
in population size due to intrinsic and
extrinsic factors (e.g., predator-prey
relationships).
 8. Metapopulations
Consist of multiple, interconnected
populations. Movement among patches
allows for recolonization of empty
habitats, helping prevent local
extinctions.
 9. Demographic Processes
Birth, death, immigration, and
emigration rates shape population
structure and growth. Age structure
diagrams show the proportion of
individuals in different age
categories, affecting future growth.
by: Isidro, Jhuvan
THANK YOU!!
BY: GROUP 6