1. family and parenting
2. children

HUMAN POPULATION AND THE ENVIRONMENT
HOW TO USE THIS SYLLABUS
QUOTES
Students: The essay can include information gathered from many sources including classroom
teachers, lectures by guest speakers, libraries, parents, from the web site, or this syllabus.
In our judgment, humanity’s ability to
deal successfully with its social, economic,
and environmental problems will require the
achievement of zero population growth
within the lifetime of our children.
The introduction of this syllabus gives a summary
of the overall problems we face and why we must
learn about them and act. Important numbers, percentages, and examples of problems are in the
syllabus.
Population Summit of the
World’s Scientific Academies
Unlike plagues of the dark ages or contemporary diseases we do not yet understand,
the modern plague of overpopulation is
soluble by means we have discovered and
with resources we possess. What is lacking
is not sufficient knowledge of the solution
but universal consciousness of the gravity
of the problem and education of the billions
who are its victims.
It is especially important to read the entire story
about the Evolution of Family Size from our
beginnings hundreds of thousands of years ago to
today to have a clear sense of what is happening.
Teachers: The Teacher Information section is
for teachers (and students) to learn more about
some of the more important events. Teachers can
use this section for added information to prepare
population/environmental instruction for classrooms. Also included in this section are two
interactive and instructional games for class
participation.
Martin Luther King
Facts do not cease to exist because they
are ignored.
Aldous Huxley
Special Features:
We shall not cease from exploration, and the
end of all our exploring will be to
arrive where we started and know the place
for the first time.
• The small number after a word6 refers to the
publication from which the information was taken
and is found in the reference section.
• Included in the syllabus are drawings of some
of the threatened or endangered species of California, such as below.
T. S. Eliot
No species has ever been able to multiply
without limit. There are two biological
checks upon a rapid increase in number—a
high mortality and a low fertility. Unlike
other biological organisms, man can choose
which of these checks shall be applied, but
one of them it must be.
Harold F. Dorn. 196277
Mission Blue Butterfly
Icaricia icarioides missionensis
1
INTRODUCTION
What Does Population Crisis Mean?
The Population Crisis means: for the first time
in human history the human species has arrived at
a crossroads of survival of a livable life over the
entire world.
Santa Cruz Long-toed Salamander
Ambystoma macrodactylum croceum
One path of the crossroads leads to continued
depletion of resources, pollution, and reduction
of the ability to meet basic human needs. The other
path leads to an improved new way of life where
population sizes are in balance with the supply of
nourishment and protection.
However, we have reached a global “crunch.”
The crunch occurs when the population is increasing rapidly, and, at the same time, our basic
natural resources for survival are declining. Many
renewable resources are used faster than they can
restore themselves.1,2
Environmental protection includes maintenance
of clean water, an unpolluted atmosphere to
protect the ozone layer, and stable air temperature limits.
Technology will help us adjust to a more stable
population and lifestyles which hopefully do not
destroy our resource needs. We have always been
and will continue to be part of nature.
Since the Agricultural Revolution, we have taken
for granted that the vast resources of the earth will
never run out. They are running out! Many people
find it difficult to accept the fact that we must now:
Your awareness of these problems will help to
establish reasonable hopes for the future.
1. Stop the population explosion.
Why Hope for the Future?
2. Protect the environment (especially our lifesupport ecosystems and species).
Hope encourages us to believe that what is wanted
will happen if we work hard toward our goals.
3. Realize the importance of women having the
ability to decide whether to have children,
adopt children, or remain child free.
Today, hope is needed in young people. It is vital
for this generation to join others on earth who are
trying to stop the destruction of our life-support
ecosystems and resources. Education will be essential for yourselves and others to voluntarily
lower population numbers to a healthy sustainable level.
4. Develop technology for new energy sources
and increase the food supply.
Technology has saved us many times. Parts of the
world have seemingly impossible problems of
starvation, plagues, and refugee migration. Human inventions and intelligence saved many
people from the disaster leading to increased
population growth and further exploitation of
earth’s resources.
2
TABLE OF CONTENTS
I.
Population Numbers —Where do they come from and what do they mean? Global
and local population figures are given showing how different rates are calculated and used
by demographers. __________________________________________________________ 4
II.
Overpopulation and Carrying Capacity. Human carrying capacity is discussed to
demonstrate why population experts, sociologists, and ecologists are concerned about the
population explosion. ________________________________________________________ 9
III.
Evolution of Family Size
A. Nomadic Hunter-Gatherer and Tribal Period (200,000–10,000 years ago). Over
time humans have controlled their family size and could not severely alter the
environment because they did not have the technology or numbers to do so. Increasing
population forced migration of people to eventually occupy nearly all the habitable land
on Earth. _________________________________________________________________ 13
B. Agricultural Revolution (10,000 years ago–1750). People in certain parts of the
world learned to protect themselves from harsh environmental conditions, plow land and
grow more food, tame animals, develop cities, and create what is called civilization. These
discoveries enabled us to change the environment in a way no other animal could do. ____ 15
C. The Industrial Revolution (1750–1960) brought about global agriculture,
technology for practically everything we do, and the population explosion. This led us
on a self-defeating path of rapid growth and technological abuse of the world. __________ 20
D. The Environmental Revolution began in the 1960s. By this time, resource overuse,
world-wide overpopulation, and damaging technologies were making demands on the
environment which could not be met. __________________________________________ 25
IV.
What Needs to be Done? Many people today realize there are serious global population
and environmental problems. There is an expanding worldwide awareness and hope that
these problems can be solved. ________________________________________________ 31
V.
Teacher Information A. Characteristics of Ecosystems, B. Culture and Population
Die-offs, C. Survival Strategies, D. Severe Environmental Changes, E. Population
Data of the World, F. Activities for Students ___________________________________ 33
VI.
Glossary _________________________________________________________________ 61
VII.
References _______________________________________________________________ 65
VIII. Additional Information: A. Suggested Readings, B. Population Data, C. Source of
ZPG Teacher-Student Activities, D. CREEC-Library, E. Internet Web Sites ________ 69
IX.
Quotes __________________________________________________________________ 70
X.
Selected Index ____________________________________________________________ 72
XI.
About the Contributors ____________________________________________________ 75
3
I. POPULATION NUMBERS
TABLE 1.
WHAT’S HAPPENING TO WORLD
POPULATION IN YOUR LIFETIME?
Population numbers are important in how they
relate to human problems.
If you
were
born in:
Y6B — The Sixth Billion Year
1904
1909
1914
1919
1924
1929
1934
1939
1944
1949
1954
1959
1964
1969
1974
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
United Nations computers have targeted October
12, 1999, as the official day on which the world’s
population reaches 6 billion people.
This number may not sound very exciting to young
people who have lived their lives with at least four
billion others on Earth. But it is frightening to
people in their 70s or older. They are reminded
that the world’s population has tripled in their lifetime, from two billion worldwide in the 1920s to
six billion today. If you want to know how many
people were on Earth when you and your parents
were born, see Table 1. Note, the world’s population has quadrupled in the 20th century. It has never
done that before, and will never do it again in any
century.
Millions of people worldwide now know that
population increase must be stopped and that we
must go through a long period of voluntary reduction of the world’s population. Later sections of
the syllabus will note some of the most critical
problems.
Explosion of the Population Bomb
Dr. Paul Ehrlich, biologist and ecologist at Stanford University, is best known for his warnings
about the effects of population growth and the need
The population
of the
world was:
Since then
it has
grown by:
Before you die
it is likely
to grow by
an additional:
1.67 billion
1.73 billion
1.79 billion
1.87 billion
1.94 billion
2.05 billion
2.16 billion
2.27 billion
2.38 billion
2.54 billion
2.70 billion
3.00 billion
3.27 billion
3.64 billion
4.00 billion
4.39 billion
4.47 billion
4.54 billion
4.64 billion
4.69 billion
4.77 billion
4.86 billion
4.95 billion
5.04 billion
5.13 billion
5.22 billion
5.31 billion
5.40 billion
5.49 billion
5.58 billion
5.67 billion
5.70 billion
5.77 billion
5.84 billion
5.93 billion
6.00 billion
6.07 billion
4.40
4.34
4.28
4.20
4.13
4.02
3.91
3.80
3.69
3.53
3.37
3.10
2.84
2.44
2.07
1.69
1.61
1.53
1.45
1.37
1.30
1.21
1.12
1.03
0.94
0.85
0.76
0.67
0.59
0.49
0.40
0.37
0.30
0.23
0.14
0.07
0.00
0.49
0.59
0.68
0.97
1.25
1.58
1.90
2.24
2.58
2.93
3.28
3.57
3.86
4.08
4.30
4.51
4.55
4.60
4.64
4.68
4.72
4.75
4.78
4.82
4.85
4.88
4.91
4.94
4.97
5.00
5.03
5.30
5.53
5.76
5.87
6.00
6.13
Having
reached
a total of:
6.16
6.26
6.35
6.64
6.92
7.25
7.57
7.91
8.25
8.60
8.95
9.23
9.52
9.75
9.97
10.18
10.22
10.26
10.30
10.34
10.39
10.42
10.45
10.48
10.51
10.55
10.58
10.61
10.64
10.67
10.70
11.00
11.30
11.60
11.80
12.00
12.20
to slow it. There were 12 years of dramatic increase in population called the post-World War II
“baby boom” (Figure 1 next page). In 1968
Ehrlich wrote The Population Bomb.2 Many
people listened to Paul Ehrlich and other ecologists, and environmental and population groups
organized to educate the public.
San Joaquin Kit Fox
Vulpes macrotis mutica
In 1990, Paul Ehrlich with his wife Anne3 wrote
another book titled The Population Explosion.
What Dr. Ehrlich called a “bomb” in 1968 had
now become an “explosion” 22 years later. Obviously, things had gotten worse instead of better.
4
The “explosion“ was an extremely rapid speeding
up of what had been for 200,000 years of
our evolution an almost stable, very slow
growing population. Population increase speeded
up about 12,000 years ago at the beginning of the
Agricultural Revolution.4 It was in the last 200
years during the Industrial Revolution that population increased very rapidly. It continues to do so
(Figure 2, page 6).
world. These worldwide figures are available to
other countries, to the United Nations, and to private groups. Population information is gathered
in the United States by government agencies such
as the US Census Bureau or private groups such
as the Population Reference Bureau.5 Most of the
figures in this syllabus are from the latter group.
Fortunately, there is a worldwide awakening to
the problems. There are already 14 countries in
the world where the population is now declining
(Teacher Information page 52). There have been
many times in history when the population of
countries has declined because of famines,
plagues, wars, etc. (Teacher Information page
36). The people in the countries where the population is declining are reducing their growth rate
voluntarily and with purpose.
Family size (fertility rate) is the average number
of children a woman will have in her child bearing years. Family size for a nation is the average
size of all the families. Women without children
are included in the average. Abortions and stillbirths are not included.
Family Size
Family size has been dropping for several years
in the world. However, in the poorer or developing countries, it is still very high (Teacher Information pages 52–53) with the highest in Niger at
7.5 children average per family. Italy and Spain
are two of the eleven countries in the world with
an average of 1.2 or less children per family.
Where Do the Numbers Come From?
Population numbers are collected from farm communities, towns, and cities in each country of the
BIRTH RATE
NUMBER PER THOUSAND POPULATION
30 (Not recorded)
28 Cause of Decline:
Unemployment and
26 Economic Depression
24 equals smaller families*
j
p
22
20
1918 Flu
18
Depression
16
Cause of increase:
Great hopes for the
future with feelings
of euphoria = larger
families
n
Causes of Decline:
• More contraceptives
now available
• Uncertainty of future
• Environmentalism
• Smaller families for
economic reasons
14
i
12
DEATH RATE
10
– The Spanish Flu –
About 650,000 died in the U.S.,
8 and 22 million globally (see page 39)
6 Nearly all the deaths were in 1918.
4
2
YEAR
0
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Figure 1. United States Birth and Death Rates, 1900–1999
Data Plotted at two year intervals. Data from U.S. Vital Statistics: Vol. 1 – Natality, Vol. 2 – Mortality; and
Population Reference Bureau, 1994–1999. * This occurs in richer countries. In very poor countries when
conditions get worse, people often have larger families for old-age security.
5
It took about 200,000 years for our
species to reach the first billion. From
then on, due to exponential growth, the
years between billions have become
less and less. The world’s population is
doubling every 49 years.
Years
Year
Between
Billion
Billions
People Reached
First
Second
Third
Fourth
Fifth
Sixth
1800
1930
1960
1975
1986
1999
This is called demographic momentum. Momentum keeps an object moving or continuing such
as a car after the engine is turned off. With
population numbers, it will continue to increase
as long as the birth rate is higher than the death
rate. Remember, this can happen even if the
average family size is well below 2.1 per family.
BILLIONS OF
PEOPLE
6
5
4
200,000
130
30
15
11
13
There are 39 countries where the average family
size is less than two but they are still increasing in
numbers. These will reach zpg or npg within a
few years if family size stays the same or
declines.
3
2
Countries with either zpg or npg and those near
zpg are in Europe, United States, Canada, Australia, New Zealand, and Cuba.
1
YEAR
1500
1600
1700
1800
1900
Growth Rate
2000
Figure 2. Global Population Increase,
1500 – 2000
Growth rate is the natural increase from births
in a country. It does not include immigration.
Source: Zero Population Growth
Growth rate is computed by subtracting the number of deaths per 1,000 people (death rate) in the
country from the number of births per 1,000 people
(birth rate) written as a percentage.
The rich or developed countries have a family size
below or near the average of 2.1 children per family. An average of around two children per family
is all that is needed to keep the population at
around the same numbers. In other words, two
children replace their parents in the population.
When a population continues for several generations at an average of 2.1 children or less, the
population will not increase when birth rates are
about equal to death rates. This is called zero
population growth (zpg).
For example, in Finland the number of births per
1,000 population is 12 and the number of deaths
per 1,000 is 11. Thus, 12–11 = 1 and the natural
increase or growth rate is 0.1 percent. The average family size is only 1.7 children, well below
the replacement level, but the population is still
increasing.
If the death rate becomes higher than the birth rate,
the population decreases. This is called negative
population growth (npg).
Peregrine Falcon
Falco peregrinus
Demographic Momentum
There can still be a population increase even if
the family size is below 2.1. This can happen when
the population has a much larger number of young
women having children compared to women,
usually over 45 years of age, who cannot have
children.
6
population of six billion would be six times greater
than at one billion people. The larger the population, the faster the growth. What made matters
worse is that throughout the population explosion,
global population growth rates increased.6
Singapore as well has an average family size of
1.7, but the birth rate is much higher because it
has a “young” population. The number of births
per 1,000 is 15 and the number of deaths per 1,000
is 5. Thus, 15 – 5 = 10 yielding a growth rate of
1.0 percent.
Exponential increase along with greatly increased fertility rates contributed to most of
the population explosion. Decrease in mortality
was also a factor, but it was not as important as
the increase in fertility rates.
Exponential Population Increase
It appears so far that population growth is simply
determined by the number of births and deaths
and the number of young and old people in a population. Unfortunately, it is not that simple. There
is another thing happening that is very important
now that the human population is in the billions:
exponential growth.2
Doubling Time
The estimated years in which a population will
double in numbers is computed by dividing the
number 70 by the growth rate percentage. The
doubling time of the population in Singapore is
69 years, whereas in Finland it is 459 years. There
are more young people growing into the reproductive age in Singapore than in Finland. This
difference will last many years.
Suppose you have a bank account and collect interest. If you leave the interest in the account, the
amount you earn each year increases because the
total amount in the account now includes the original amount plus the interest. The amount you will
earn will increase each year even if the interest
remains the same.
The dominance of young people in the world
today is seen in the “pyramid” of numbers of less
developed and more developed countries (Figure
3). Each bar consists of males on the left side and
females on the right side. Each bar represents a
5–year span of age starting with 0–4 years and
ending with 75–79 and 80+ years. The millions
of males and females is represented on the horizontal. The age-group is on the vertical.
The same thing happens in human populations.
Because more children are added each year than
people who die, the human population will continue to increase even with the same growth rate.
The size of the population makes a big difference.
With the same growth rate, the increase in the
Age-group
Critical Cohort
Sources: United Nations Population Division, 1998,
and Population Reference Bureau5
Figure 3. Pyramid of Age-Groups
7
Population Explosion.
TABLE 2. WORLD AND UNITED STATES
POPULATION, 1999
Mortality, especially for children, has always been
a major concern and fear of humans. In ancient
hunter-gatherers the average age was around 18
and an old person was 40 years of age indicating
high mortality throughout life.
WORLD UNITED STATES
1999 Population 5,982,000,000
272,500,000
(Estimated, mid-June)
Modern medicine has resulted in many more
people living longer. Some people have felt that
the decrease in mortality caused the population
explosion. Mortality was a factor, but in a minor
way, especially in the last 100 years when most of
the increase occurred.7
Note the birth and death rate curves for the United
States from 1906 to today (Figure 1, page 5).
Except for the sharp increase in mortality during
the 1918-20 Spanish Flu, mortality decrease had
little to do with the population explosion. The
Spanish Flu killed over 650,000 people in the
United States and over 22 million people worldwide (Teacher Information page 39 for more
information).
BIRTHS
year
month
week
day
hour
minute
second
137,586,000
11,466,000
2,866,000
409,000
17,062
284
4.7
4,088,000
341,000
85,250
12,179
507
8
-
DEATHS
year
month
week
day
hour
minute
second
53,835,000
4,486,000
1,122,000
160,223
6,676
111
1.9
2,453.000
204,400
51,100
7,300
304
5
-
NATURAL INCREASE
year
83,751,000
month
6,980,000
week
1,744,000
day
248,777
hour
10,386
minute
173
second
2.8
1,635,000*
136,600
34,150
4,880
203
3
-
Data from Population Reference Bureau.
*Does not include migration into U.S.
Population growth in the world and in the United
States by year, month, day, hour, minute, and second shows how much further family size reduction must occur in the developing countries (Table
2). The United States figures do not include immigration numbers. Today about 40 percent of the
population increase per year in the United States
is from immigrants. Thus, the total increase in
population per year in the US is about 2.8 million
people.10
12
Billions
10
High
8
Medium
Low
6
4
What About Future Population Numbers?
2
Recent estimates of future population numbers
indicate it will not be as large as some of the past
predictions indicated. There has been a surprising decline in family size in many developing
countries which, if it continues, will ease fears of
the future for the planet.
0
1950
1970
1990
2010
2030
2050
Figure 4. World Population Projections,
1950–2050
Source: Brown. Gardner, and Hawell43
many reasons at 6 billion today, it is obvious we
will have to change our lifestyles and values to
survive. We must quickly speed up family
planning education and clinics around the world.
Future population estimates at three levels of
growth rates show that the medium estimated
world’s population in 2050 will be 8 billion
(Figure 4). Considering we are overpopulated for
8
II. OVERPOPULATION AND
CARRYING CAPACITY
they further degraded the environment, removing
brush for firewood, and ended up with a grassland island with a few areas of brush. The
carrying capacity continued to be lowered and
the population continued to drop, with increased
mortality. Continuing to deplete resources after a
population exceeds its carrying capacity is called
“overshoot.”8
What happened to the people who occupied
Easter Island?
When about 20–30 Polynesians from the
Marquesas Islands landed on rafts around 400–
500 C.E. (Common Era = A.D.), the island had a
lush forest with food and many kinds of trees. They
brought chickens and some food plants, but most
would not produce in the cool climate.
Physical and environmental limiting factors were
made worse due to their social behaviors and religion which they would not change in spite of worsening conditions (see Teacher Information page
37 for more details of this unfortunate collapse of
the highly organized society and what happened
to six other societies that extended their carrying
capacity).
Apparently with no fear of starving in the future,
the population built up rapidly to 7,000–12,000
people by 1550. About that time the forest had
been removed, water retention of the soil became
poor, and soil erosion took place. When all the
trees were gone, they could no longer build boats
to catch fish and dolphins which were their main
sources of food. They started to starve, and wars
and cannibalism prevailed until they were discovered in 1722. There were 2,000 Easter Islanders
remaining. In 1870, only 110 were alive (Teacher
Information page 37).
What is Overpopulation?
Simply stated, overpopulation occurs when a
population in a given area exceeds the carrying capacity of the land.
The following definition tells us that humans have
already reached a state of overpopulation in the
world: 3
Several limiting factors were operating at once
causing this rapid decrease. The land could no
longer carry that many people because its
capacity to keep them alive and healthy was
lowered. Once the land became overpopulated,
If the long-term carrying capacity of an area
is clearly being depleted by its current human
occupants, that area is overpopulated. By this
standard, the entire planet and virtually every
nation is already vastly overpopulated.
How About Other Species?
What are the definitions of “overpopulation” and
“carrying capacity” for other species?
In land management, or in places where humans
may have little or no effect, it is not difficult to
determine if a population is healthy. If the population of a species is declining or in a continual
state of undernutrition and disease, the population
numbers are above the ability of the environment
to carry or support them at that level. It is thus
overpopulated.
Drawing from William R. Catton Jr., 19948
9
If a non-human population is increasing, it means
that the population is below the capacity of the
land to support it. It is not overpopulated.
Physical Limits
Like all living things, humans are still under the
control of the basic environmental physical
limits. When these limits are reached and the
population begins to decrease or people are in
constant hunger and misery, physical environmental overpopulation has taken place.
Wildlife conservationists as well as land and resource managers (farmers, livestock grazers, foresters, fishermen) consider that if a population
remains within certain numbers over many years
and the environment is not being degraded, the
population is at its carrying capacity.
The results of physical overpopulation on humans
can be the same as in all non-human species when
they exceed their carrying capacity. The outcome
may be starvation, disease, migration, and
increased predation (for humans this is war).
Our species lived under these physical limiting
conditions for the first 200,000 years of its evolution. That is why our population remained at near
zero population growth until the Agricultural
Revolution.
Physical Environmental Limits
The environmental physical limits that have
controlled all plant and animal species over the
billions of years since life appeared on the planet
are:
water
temperature
food
clean air and water
adequate safe space
species habitat requirements
Ecological Limits
Carrying Capacity Expressed as a Number
A new form of environmental human overpopulation occurred with the development of agriculture and the destructive technology applied to
natural resources. Locally, the effects can appear
in a very short term, but globally some of them
may take hundreds of years before they are
noticed. Following is a list of environmental factors which can lower the carrying capacity of that
environment if they are severe for any species.
A general definition of environmental carrying
capacity is the number of a species which can
exist for a long period of time (ecologists say
indefinitely) in an area without degrading the
habitat.
When the environment is degraded by short or long
term changes in the natural physical limits or by
human changes of the habitat, the carrying capacity (number which can live there) will be lowered.
What is Human Carrying Capacity?
For humans, carrying capacity refers to the
number who can be supported without degrading the physical, ecological, cultural,
and social environments. Carrying capacity
relates to the desired quality of life.7
Note in this quote there are actually three types of
environmental limits for humans: physical, ecological, and social. Culture is considered to be
part of the social environment.
©Scott Miller
10
SO WHAT’S ANOTHER 80 MILLION—MORE OR LESS?
ACID
RAIN
MORE
GLOBAL
WARNING
MORE
STRESS
MORE
SICKNESS
MORE
TOXIC
WASTES
MORE POWER
PLANTS AND
FACTORIES
MORE
TRAFFIC
MORE AIR
AND WATER
POLLUTION
LESS
SCENIC
BEAUTY
MORE
URBAN
SPRAWL
LESS
WILDLIFE
MORE
GARBAGE
MORE OIL
SPILLS
MORE
CROWDED
CITIES
MORE
UNEMPLOYMENT
MORE
CRIME
MORE
POVERTY
THE WORLD’S
POPULATION
IS GROWING BY
OVER 80 MILLION
PEOPLE
A YEAR
LESS
LOW COST
HOUSING
MORE
TAXES
MORE
HOMELESSNESS
MORE
OVERGRAZING
MORE
GLOBAL
WARNING
MORE
POLITICAL
UNREST
MORE HUNGER
AND SUFFERING
Figure 5. Effects of Increasing Population
loss of topsoil
freshwater pollution
air pollution
desertification
ocean pollution
ozone layer loss
deforestation
dropping water tables
rising sea levels
species loss
MORE
DEFORESTATION
LESS ARABLE
LAND
PER PERSON
LESS FRESH
WATER
PER PERSON
Various combinations can quickly cause severe
ecosystem damage (Figure 5):
MORE
ENERGY
DEMANDS
MORE
DESERTS
MORE
INTERNATIONAL
CONFLICTS
Source: Zero Population Growth
All are interacting ecological problems, and the
health of the life-support ecosystems vital to our
survival may deteriorate (see Teacher Information
page 34 for discussion on ecosystems.)
global warming
less firewood
siltation of rivers
exhaustion of soil
overgrazing
shrinking wetlands
bioinvasions
acid rain
loss of cropland
toxic wastes
Several years ago ecologists9,10 suggested that the
carrying capacity of the earth is around two
billion people. They believed that if the human
population a hundred years from now is not down
to about 2 billion people, permanent damage will
be done to our life-support ecosystems. This is
one of the reasons why we have a population
crisis today.
Many of these are caused by the beginning of
another. For instance:
A recent statement on overpopulation reminds us
of the importance of thinking about children of
today and those in the future who will be affected
by degradation of the environment. Human overpopulation has:6
DEFORESTATION can cause loss of topsoil,
which degrades the wilderness, pollutes fresh
water flowing off the area which causes silting
of rivers that destroys salmon spawning beds. This
leads to other species loss and depletes commercial and recreational fisheries.
…not only exceeded its current carrying
capacity, but is actually reducing future carrying capacity…our descendants will have
11
© Max Rain
The first human leaving the safety of the forest
When humans could walk upright they were no longer trapped to living in the forest. They could
now venture into the grasslands where food was plentiful—but there were new dangers.
fewer of the essential requirements of lifesupport than we have today.
Some important human social-cultural needs and
values are:6
quality health
safe streets
to have a job
no wars, less crime
no excessive traffic
gender and racial tolerance
no overcrowded places
privacy and shelter
protection of nature and wildlife
democratic decisions
safe and good recreation
a good education
freedom of movement
adequate and safe food
women’s, men’s, and children’s rights
scenic beauty and open space
The reason why so many environmental problems
exist is that for hundreds of years humans have
taken for granted that the vast resource base of
the earth will never run out. Or, if resources do
run out, some believe we may be able to find some
technological substitutes for them. However, most
technological “answers” are merely temporary as
long as population numbers increase.
Human Social Limits
When resources are depleted, people in a culture
or nation can no longer live the life they have become accustomed to or attain the life they desire.
This is called “quality of life” carrying capacity.
Overpopulation is Becoming More of a
Problem.
Quality of life is less when people overwhelm in
numbers the good things available. Social desires
and needs are denied when we seriously damage
the habitat or because of overuse of resources
due to population numbers. Uneven distribution
of resources and money is also a serious problem
in all societies. Thus, numbers of people combined
with habitat damage, and overuse and uneven distribution of resources are the main contributors
to social overpopulation in all societies.
In the past, these needs and desires were not satisfied because of economic and political problems,
and population was less of a problem. However,
overpopulation is now often the cause for the inability of people to achieve desired quality of life.
Overpopulation is now becoming a basic cause of
economic and political stress.11
12
III. EVOLUTION OF FAMILY SIZE
They also understood fully how they were affected
by the physical limits of nature. If they had more
members of the tribe than they could feed during
bad times, it would endanger the entire group.
Food was scarce and humans had to keep moving
as food sources seasonally and locally became
available.
A. NOMADIC AND TRIBAL PERIOD,
200,000 TO 10,000 YEARS AGO
The very first “human” types of apes appeared
about 3.5 million years ago in the center of Africa
from Ethiopia into South Africa. Fossil records
do not have our species, Homo sapiens, before
200,000 years ago.12
Animals Evolved With Inherited Traits to Limit
Population Size
Reproductive control occurs primarily during
times of population stress such as droughts, floods,
prolonged extreme temperatures, and when habitat is seriously degraded. Here are three examples
(examples of the sea otter and aphid are given in
Teacher Information page 40):
How did humans control their family size when
they were nomads and hunter-gatherers?
Until the Agricultural Revolution, humans had the
same environmental physical limits as other animals, and behaved as other animals in limiting
their reproduction when times were not good for
survival of the offspring.
a. When food, primarily deer, becomes scarce for
mountain lions, the larger males kill younger and
weaker lions. This lowers the population and the
surviving healthiest and most experienced members will live to reproduce when conditions are
better.14
Life was hard for hunter-gatherers and mortality
was high. They were nomadic roaming people who
lived from day to day on the food they gathered
or killed.
b. A different behavior keeps lemmings (a kind of
mouse) from overpopulating and destroying their
habitat. In the fall, there is often a glut of these
animals in the high mountains of Scandinavia.
When crowded, they head downhill with some
left behind to continue the population next spring.
It was long believed they did this because they
were starving. Later studies showed on the contrary, that they did this before the habitat could
be damaged. Lemmings exhibit crowd-stress behavior and many of them will leave the crowded
area heading downhill. They may end up being
eaten by predators or drowning, but if not, they
keep moving until they die when they cannot find
food.The migrants do not set up new colonies.15,16
They lived in small bands of probably up to about
20–50.11 Present nomadic family units in Africa
number about 50–60 people. The men hunted and
fought off occasional attacks by large animals.
They may also have had to protect their groups
from possible hostile bands of other hunter-gatherers. Women kept their family size low because
they could not carry all the supplies, gather food,
nurse a baby, and possibly tend to older children
at the same time.13
c. A rabbit will breed only when the female is in
her estrous period (see page 62). When food becomes scarce, females lacking sufficient nutrition
stop having estrous periods. They do not start
breeding again until sufficient food restores their
health and estrous periods restart.
San Francisco Garter Snake
Thamnophis sirtalis tetrataenia
13
Hunter-gatherers
a tribe of nomads, the !Kung bushmen of South
Africa, have a child only about every four or five
years.
Unknown to them, hunter-gatherers had a built-in
genetic “family planning” method. Mothers nursed
their children for 4.5 to 5 years. There was not
enough soft food, and meat was hard to digest by
the very young. Babies nursed on “demand”
which meant whenever they wanted to be fed, the
mother would nurse. Nursing occurred from
2–4 times per hour and for 2 to 3 minutes each
nursing.
“Prolactin” birth control did not evolve starting
with humans. It started millions of years before.
The chimpanzee, our closest living ancestral relative, also has 28-day menstrual periods like humans and does not ovulate when nursing.18
In modern times, nursing is not a birth control
method in rich countries. Mothers today who have
a good diet and have stored surplus energy in the
body rarely produce enough prolactin to stop ovulation. Nursing mothers today limit how long and
how often they nurse.
When a human mother nurses, a hormone is
secreted in the pituitary gland of the brain called
prolactin (in Latin, pro means for and lactin
means milk) which does two things. It starts the
production and flow of milk, and it stops release
of eggs to be fertilized.17
A hunter-gatherer woman could not give birth to
more than four or five children in her lifetime when
children are spaced five years apart. (There would
also be high child mortality, bringing the average
down further). However, with four maximum children in their lifetime, there could be increases in
the population leading to mass starvation during
times of food shortage.
Nomadic hunter-gatherers for hundreds of thousand of years were barely hanging on to life, and
every bit of food had to be efficiently used or they
would die. There was barely enough milk produced by a mother to feed one baby, so the
survival of the individuals depended on inherited
and learned behavior which would ensure that the
one child would survive. For example, women in
Through their intelligence, hunter-gatherers
developed ways of controlling their population.
Every culture had ways of doing this when weather
conditions caused famines or when hunting and
fishing was failing from changes in migrations of
animals. Other ways for the hunter-gatherer to
survive included to migrate, and to steal food and
goods from neighbors or other tribes.
Migration was most important as long as they
could do so. If a wandering tribe or family group
ran out of food, all they needed to do was expand
into an area with no people and plenty of food. In
this way, increasing numbers of one of our ancestors, Homo erectus, moved out of Africa into the
warmer areas of Asia 2 million years ago; and into
Europe about one million years ago.11,12,83
©Scott Miller
“Got everything, Hon?”
As hunter-gatherers, our ancestors left Africa about 2
million years ago to occupy most of Europe and Asia.
When they moved to a new area, the women carried the
belongings. The mother could not take care of and feed
more than one small child—their children were spaced
4–5 years apart.
After most of the food rich land was occupied and
migration was no longer possible, tribes started
setting up boundaries to protect enough resources
14
the largest grains or fruits were saved to be planted
next season to yield better crops. The most docile
animals and those that produced more milk or
wool, or had other desirable qualities were selected
for breeding.
to ensure survival of the group. Punishment for
crossing into another tribe’s boundaries without
permission resulted in being made a slave, killed,
or sent back to their own tribe.19
The population during this period was considered
to be at zero population growth. There was high
mortality and low fertility, and the people apparently had a sense of ecological restraint
(Figure 6, page 19).
Domestication of animals, cultivation, and of seed
and fruit improvement of plants were some of
the most important environmental adjustments for
survival ever made by humans:20
Domestication is probably the single greatest technical achievement in the human
record, more important than the internal
combustion engine or nuclear energy. It was,
from the beginning and long before those
other triumphs, a remarkable way to capture and control energy.
B. THE AGRICULTURAL
REVOLUTION, 10,000 YEARS AGO
TO 1750
The first domesticated animal was the gray wolf;
the origin of all the present dog varieties.13, 84
The reindeer was a close second, and about 15,000
years ago, food plants and animal species were
beginning to be planted and tamed.
Now that grains and hay were available, animals
could be kept close by or in captivity. The more
docile ones were domesticated. Domesticated animals now supplied food and hides, and were used
for riding and pack transport, for hauling carts,
and plowing.
By 12–8,000 years ago this was taking place on a
larger scale at several places in the world. These
places were along the Nile River in Egypt, the
Mesopotamia area of the Middle East along the
Tigris and Euphrates Rivers, the Indus Valley of
India, and the Yellow River Basin in China. About
four to five thousand years ago localized agriculture evolved independently in Central America and
in the Inca area of South America.11
Wheat, oats, barley and rye came from the Mediterranean area, and rice and soy beans from Asia.
Corn, beans, squash, pumpkins, and tomatoes
came from Central America. The Inca Indians in
the Andes Mountains of South America developed
several varieties of potatoes.
The domestication process was simple, but it took
several millions of years for our ancestors to
arrive at that point in history. Seeds of plants with
Goats, and sheep came from Europe and Northern Africa. The common “Western” beef and milk
©Scott Miller
“Get out of here, you pest:” (How the wolf was tamed and became a dog.)
At first, tamed wolves and humans worked together for each to get more to eat.
After the wolf was domesticated, humans and dogs became good friends.
15
cattle varieties came from Europe; the domesticated pig came from Asia. All chickens were bred
from the red jungle fowl of Bangladesh. The llama
of the Andes Mountains was used as a pack animal but not to haul carts because the wheel had
not been invented in the Western Hemisphere.
only about 170 million in the year 1 C.E. (Table
3).
We learned on page 7 that the larger the population, the faster it grows. Rapid population growth
TABLE 3
ESTIMATED POPULATION NUMBERS IN
HUMAN EVOLUTION: ONE MILLION
YEARS B.C.E. TO PRESENT
Agriculture is the science of farming, livestock
grazing, and pasturing. It remained localized for
many thousands of years. Humans began to control and change their environment, had more food,
and worked cooperatively with others. More laborers, sheep herders, farmers, soldiers, teachers,
and traders were needed. Gaining more people and
work forces was accomplished either by having
larger families, paying people to work, or capturing people from neighboring areas as slaves.
Source: Kremer, 199373
Year
Number in
- = B.C.E
Millions
-1,000,000
-300,000
-25,000
-10,000
-5,000
-4,000
-3,000
-2,000
-1,000
-500
-200
1
200
400
600
800
1000
1100
1200
1300
1400
1500
1600
1700
1750
1800
1850
1875
1900
1920
1930
1940
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
1999
2000
What happened to family size from 12,000
years ago to 1700?
Most people of the world until about 3,000 years
ago were still living in primitive ways and
controlled their family size with traditional methods along with the genetic prolactin reproductive
restraint (see page 14). However, in areas where
agriculture was becoming a way of life, more children were needed. More kinds of foods were now
available for children. Better houses could protect them from the weather. The fear of starving
and being unsafe was lessened, and the ecological restraint of the hunter-gatherer period began
to change to an attitude of ecological release.7
Using their agricultural and technological improvements and increasing family size to have
more workers gave people greater control over
their environment. In the fertile crescent lands of
Mesopotamia the religious command to “be fruitful and multiply” arose. But eventually these new
innovations and increase in population led to the
destruction of the Mesopotamian culture as well
as others (Teacher Information page 36).
But, why was there not a population explosion
then as we have now?
The world’s population was still very small. About
5 million lived on Earth 10,000 years ago, and
16
(125 thousand)
1
3.3
4
5
7
14
27
50
100
150
170
190
190
200
220
265
320
360
360
350
425
545
610
720
950
1,200
1,325
1,625
1,813
2,000
2,213
2,516
2,752
3,020
3,336
3,698
4,079
4,450
4,851
5,292
5.702
6,000
6,080
Today this male-dominant attitude persists in Islamist countries where men interpret the Koran to
support their dominance over women. However,
there is a new trend by the heads of State of some
Islamic countries and Muslim religious leaders.
They remind Muslims that there is nothing in the
Koran (the Muslim holy book) which says women
cannot use contraceptives or men cannot have vasectomies, or that women are not equal to men.
This discussion on gender bias in some Islamic
cultures is presented to demonstrate a souce of
these attitudes. Gender bias occurs in all cultures,
not just Islamic societies.
California Least Tern
Stema antillarum browni
did not start taking place until about 1700 when
the population was around 600 million.
Other Fertility and Mortality Events
Also, agriculture was still very localized. Most of
the world’s people still lived in small communities, living off the land with some advances in raising food.
• Although mortality was generally eased because
of better diet and protection from the environment,
in some areas mortality increased. When people
became crowded in towns and villages, it enabled
contagious plagues to kill millions of people. The
Black Death in the mid-1300s killed 20 percent
of the world’s population—75 million people
(Teacher Information page 40).27
Pastoralism—a new way of life—10,000 years
ago to present
There were many cultures spreading throughout
Asia and into Africa based on pastoralism.
• Wars occurred in which hundreds of thousands
were killed. There were riches stored in cities,
valuable farm land cleared and plowed for cropland, and livestock herds. All these riches became
the rewards of invasion by neighbors or by armies
of great empires. Livestock was a favorite target
for theft, especially by young grooms who needed
sheep and cattle for bride price (see page 24). Livestock thefts occurred nearly worldwide, including the Navajos who were temporarily confined
to a reservation because of their raiding behavior
for livestock21 (Teacher Information page 49).
Pastoralism is the herding of sheep and goats as
well as cattle. Pastoral herders converted grass into
food and energy through domesticated animals.
These societies became common throughout
Europe, Asia and parts of Africa where sheep and
goats could be grazed and where the land was not
valuable for cropland. Spaniards introduced sheep,
goats and cattle to the Western Hemisphere in the
1500s. The Navajos using these sheep and goats
became the only true pastoral culture in the United
States.
One of the most damaging military actions and
destruction of a way of life was the invasion of
China by the pastoral Mongols in 1324. During
the Mongol 300-year occupation of China, 30 million Chinese died (Teacher Information page 41).
The way of living in pastoral societies has had a
profound effect upon the world’s fertility levels
since its beginnings at the start of the Agricultural
Revolution. Pastoral societies were warlike. They
had larger families because they had to literally
fight for grazing lands in the summer and watering and food areas in the winter. It became a patriarchal society in which women were to bear
children. They took care of the family affairs and
lacked equality with men.
• Crop failures and famines were common.
Droughts occurred regularly, and in areas long
used for irrigation the soil became salted and/or
waterlogged and lost its fertility 11 (Teacher
17
chicken, pig, and fish farms.
The framework had been laid for the Industrial
Revolution and the population explosion which
was about to take place. This included: desire to
have more children, lower mortality because of
better medical care and nutrition, and need for labor. There were also vast open areas in the Western Hemisphere with tremendous resources to be
tapped and space to be occupied by Western cultures. There was new technology which enabled
extraction and use of these resources. Finally, the
size of the population around 1700 initiated an
increase in the rate of exponential growth.6
Humpback Whale
Megaptera novaengliae
Information page 36). There is evidence of soil
erosion many thousands of years ago in Mexico
from hillside corn growing.22
• The potato was brought from South America to
a hungry Europe by the Spaniards in 1565.23 A
dramatic population increase took place in some
areas. In Ireland, the population increased from 3
million before the potato was introduced to over
8 million in 300 years. The potato was their main
food item along with mutton. Starting in 1845,
the potato blight killed practically all the potatoes.
During the ”Great Hunger” two million Irish
people died of starvation and three million migrated, mostly to the United States (Teacher Information pages 38–39).
However, bare subsistence and poverty conditions
still existed for the majority of humans on earth.
In the cities, slums of poverty were developing
and child mortality was high. Working conditions
were slave-like and many young children were
forced to work.
An impasse developed preventing further betterment for people, and the increasing population
made matters worse. Human society was reaching another breakthrough from lack of resources
due to overpopulation.4,11
Did agriculture and technology make life
easier?
Humans, like all other animals, continue to increase in numbers and expand their control over
the environment as long there is energy and space
available. In other words, when humans are below carrying capacity, the population will increase.
When the new level of carrying capacity is reached
and conditions become unpleasant, people have
fewer children. If they don’t have fewer
children, mortality increases from hunger and
diseases.
It certainly did, but not without a severe price
which was to be paid by millions of people and
the environment. Complex and beautiful cultures
flourished and then faded. The Egyptian,
Babylonian, Assyrian, Byzantine, the Greek citystates, the Roman Empire; and in the Western
Hemisphere, the Inca Empire and Maya cultures,
all came and went in their splash of glory, art and
inventions. Studies have revealed that many if not
all of these cultures abused the environment in
ways which contributed to their breakdown11
(Teacher Information page 36).
After each new release from population limits by
some human invention, such as domestication of
animals or the plow, our fertility potential quickly
reaches the new level of carrying capacity. We are
now at the next breakthrough. In the Industrial
Revolution, vast natural resources will become
available through new technology.
It was not until the Industrial Revolution and
its technology with worldwide transport of
domesticated plants and animals that most people
of the world could take advantage of intensive
farming and raising of livestock. Surplus of grains
now led to the feeding of cattle in feedlots and
18
Population today
BASIC SURVIVAL
Starting 200,000 years ago
• Fire
• Tools
• Low fertility
• High Mortality
Resources unsustainable, return to
ECOLOGICAL RESTRAINT
INDUSTRIAL REVOLUTION
Population 1 billion around 1800
• Health
• Scientific method
• Fossil fuels
• High fertility
• Low mortality
• Pollution & Resource Depletion
AGRICULTURAL REVOLUTION
Population 5 million 12,000 years ago
• Food crops
• Cities and writing
• Higher fertility
• High mortality
• Domesticated animals
5
ECOLOGICAL RELEASE
ENVIRONMENTAL REVOLUTION
Population 5 billion around 1985
NEEDS:
• End of population increase
• Women’s reproductive rights
• Renewable energy
• Reduce use of resources
• Protection of plants, animals,
and ecosystems
• Low mortality
• Low fertility
100.000
YEARS AGO
3
1
12,000
Figure 6. Human Revolutions and Population Numbers
Data compiled by Santa Cruz/Monterey Chapter, Zero Population Growth
Desert Tortoise
Gopherus agassizii
19
4
2
ECOLOGICAL RESTRAINT
200,000
6
B
I
L
L
I
O
N
S
O
F
P
E
O
P
L
E
C. THE INDUSTRIAL REVOLUTION,
1750 – 1960
which set off the population explosion and destruction of resources and habitats.
The tremendous storeroom of food, energy, animals and plants which evolved and accumulated
over the 3 billion years since life first appeared
on earth, was about to be raided, setting off the
Industrial Revolution.
What speeded up the exploitation of resources?
The development of the scientific method, the discovery of fossil fuels for energy, technological
innovations, and rapid population growth were significant. However, another human use of resources
evolved.
Throughout the Agricultural Revolution, humans
barely scratched the surface of what was there.
Creative people in the Agricultural Revolution
tapped into a few more sources of energy and food,
but there was a vast reservoir of resources still
unavailable.
In the late 1700s, humans found a new purpose
for the exploitation of the earth’s environment and
its natural resources. This new purpose was more
than just supplying mere existence, security, and
basic needs. It was the economic accumulation of
monetary wealth.
Humans soon developed ways of finding, removing, refining, and using natural resources. The
technology developed to do this was accompanied
by a LOW death rate and a HIGH birth rate
Economics became a “science,” dominating human values. Resources became “natural capital”
creating wealth and money. When invested, it became “capital” making more money. Economists
use natural capital to create economic or investment capital. Governments tax investment profits and salaries and use the money for social capital. Social capital is needed for education, streets,
fire and police departments. It is needed for
all other city, county, state, and national
services and protection.
Affluence now becomes a key factor in determining carrying capacity and impact on the environment. Paul and Anne Ehrlich3 have presented the
formula: I = PAT. This says:
Impact on the environment =
Population x Affluence x Technology.
Affluence is the amount of resources being
consumed by each person. Technology is the environmental damage done by the technology to
obtain the resources. Population is the number of
people.
©Max Rain
The United States with 4.6 percent of the world’s
population consumes 25 percent of the world’s
energy and 35 percent of the world’s resources.
Our country has one of the highest affluence rates
in the world, uses destructive technology and has
“It’s your fault!”
Affluence and poverty have been with us since the
Agricultural Revolution. Extreme unequal distribution of
resources between the rich and poor increases family size,
poverty, and depletion of resources.
20
the third largest population. Twenty European
countries use energy more efficiently than we do
in the United States.
One of these was Thomas Malthus (a minister and
intellectual) who stated that humans reproduce
faster (exponentially) than food can be grown to
feed them. Malthus did not know that technology
would temporarily increase food production to
keep even with population increase. A recent example is the Green Revolution (see page 24).
Distribution of Food and Resources
The massive accumulation of wealth in the rich
countries combined with the poverty of poor countries created serious obstacles to solution of
social and environmental problems. Uneven distribution of resources, which is a major problem
today, became severe during the colonial times
from 1700 to 1945. Many non-developed countries in the world came under the forced control
of a few European countries.
Historian Clive Ponting11 describes Malthus’
frustration:
His (Malthus) Essay on the Principle of
Population, published soon after 1798, argued that there was a permanent cycle in
history in which human numbers increased
until they were too high for the available
food supply, at which point famine and disease would reduce the population until it was
again in balance with the amount of food
that could be produced. Malthus could see
no way out of this terrible cycle. During the
nineteenth century the Malthusian view of
history was largely ignored and the idea of
progress became almost universally accepted as the natural, unspoken assumption.
Fair and equal distribution of resources is still a
major problem, and it will be for a long time. Some
sociologists claim that population is really not the
problem. It is really a matter of distribution, and
the solutions lie only in social and economic
changes (Teacher Information page 34).
Unfortunately the social and economic changes
needed to solve the present poverty and environmental problems will take several generations. If
people in developing countries are told and believe that overpopulation is not a major problem,
then they will suffer generations of starvation,
poverty, and high mortality before the social and
economic solutions may appear.
Such optimism was felt to be justified by
the huge material progress made by Europe
in the nineteenth century: its ability to feed
an ever larger population …Gradually it
(progress) came to be commonly accepted
among European intellectuals that history
was the story of a series of irreversible
changes in only one direction—continual
improvement. The eighteenth century was
marked by a wave of optimism about the
future and the inevitability of progress in
every field.
It is proven in many developing countries that family planning education will lower family size, and
that emancipation of women leads to more secure
families. Lowered family size is essential to
bring about necessary social and economic
changes.
Thomas Malthus
At the beginning of the Industrial Revolution in
the late 1700s, there were some economists and
intellectuals who saw what was happening.24
They understood that resources were limited and
human population would one day outstrip its
resources.
California Brown Pelican
Pelecanus occidentalis californicus
21
Progress to Ponting is a very destructive way of
viewing human interactions with the environment
because economists:11
What Were the More Serious Environmental
and Social Problems Created in This Period?
1. The Sixth Extinction
…ignore the problem of resource depletion
and deal only with the secondary problem
of the distribution of resources between
different competing ends. The crucial effect
is that the earth’s resources are treated as
capital—a set of assets to be turned into a
source of profit. Trees, wildlife, minerals,
water and soil are treated as commodities to
be sold or developed …Yet this view overlooks the basic truth that the resources of
the earth are not just scarce, they are
finite (emphasis added).
There have been five periods in Earth’s history
when extremely rapid changes have taken place
in which a great majority of the species present at
each event became extinct (Teacher Information
page 48). Several authors are saying the rapid extinction of animals and plants on Earth today is
the “sixth extinction.” 12,26,27 In fact, the rate of extinction today is higher than any period since the
demise of the dinosaurs 65 million years ago. The
cause this time is not a meteor or comet crashing
into the earth or volcanic ash darkening the atmosphere. It is from human actions all over the world.
An economist back in Malthus’ time agreed with
him that some day we will need to have a “steady
state” economy. This is now referred to as a “sustainable” economy. Natural capital, both renewable and non-renewable, is now becoming scarce
and a sustainable economic system is needed.25
The removal by humans of considerable amounts
of energy that would be otherwise available to
other species is out of proportion. Two hundred
years ago humans were removing about one
Sustainability means population and consumption
must be at the level where we do not overuse our
renewable resources; otherwise, they become
non-renewable, or degrade the habitat causing extinction of animals. We must not degrade our lifesupport ecosystems (Teacher Information page
48).
Near the end of the Industrial Revolution in 1948,
Bernard Baruch, financier and statesman, made
this statement about the overuse of “resource
capital:” 1
Because of the great abundance of the earth’s
resources we have taken them for granted.
But now, over most of the globe, —we are
face to face with a serious depletion of “resource capital.” More than one country is
already bankrupt. Such bankruptcy has
wiped out civilizations in the past; there is
no reason for thinking we can escape the
same fate, unless we change our ways.
©Scott Miller
“What’s that you’re wearing?”
Cold weather was bad for the dinosaurs, but good
for mammals. They appeared about the same
time the dinosaurs were disappearing.
22
hands of humans, especially in Australia and the
Americas. Animals which had never seen humans
before were unafraid and were easy victims to the
spears and clubs of the new arrivals. It was not
because of the bow and arrow. They were not invented until these species had disappeared. The
extermination of large mammals by humans such
as the giant ground sloth and mammoths took place
in the Western Hemisphere after the arrival of the
first waves of humans about 15,000 years ago.12
2. Reasons For The Population Explosion
• The discovery of the Western Hemisphere
changed population trends considerably. Foods
grown here, namely the potato and corn, spread
quickly around the world. Many people in dense
human populations in other countries
migrated to the vast lands of South and North
America. In those unexploited lands, large
families and in-migration supplied workers for
farm and industry.
Woolly Mammoth
Extinct at the hands of humans
percent of the annual energy produced by photosynthesis in plants. There were few extinctions
then. Today about 40 percent of all the primary
productivity on land is now being destroyed,
burned, or eaten by us and our domesticated
animals each year.28 This means that all “wild”
species are now receiving 40 percent less energy
than was available to them just a short time ago.
Species cannot evolve fast enough to compensate
for this rapid loss of energy and habitat. Other
causes of extinction include pollution,
overutilization, and habitat loss.
• With seemingly great opportunities for the future, people have larger families. This is called
the “euphoria” effect. Euphoria is a feeling of high
spirits and well being.
• There was improved health and more people
lived longer which added to the population
explosion.
Humans have exterminated species before now.
Animals which evolved over a million or so years
in areas where humans lived had an inherited fear
behavior which protected them from this new
predator on the scene. Giant mammals in Africa
persisted and live today through this adjustment.
In the Western Hemisphere, some large mammals
that coexisted with the human migration from Asia
were able to co-exist. Their ancestors evolved with
the fear of humans before they came to the
Western Hemisphere, over the Bering Strait, millions of years before humans. Some of these were
the musk ox, bison, caribou, and antelope.
• In some poor countries, family size increased
because of the prospect of escaping from centuries of poverty.7
However, several giant mammal species which did
not evolve with humans became extinct at the
Giant Glyptodont
Extinct at the hands of humans
23
However, when people in these countries, especially in sub-Saharan Africa (the countries south
of the Saharan desert) realized “progress” was not
happening, they then continued to have large families for old-age security. The poor countries when
they were colonies, and those that became independent after 1945, did not have the means of
social security and welfare programs to care for
old and unprotected people.29
farming produced food for two billion additional
people.
How was this done? Higher yields of grains and
fruit were achieved by genetic changes in plants,
new fertilizers, increased irrigation by pumping
from underground aquifers, and use of pesticides.
The photosynthetic energy of plants goes to the
roots, stems, leaves, and reproductive parts—the
seeds and fruits. Plant scientists have been able to
transfer energy which would normally go to the
leaves and roots to seed production, greatly
increasing the yield of grains (see page 27).
People all over the world, but especially in Africa, Central America, South America, and Asia
where few welfare programs exist, have “many
sons” to ensure the elderly will be provided with
support and help when they can no longer support
themselves.
• Bride Price and Dowry
The Green Revolution has come to an End
This technological advance has its limitations—
we have just about reached the maximum increased yield in this manner. Biogenetic engineers
think they can produce more grain yield this way,
but there is not much more they can force out of
the plants.31 Fertilizers, pesticides, and irrigation
have reached their peak.
30
Bride Price. When married, sons stay at home
and the young wife moves in with the husband’s
family. Bride price means the family of the son
(or the son) must “pay” his wife’s family for her.
This can be in money, gold, cattle, and other
wealth. If you had a son, not only would he
remain in the family, but his wife would become
part of the son’s family for more security.
Who did the Green Revolution Benefit?
Norman Myers, an ecologist, made this statement
in 1993 about the Green Revolution:32 “We have
not fed hungry people more, we have fed more
hungry people.”
Dowry. In this case the parents of a young woman
collect valuables to pay to the husband or
husband’s family to take their daughter.. The girls’
parents not only lose part of their security and work
for the family, but they also need to amass wealth
to “buy” her a “good” husband.
What did he mean by this? First, the population
increased by almost 2 billion people in the time
between 1955 and 1985. Since there was an increase of food for 2 billion people it would seem
that on the average each person would eat about
the same amount. But this was not the case. Most
of the increase in population was among the very
poor, and many of them could not afford to buy
Either the bride price or the dowry leaves the
wife’s family with less old-age security. The
bride’s family then may keep having children until they feel they have enough sons to support them.
In countries with high child mortality, women
commonly may have more than five children.
breeding plumage
3. The Green Revolution
A spectacular agricultural expansion occurred over
the last part of the Industrial Revolution into the
Environmental Revolution, from 1955 to about
1985. During this 30 year period, scientific
winter plumage
Marbled Murrelet
Brachyramphus marmoratus
24
the additional food raised by more expensive technology. To repeat, “…we fed more hungry people.”
increasing, we will continue to try to keep up
and will not succeed.
Historian Clive Ponting11 elaborates on this:
We leave the Industrial Revolution with this statement written in 1977 by economist Kenneth
Boulding:33
The ‘Green Revolution’ was hailed as the
solution to the problem of growing enough
food to support the expanding population of
the Third World. It has since become apparent that this is not the case. The impact of
these high-yielding varieties on the overwhelming majority of people in the Third
World has, in practice, been disastrous. The
problem with the new types of wheat and
rice is that in order to produce high yields,
they require large amounts of fertilizer and
also, because they lack natural immunity to
pests, large quantities of pesticides.
Present technology is based very heavily on
exhaustible resources and energy supplies,
and uses the reservoirs of air, land, and water for waste disposal. Both resources and
reservoirs are limited. If one resource starts
to run out, another can be substituted for
it,—but it, too, is exhaustible.
D. THE ENVIRONMENTAL
REVOLUTION—1960
The environmental situation qualifies as a “Revolution” because of the major changes which must
take place. It is a worldwide movement, and time
is running out to accomplish what must be done.
Lester Brown of the Worldwatch Institute warns
us: 34
The financial cost of growing the new
varieties was therefore much higher than for
the types of plant that had been grown for
generations. This meant that only those
farmers who could afford the higher inputs
could hope to achieve the higher yields and
the ‘Green Revolution’ therefore accentuated existing social differences and accelerated trends towards greater mechanization
and larger holdings. Small peasant farmers
(the majority) did not have enough land and
capital to make it worthwhile adopting the
new types, and the large landowners, who
had the necessary resources, were able to
become richer, expand their holdings, buy
up peasant land and turn the peasants into
landless laborers.
The Agricultural Revolution began some
10,000 years ago; the Industrial Revolution
has been under way for two centuries. But
if the Environmental Revolution is to
succeed, it must be compressed into a few
decades.
In Mexico, 80 percent of the extra production from the new types of wheat came from
just 3 percent of the total number of farms;
the average numbers of days worked every
year by the landless laborers fell from 194
to 100 and their real income fell by a fifth.
The Industrial Revolution ended with the Green
Revolution. The Green Revolution was short lived,
as “fixes” usually are, because the increase
in population overwhelmed technology and
innovations. Until the human population stops
Bald Eagle
Haliaeetus leucocephalus
25
The World Scene in the 1960s
businesses or raise crops with other women to
achieve economical security. When this happens,
women have smaller families.36,37
Many social issues in the United States were causing unrest and people demanded solutions. The
most essential and significant of these issues were
the civil rights, anti-war, and women’s rights
movements. The environmental movement added
an important concern about global problems, and
it blended with the others, creating a truly revolutionary time in history.
Women’s ability to plan for smaller families is
being helped in some Islamic countries. The new
religious leader in Iran has proclaimed that there
is nothing in the Koran which says that women
are not equal to men, and nothing that prevents
men and women from using contraceptives. This
is also happening in several other Islamic
countries.
1. Women’s rights and equality, especially reproductive rights, are vital for today’s social
and environmental betterment.
The reason Iran, as well as Oman, is concerned
about family size is that in about 40 years Iran (20
years for Oman) will run out of oil. At that time
they will lose most of their income from other
countries and people will be unemployed. To get
a marriage license in Iran a young couple must
now take a family planning course. The governments of Oman, Turkey, Bangladesh, and Iran, all
dominantly Islam countries, are very concerned
about their large family size. The 1994 and 1999
average family sizes for these countries are:
Turkey: 3.5 and 2.6; Bangladesh: 4.9 and 3.3; Iran:
6.6 and 3.0; Oman: 6.9 and 7.1.
Here in the United States and most developed
countries, there is a high level of women’s rights
and equality. However, in most developing countries there are economic inequality, male dominance, and other cultural barriers which keep
women poorly educated, and overburdened with
children.
These women have little decision-making opportunities. For the poorest, their duties are to have
children, raise crops, cook, milk animals, and
gather firewood, etc. These are all very necessary
in keeping their society moving. But economics,
custom, and religion may keep women from controlling their fertility even when they do have an
education.
International women’s organizations and United
Nations agencies are assisting women in developing countries to educate and help those who are
asking for help. This is primarily to have smaller
families and to be able to gain economic and
social status in their community. Family size is
already dropping in these areas.
Brian Walker, of Oxfam International, a humanitarian organization, states: 35
Worldwide, the most powerful inhibitors to
slowing population growth—the ones that
are least understood by policy makers—are
cultural, including people’s view of God, ancestor worship, lineage, the purpose of the
family, witchcraft, marriage, and polygamy.
In the poor societies, there are at least 100 million
women (some estimates are 500 million) who do
not want large families, and are asking assistance
from people in more affluent countries to help
them. There are many programs now underway
to give small loans to women to establish small
Steller Sea Lion
Eumetopias jubatus
26
2. Food
Malnutrition weakens the body’s immune system
to the point where common childhood ailments
such as measles and diarrhea often become fatal.
Every day 19,000 children die as a result of malnutrition and related illnesses.38
Many people feel that human carrying capacity is
involved only with starvation and hunger. As noted
above, food scarcity is only one of many reasons
for overpopulation. However, food is now becoming a major one. There are some reports that indicate there is enough food for many more billions
of people on earth and the problem is merely distribution. Distribution is part of the problem. But
even with a perfect distribution of food, there will
not be adequate food for the high estimates of 10
to 12 billion people (see below) in the future.
• Today, an estimated 841 million people remain
hungry and undernourished. This represents about
14 percent of the world’s population—one out of
every seven people on earth.38
• A study was made in 198839 which showed that
if everyone in the world ate like we do in the US,
where about 25% of our diet is meat, the world’s
food production could carry only about 2.5
billion people. If everyone was a vegetarian, the
earth could feed a healthy full diet for about six
billion people. This assumes that the pastoral livestock herders (see page 17) in the semi-arid lands
of the world also become vegetarians, which is
not possible.
• Soils are eroding throughout the world. Deserts
are forming from overgrazing. Irrigated lands are
becoming salty and waterlogged. Water is becoming scarce for irrigation. The technologies of the
Green Revolution (fertilizers, pesticides, genetic
increase in seed production) are now providing
little gain in crop yields. Natural limits are being
reached. Much of the land around the world is
In China and India, areas where the people
are becoming more secure and can afford it,
they are switching from a primarily vegetable
and grain diet to a more meat diet.
We are now at 6 billion people, and food from
now on will become a serious limiting factor
for humans. There is great hope that biotechnology (genetic improvements) will solve this
food problem. It may help, but not much more
can be extracted from the plants. Lester
Brown relates:40
On the genetic front, the principal growth
has come from redistributing the share of
the plant’s photosynthetic product (photosynthate) going to each of the various plant
parts (leaves, stems, roots, and seeds), so that
a much larger share goes to the seed—the
part used for food. Scientists estimate that
the originally domesticated wheats devoted
roughly 20 percent of their photosynthate
to the development of seeds. They were
stalk-heavy and harvest-light. Through plant
breeding, scientists have raised the share of
photosynthate going into seed—the ‘harvest
being used up for other purposes such as factories, subdivisions, and roads. Jungle soils are infertile and can be used only about 15 years after
clearing for crops. There are only a few new lands
available with good soil to increase cropland.
Eleven of the 15 ocean fisheries are now depleted
and the others are fully exploited.38
• Ten times more people die from malnutrition in
the world than from starvation. Malnutrition and
undernutrition reduce the resistance to diseases,
especially in children. However, most often
the deaths are not attributed to lack of food.
27
index’ —in today’s wheat, rice, and corn to
more than 50 percent. Given the plant’s basic requirements of an adequate root system,
a strong stem, and sufficient leaves for photosynthesis, scientists believe the physiological limit is around 60 percent.
TABLE 4. Percent of Vertebrate Groups
Threatened with Extinction
Group
Percent
Threatened
Birds
Mammals
Reptiles
Amphibians
Fishes
3. Latest information from Worldwatch
Institute publications
Here are some brief comments on additional environmental/population problems from recent
Worldwatch publications.
11
25
20
25
34
Total Species
Estimated on
Earth
Species
Used in
Survey
10,000
4,400
6,300
4,000
24,000
9,615
4,355
1,277
497
2,158
Source: Tuxill, 199842
Water41
Here are some examples of species lost in certain
areas:42
Water tables are falling on every continent,
including major food-producing regions.
Among those where aquifers are being depleted are in the US southern Great Plains;
the North China Plain, which produces
nearly 40 percent of China’s grain; and most
of India. …In both China and India, the two
countries that together dominate world
irrigation agriculture, substantial cutbacks
in irrigation water supplies lie ahead.
In Australia, 77 mammal species found nowhere else are currently threatened or already extinct, reflecting major changes in
the terrestrial habitats of that continent. East
Africa’s Lake Victoria—the worlds second
largest freshwater lake—appears to have lost
over 60 percent of its 300-plus species of
unique cichlid fishes beginning in the 1980s,
following the intentional introduction of the
predatory Nile perch. And scientists now believe that more than 2,000 bird species vanished in a wave of extinctions as human
populations first settled the Pacific Island
chains between 3,000 and 1,000 years ago—
a progressive decline that continues even
today on many archipelagos.
Since it takes at least 1,000 tons of water to
produce a ton of grain, importing grain
becomes the most efficient way to import
water.
Biodiversity42
We live amid the greatest extinction of plant and
animal life since the dinosaurs disappeared some
65 million years ago, with species losses at 100 to
1,000 times the background rate. But humans are
not just witnesses to a rare historic event, we are
actually its cause. The leading sources of today’s
species loss—habitat alteration, invasions by exotic species, pollution, and overhunting—are all
functions of human activities.
Climate Change 41
All major scientific bodies acknowledge the
likelihood that climate change due to the
buildup of greenhouse gases in the atmosphere is indeed under way. The 15 warmest years on record have all occurred since
1979. The destabilization of our climate
threatens more intense heat waves, more
severe droughts and floods, more destructive storms, and more extensive forest fires.
…Fossil fuel use accounts for roughly three
quarters of world carbon emissions.
The greatest percentage of any group of vertebrates
(animals with backbones) which are threatened
with extinction are the fishes (Table 4).
28
Cropland41
Carbon emissions per person since 1950 show a
steady increase, a leveling off and then an increase
in the future (Figure 7). This curve closely
follows the average temperature of the earth’s
surface (Figure 8).
Since mid-century, population has grown
much faster than the cropland area. Grain
area has increased by some 19 percent, but
global population has grown by 132 percent,
seven times faster. As grain area per person
falls, more and more nations risk losing the
capacity to feed themselves.
In addition to per capita losses, population
growth can lead to degradation of cropland,
reducing its productivity or even eliminating it from production. As a country’s population density increases and good farmland
becomes scarce, poor farmers are forced
onto ecologically vulnerable land such as
hillsides and tropical forests (Figure 9).
Figure 7. Global carbon emissions per
person 1950–97, with projections to 205041
Deforestation and other land use changes
account for the remainder of world carbon
emissions. Forests have served as a sink for
carbon throughout much of human history.
In recent years, however, the world’s forests have become net sources of atmosphere
carbon, largely due to forest burning and
clearing in the tropics. Six months of fires
in Asia in 1997 and 1998 released more carbon than Western Europe emits from fossil
fuel burning in an entire year.43
Figure 9. World grain harvested area per
person,1950–1998, with projections to 205043
Santa Cruz Cypress
Cupressus abramsiana
Figure 8. Average temperature at the
earth’s surface, 1866–199841
29
Forests 41
Global use of paper and paperboard per
person, has nearly tripled since 1961, and
most of the increase had come in wealthy
countries with low or even stable levels of
population. Forests provide services vital to
a local population, such as control of erosion, steady provision of water across rainy
and dry seasons, and regulation of rainfall.
Taken together, the loss of these services due
to deforestation can upset local economics
and subject local populations to economic
instability.
Southern Sea Otter
Enhydra lutris nereis
Meat Production 41
Historically, growth in the world meat supply came primarily from beef and mutton,
sustained by the world’s rangelands. These
areas, consisting mostly of land that is too
arid to support crop production, over a vast
part of the planet, roughly double the cropland area. Not only do the herds of cattle
and flocks of sheep and goats produce meat
and milk, but for millions of people in
Africa, the Middle East, Central Asia, parts
of the Indian subcontinent, and western
China, they provide a livelihood. The feasible way that this land can contribute to the
world’s food supply is to graze cattle, sheep
and goats, producing the meat and milk that
directly and indirectly sustains a large
segment of humanity.
Urbanization 43
In 1800, only one city - London - had a million people. Today, 326 cities have at least
that many people. Tokyo is the largest, at 28
million. Mexico City is second, at 18
million. Bombay, Sao Paulo, and New York
are close behind, with 17 million each.
Rounding out the list in descending size are
Shanghai (14 million), Calcutta (13), Los
Angeles (12), Buenos Aires (12), Seoul (12),
Beijing (12), Lagos (12), Osaka (11), Delhi
(11), Rio de Janeiro (10), and Dhaka (10).
California Condor
Gymnopgyps
californianus
The relative conversion efficiency of various animals begins to influence production
trends. Producing a kilogram of beef in the
feedlot requires roughly seven kilograms
of grain, while a kilogram of pork requires
nearly four of grain and a kilogram of poultry, just over two. This helps explain why
world poultry production overtook that of
beef in 1996.
d. Other Environmental Issues Included in the
Teacher Information Section. These are descriptions of ecosystems, ozone layer depletion,
global warming, the coming fuel crisis, the sixth
extinction, and Navajo pastoralism.
30
IV. WHAT NEEDS TO BE DONE?
that environmentally we are overpopulated.
Everyone needs to keep informed about what is
happening with the environment and population.
Things are changing fast. Some types of information several years old are no longer valid.
• Globally, the importance of small families cannot be exaggerated. There is no way to get people
out of poverty and for women to gain economic
and social status in developing countries unless
the population is reduced through voluntary reduction of family size. Attempts to improve living conditions are constantly being erased by the
increase of population.
• Population numbers and the trends of family
size and population change rapidly. Global information sources are listed on pages 69-70.
• The status of the resources in the world are
changeable, especially food production, forest
cover, cropland, and degrees of hunger and
famines.
• There are many sources of reliable scientific
information listed in the reference section of this
syllabus. But, be very careful with what you read
on the web. There is good information. There also
may be information which is intended to confuse
the public and lead us to wrong conclusions. A
growing number of individuals and organizations
do not care about the future. They want to get as
much of the remaining resources as they can for
immediate profit.
• Local environmental and population problems
change. There will be an increased demand for
forest products and for conversion of cropland into
other uses. Our wildlife ecosystems must be protected for watershed and to prevent soil erosion.
We also need them for wildlife enjoyment and
survival of species on whose well-being and
interrelatedness we depend.
• Educate yourself, educate others, and become
active in local conservation and population
problems.
• Local programs to recycle, reduce and reuse
are essential for two reasons: they lower the consumption of resources, and they teach everyone
that resources are limited. It is a constant reminder
• There is great hope that enough people in the
world with accurate information will prevail and
turn us toward a better life and a better world.
©Scott Miller
31
32