Malthusian theory
Introduction
In 1798, Thomas Malthus published An Essay on the Principle of Population,
describing his theory of quantitative development of human populations: he fairly makes
two postulata: First, That food is necessary to the existence of man. Secondly, that the
passion between the sexes is necessary and will remain nearly in its present state. These
two laws, ever since we have had any knowledge of mankind, appear to have been fixed
laws of our nature, and, as we have not hitherto seen any alteration in them, we have no
right to conclude that they will ever cease to be what they now are, without an immediate
act of power in that Being who first arranged the system of the universe, and for the
advantage of his creatures, still executes, according to fixed laws, all its various
operations.
Assuming then his postulata is granted; he was saying then, that the power of
population is indefinitely greater than the power in the earth to produce subsistence for
man. Population, when unchecked, increases in a geometrical ratio. A series that is
increasing in geometric progression is defined by the fact that the ratio of any two
successive members of the sequence is a constant. For example, a population with an
average annual growth rate of, say, 2% will grow by a ratio of 1.02 per year. In other
words, the ratio of each year's population to the previous year's population will be 1.02.
In modern terminology, a population that is increasing in geometric progression is said to
be experiencing exponential growth. Alternately, in an arithmetic progression, any two
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successive members of the sequence have a constant difference. In modern terminology,
this is called linear growth.
If unchecked over a sufficient period of time, and if the ratio between successive
sequence members is larger than 1.0, then exponential growth will always outrun linear
growth. Malthus saw the difference between population growth and resource growth as
being analogous to this difference between exponential and linear growth. Even when a
population inhabits a new habitat – such as the American continent at Malthus' time, or
when recovering from wars and epidemic plagues – the growth of population will
eventually reach the limit of the resource base. (Malthus 1798).
Proponent
Thomas Robert Malthus (13 February 1766 – 23 December 1834), was a
British scholar, influential in political economy and demography. Malthus has become
widely known for his theories concerning population and its increase or decrease in
response to various factors. Malthus thought that the dangers of population growth would
preclude endless progress towards a utopian society: "The power of population is
indefinitely greater than the power in the earth to produce subsistence for man". As an
Anglican clergyman, Malthus saw this situation as divinely imposed to teach virtuous
behaviour. Believing that one could not change human nature (http:// en.wikipedia.org/).
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Neo-Malthusian theory
It originates from the ideas of Thomas Robert Malthus. The Malthusian theory
suggests a relationship between the growth of population and food. Thomas Malthus
argued that population growth is geometric (1→2→4→8), and agricultural growth is
arithmetic (1→2→3→4); therefore, population growth will increase at such a rate that
eventually there will not be enough food for the population.
The rapid increase in the global population of the past century (and its continued
increase) complements Malthus' predicted population patterns; it also appears to describe
sociodemographic dynamics of complex pre-industrial societies. These findings are the
basis for neo-malthusian modern mathematical models of long-term historical dynamics
(Peter Turchin 2003; Turchin and Korotayev 2006; Peter Turchin et al. 2007; Korotayev
et al. 2006).
Neo-malthusianism was originally used to mean population limitation by birth
control and/or abortion. Currently it may be used as a label for those who are concerned
that overpopulation may increase resource depletion or environmental degradation to a
degree that is not sustainable with the potential of ecological collapse or other hazards.
(http://en.wikipedia.org/wiki/Neo-Malthusianism).
Proponent
Paul Ralph Ehrlich (born 29 May 1932) is an American biologist and
educator who is the Bing Professor of Population Studies in the department of Biological
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Sciences at Stanford University and president of Stanford's Center for Conservation
Biology. By training he is an entomologist specializing in Lepidoptera (butterflies), but
he is better known as an ecologist and a demographer, specifically for his warnings about
unchecked population growth and limited resources. Ehrlich became a household name
after publication of his controversial 1968 book The Population Bomb. He is also known
for the famous Simon–Ehrlich wager, a bet he made with and lost to economist Julian
Simon.
Ehrlich was born in Philadelphia, Pennsylvania. His father was a shirt salesman,
his mother a Greek and Latin scholar. He earned a bachelor’s degree in zoology from the
University of Pennsylvania in 1953, an M.A. at the University of Kansas in 1955, and a
Ph.D. in 1957 at the University of Kansas, under the prominent bee researcher C.D.
Michener. During his studies he participated in surveys of insects on the Bering Sea and
in the Canadian Arctic, and then on a National Institutes of Health fellowship,
investigated the genetics and behavior of parasitic mites. In 1959 he joined the faculty at
Stanford, being promoted to full professor of biology in 1966. He was named to the Bing
Professorship in 1977, and he is president of the Center for Conservation Biology at
Stanford University. In addition, Ehrlich is a fellow of the American Association for the
Advancement of Science, the American Academy of Arts and Sciences and the American
Philosophical Society.
Ehrlich continues to conduct policy research on population and resource issues,
focusing especially on endangered species, cultural evolution, environmental ethics, and
the preservation of genetic resources. Along with Dr. Gretchen Daily, he has conducted
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work in countryside biogeography, or the study of making human-disturbed areas
hospitable to biodiversity. His research group at Stanford currently works extensively on
the study of natural populations of the Bay checkerspot butterfly (Euphydryas). He has
been married to Anne H. Ehrlich since 1954; he and Anne have one child, Lisa Marie.
Ehrlich is famous for positing three key factors that determine sustainability: population,
affluence and technology, and this have been summarized in the equation I PAT.
I PAT is the lettering of a formula put forward to describe the impact of human
activity on the environment. I = P × A × T: In words:
Human Impact (I) on the
environment equals the product of population (P), affluence (A: consumption per capita)
and technology (T: environmental impact per unit of consumption). This describes how
our growing population, affluence, and technology contribute toward our environmental
impact. The equation was developed in the 1970s during the course of a debate between
Barry Commoner, Paul R. Ehrlich and John Holdren.
Commoner argued that
environmental impacts in the United States were caused primarily by changes in its
production technology following World War II, while Ehrlich and Holdren argued that all
three factors were important and emphasized in particular the role of population growth.
(PR
Ehrlich,
JP
Holdren,
Impact
of
population
growth,
Science,
1971)
(http://en.wikipedia.org/wiki/I_PAT).
Peter Turchin was born in Obninsk, Russia, in 1957 and in 1963 moved to
Moscow. In 1975 he entered the Faculty of Biology of the Moscow State University and
studied there until 1977, when his father, the Soviet dissident Valentin Turchin, was
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exiled from the USSR. He got his B.A. in biology from the New York University (cum
laude) in 1980 and Ph.D. in zoology in 1985 from Duke University.
Professor at the
University of Connecticut in the Department of Ecology and Evolutionary Biology as
well as in the Department of Mathematics. He has made contributions to population
ecology and historical dynamics. According to ISIHighlyCited.com, Turchin is one of the
top cited authors in the field of Ecology/Environment. He is one of the founders of
cliodynamics, the new scientific discipline located at the intersection of historical
macrosociology, cliometrics, and mathematical modelling of social processes. Turchin
developed an original theory explaining how large historical empires evolve by the
mechanism of multilevel selection. His research on secular cycles has contributed to our
understanding of the collapse of complex societies as has his re-interpretation of Ibn
Khaldun's asabiyya notion as "collective solidarity" (http:// en.wikipedia.org/).
Assumptions/Hypothesis
Neo-Malthusian theory argues that unless at or below subsistence level, a
population's fertility will tend to move upwards. Assume for example that a country has
10 breeding groups. Over time this country's fertility will approach that of its fastest
growing group in the same way that will eventually come to resemble regardless of how
large the constant a is or how small the constant b is. Under subsistence conditions the
fastest growing group is likely to be that group progressing most rapidly in agricultural
technology. However, in above-subsistence conditions the fastest growing group is likely
to be the one with the highest fertility. Therefore the fertility of the country will approach
that of its most fertile group. This, however, is only part of the problem.
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In any group some individuals will be more pro-fertility in their beliefs and
practices than others. According to neo-Malthusian theory, these pro-fertility individuals
will not only have more children, but also pass their pro-fertility on to their children,
meaning a constant selection for pro-fertility similar to the constant natural selection for
fertility genes (except much faster because of greater diversity). According to neoMalthusians, this increase in fertility will lead to hyper exponential population growth
that will eventually outstrip growth in economic production. This appears to make any
sort of voluntary fertility control futile, in the long run. Neo-Malthusians argue that
although adult immigrants (who, at the very least, arrive with human capital) contribute
to economic production, there is little or no increase in economic production from
increased natural growth and fertility. Neo-Malthusians argue that hyper exponential
population growth has begun or will begin soon in developed countries.
To this can be added that farmland deteriorates with use. Some areas where there
was intensive agriculture in classic times (i.e., the feudal era) had already declined in
population because their farmland was worn out, long before he wrote. At the time
Malthus wrote, and for 150 years thereafter, most societies had populations at or beyond
their agricultural limits. After World War II, the so-called Green Revolution produced a
dramatic increase in productivity of agriculture, and, consequently, growth of the world's
food supply. In response, the growth rate of the world's population accelerated rapidly,
resulting in predictions by Paul R. Ehrlich, Simon Hopkins, and many others of an
imminent Malthusian catastrophe. However, populations of most developed countries
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grew slowly enough to be outpaced by gains in productivity. By 1990, agricultural
production appeared to begin peaking in several world regions (http://en.wikipedia.org/).
By the early 21st century, many technologically developed countries had passed
through the demographic transition, a complex social development encompassing a drop
in total fertility rates in response to lower infant mortality, more education of women,
increased urbanization, feminizing caused massive defathering and a wider availability of
effective birth control, causing the demographic-economic paradox. Developed and
developing countries follow two distinct paths. Most developed countries have sufficient
food supply, low fertility rates, and stable (in some cases even declining) populations. In
some cases, population growth occurs due to increasing life expectancies, even though
fertility rates are below replacement. For example, as of 2008, Spain has approximately
4.6 km2 of arable land or permanent crops per 1,000 residents, and its average fertility
rate is well below replacement level (1.3 children/woman). Its population has grown less
than 50% in the last 40 years. The corresponding ratio for Nigeria is only 2.1 km2 of
arable land or crops per 1,000 residents; Nigerian total fertility rate is 5.0
children/woman, and its population has more than tripled during the same 40 years. The
Malthusian catastrophe appears to have been temporarily averted in Spain, although the
Neo-Malthusian theory argues that the situation is only temporary; on the other hand, a
significant part of population of Nigeria lives near subsistence levels.
David Pimentel and Ron Nielsen, working independently, determined that the
human population as a whole has passed the numerical point where all can live in
comfort, and that we have entered a stage where many of the world's citizens and future
8
generations are trapped in misery. There is evidence that a catastrophe is underway as of
at least the 1990s; for example, by the year 2000, children in developing countries were
dying at the rate of approximately 11,000,000 per annum from strictly preventable
diseases. These data suggest that, by the standard of misery, the catastrophe is underway.
The term 'misery' can generally be construed as: high infant mortality, low standards of
sanitation, malnutrition, inadequate drinking water, widespread diseases, war, and
political unrest (http://en.wikipedia.org/).
Regarding famines, data demonstrate the world's food production has peaked in
some of the very regions where food is needed the most. For example, in South Asia,
approximately half of the land has been degraded such that it no longer has the capacity
for food production. In China there has been a 27% irreversible loss of land for
agriculture, and it continues to lose arable land at the rate of 2,500 square kilometres per
year.
In Madagascar, at least 30% of the land previously regarded as arable is
irreversibly barren. On the other hand, recent data show the number of overweight people
in the world now outnumbers that of malnourished, and the rising tide of obesity
continues to expand in both rich and poor countries (http://en.wikipedia.org).
On the assumption that the demographic transition is now spreading from the
developed countries to less developed countries, the United Nations Population Fund
estimates that human population may peak in the late 21st century rather than continue to
grow until it has exhausted available resources. Some have expressed doubt about the
validity of the UN projections, claiming that they are below the projections by others.
The most important point is that none of the projections show the population growth
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beginning to decline before 2050. Indeed, the UN "high" estimate does not decline at all,
even
out
to
2300,
indicating
the
potential
for
a
Malthusian
catastrophe
(http://en.wikipedia.org).
The actual growth curve of the human population is another issue. In the latter
part of the 20th century, many argued that it followed exponential growth; however, a
more recent view is that the growth in the last millennium has been faster, at a
superexponential (possibly hyperbolic, double-exponential, or hyper-exponential) rate.
Alternatively, the apparently exponential portion of the human population growth curve
may actually fit the lower limb of a logistic curve.
World population from 1800 to 2100 based on UN 2004 projections (red, orange, green)
and US Census Bureau historical estimates (black).
Historians have estimated the total human population on earth back to 10,000 BC.
The figure on the right shows the trend of total population from 1800 to 2005 and from
there in three projections out to 2100 (low, medium, and high). The second figure shows
the annual growth rate over the same period. If population growth were exactly
exponential, then the growth rate would be a flat line. The fact that it was increasing from
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1920 to 1960 indicates faster-than-exponential growth over this period. However, the
growth rate has been decreasing since then, and is projected to continue decreasing. The
United Nations population projections out to 2100 (the red, orange, and green lines) show
a possible peak in the world's population occurring as early as 2040 in the most optimistic
scenario, and by 2075 in the "medium" scenario.
A chart of estimated annual growth rates in world population, 1800-2005. Rates before
1950 are annualized historical estimates from the US Census Bureau. Red = USCB
projections to 2025.
The graph of annual growth rates (below) does not appear exactly as one would
expect for long-term exponential growth. For exponential growth it should be a straight
line at constant height, whereas in fact the graph from 1800 to 2005 is dominated by an
enormous hump that began about 1920, peaked in the mid-1960s, and has been steadily
eroding away for the last 40 years. The sharp fluctuation between 1959 and 1960 was due
to the combined effects of the Great Leap Forward and a natural disaster in China. Also
visible on this graph are the effects of the Great Depression, the two world wars, and
possibly also the 1918 flu pandemic.
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Though short-term trends, even on the scale of decades or centuries, cannot prove
or disprove the existence of mechanisms promoting a Malthusian catastrophe over longer
periods, the prosperity of a small fraction of the human population at the beginning of the
21st century, and the debatability of ecological collapse made by Paul R. Ehrlich in the
1960s and 1970s, has led some people, such as economist Julian L. Simon, to question its
inevitability.
A 2004 study by a group of prominent economists and ecologists, including
Kenneth Arrow and Paul Ehrlich, suggests that the central concerns regarding
sustainability have shifted from population growth to the consumption/savings ratio, due
to shifts in population growth rates since the 1970s. Empirical estimates show that public
policy (taxes or the establishment of more complete property rights) can promote more
efficient consumption and investment that are sustainable in an ecological sense; that is,
given the current (relatively low) population growth rate, the Malthusian catastrophe can
be avoided by either a shift in consumer preferences or public policy that induces a
similar shift.
However, some contend that the Malthusian catastrophe is not imminent. A 2002
study by the UN Food and Agriculture Organization predicts that world food production
will be in excess of the needs of the human population by the year 2030; however, that
source also states that hundreds of millions will remain hungry (presumably due to
economic
realities
and
political
issues)
Malthusianism).
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(http://en.wikipedia.org/wiki/Neo-
Merit/demerit
A Malthusian catastrophe was originally foreseen to be a forced return to
subsistence-level conditions once population growth had outpaced agricultural
production. Later formulations consider economic growth limits as well. The term is also
commonly used in discussions of oil depletion. Based on the work of political economist
Thomas Malthus (1766–1834), theories of Malthusian catastrophe are very similar to the
Iron Law of Wages. The main difference is that the Malthusian theories predict what will
happen over several generations or centuries, whereas the Iron Law of Wages predicts
what will happen in a matter of years and decades. An August 2007 science review in
The New York Times raised the claim that the Industrial Revolution had enabled the
modern world to break out of the Malthusian Trap, while a front page Wall Street Journal
article in March 2008 pointed out various limited resources which may soon limit human
population growth because of a widespread belief in the importance of prosperity for
every individual and the rising consumption trends of large developing nations such as
China and India (http://en.wikipedia.org/wiki/Malthusian_catastrophe).
Ester Böserup wrote in her book The Conditions of Agricultural Growth: The
Economics of Agrarian Change under Population Pressure that population levels
determine agricultural methods, rather than agricultural methods determining population
(via food supply). A major point of her book is that "necessity is the mother of
invention".
Julian Simon was one of many economists who challenged the Malthusian
catastrophe, citing (1) the existence of new knowledge, and educated people to take
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advantage of it, and (2) "economic freedom", that is, the ability of the world to increase
production when there is a profitable opportunity to do so.
The economist Henry George argued that Malthus didn't provide any evidence of
a natural tendency for a population to overwhelm its ability to provide for itself. George
wrote that even the main body of Malthus' work refuted this theory; that examples given
show social causes for misery, such as "ignorance and greed... bad government, unjust
laws, or war," rather than insufficient food production (en.wikipedia.org/wiki/Malthusian
catastrophe).
Application to Rural Development
The equation can aid in understanding some of the factors affecting human
impacts on the environment. In the I=PAT equation, the variable P represents the
population of an area, such as the world. Since the rise of industrial societies, human
population has been increasing exponentially. This has caused Thomas Malthus and
many others, such as ecologist Garrett Hardin, to postulate that this growth would
continue until checked by widespread hunger and famine. The United Nations and the
US Census Bureau project that world population will increase from 6.8 billion today to
about 9.2 billion by 2050. These projections take into consideration that population
growth has slowed in recent years as women are having fewer children. This
phenomenon is believed to be a result of demographic transition in developed nations.
As a result, the UN believes that human population might stabilize around 9 billion by
2100. However, since the world population is set to keep rising for the next few decades,
this factor of the I=PAT equation will likely keep increasing human impact on the
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environment for the near future.
Increased population increases our environmental
impact in many ways, which include but are not limited to:

Increased land use - Results in habitat loss for other species.

Increased resource use - Results in changes in land cover

Increased pollution - Causes climate change, sickens people and damages
ecosystems.
The variable A, in the I=PAT equation stands for affluence. It represents the
average consumption of each person in the population. As the consumption of each
person increases, the total environmental impact increases as well. A common proxy for
measuring consumption is through GDP per capita. While GDP per capita measures
production, it is often assumed that consumption increases when production increases.
GDP per capita has been rising steadily over the last few centuries and is driving up
human impact in the I=PAT equation.
Environmental Impacts
Increased consumption significantly increases human environmental impact. This
is because as each product consumed has wide ranging effects on the environment. For
example, if the construction of a car had the following environmental impacts among
others:

605,664 gallons of water for parts and tires.

682 lbs. of pollution at a mine for the lead battery.

2178 lbs. of discharge into water supply for the 22 lbs. of copper contained in the
car.
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Then the more cars per capita, the greater the impact. Since the ecological impacts
of each product are so far reaching, increases in consumption quickly result in large
impacts on the environment.
Technology
The T variable in the I=PAT equation represents how resource intensive the
production of affluence is; how much environmental impact is involved in creating,
transporting and disposing of the goods, services and amenities used. Improvements in
efficiency can reduce resource intensiveness, reducing the T multiplier. Since technology
can affect environmental impact in many different ways, the unit for T is often tailored
for the situation I=PAT is being applied to. For example, for a situation where the human
impact on climate change is being measured, an appropriate unit for T might be
greenhouse gas emissions per unit of GDP.
Environmental Impacts
Increases in efficiency can reduce overall environmental impact. However, with P
increasing exponentially, T would have to decrease drastically (doubling efficiency each
time the population doubles) just to maintain the same impact with the same affluence.
Over the last few years, data from the UN World Bank has shown that T has decreased
and that it is likely to continue to do so in the future. However, since P has increased
exponentially, and A has also increased drastically, the overall environmental impact, I,
has still increased (http://en.wikipedia.org/wiki/Neo-Malthusianism).
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References
Korotayev, A., et al. 2006. Introduction to Social Macrodynamics. Moscow: KomKniga.
ISBN 5484005590
Thomas Malthus. An Essay on the Principle of Population, Posting Date: July 23, 2009
[EBook #4239] Release Date: July, 2003, First Posted: December 14, 2001, Last
Updated: June 30, 2007. http://www.gutenberg.net
Turchin, P., et al., eds. 2007. History & Mathematics: Historical Dynamics and
Development of Complex Societies. Moscow: KomKniga. ISBN 5484010020.
______(Undated). Population Dynamics and Internal Warfare: Reconsideration. Social
Evolution & History 5(2): 112–147.
http://en.wikipedia.org/wiki/I_PAT
ISIHighlyCited.com
http://en.wikipedia.org/wiki/Neo-Malthusianism
http://www.un.org/esa/population/publication/longrange2/worldPop 2300final.pdf
http://en.wikipedia.org/wiki/Malthusian_catastrophe
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