A
Malthusian catastrophe (also known as
Malthusian check) was a prediction of a forced return to subsistence-level conditions once population growth had outpaced agricultural production.
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.
Contents
- 1 Work by Thomas Malthus
- 2 Neo-Malthusian theory
- 3 Criticism
Work by Thomas Malthus
In 1798, Thomas Malthus published An Essay on the Principle of Population, in which he wrote:
The power of population is so superior to the power of the earth to
produce subsistence for man, that premature death must in some shape or
other visit the human race. The vices of mankind are active and able
ministers of depopulation. They are the precursors in the great army of
destruction, and often finish the dreadful work themselves. But should
they fail in this war of extermination, sickly seasons, epidemics,
pestilence, and plague advance in terrific array, and sweep off their
thousands and tens of thousands. Should success be still incomplete,
gigantic inevitable famine stalks in the rear, and with one mighty blow
levels the population with the food of the world.
—Malthus T.R. 1798. An essay on the principle of population. Chapter VII, p61[1]
Notwithstanding the apocalyptic image conveyed by this particular
paragraph, Malthus himself did not subscribe to the notion that mankind
was fated for a "catastrophe" due to population overshooting resources.
Rather, he believed that population growth was generally restricted by
available resources:
The passion between the sexes has appeared in every age to be so
nearly the same that it may always be considered, in algebraic language,
as a given quantity. The great law of necessity which prevents
population from increasing in any country beyond the food which it can
either produce or acquire, is a law so open to our view...that we cannot
for a moment doubt it. The different modes which nature takes to
prevent or repress a redundant population do not appear, indeed, to us
so certain and regular, but though we cannot always predict the mode we
may with certainty predict the fact.
—Malthus, 1798, Chapter IV.
Neo-Malthusian theory
Wheat yields in developing countries, 1950 to 2004, in kg/ha
(baseline 500). The steep rise in crop yields in the U.S. began in the
1940s. The percentage of growth was fastest in the early rapid growth
stage. In developing countries maize yields are still rapidly rising.
[2]
After World War II, mechanized agriculture produced a dramatic increase in productivity of agriculture and the so-called Green Revolution
greatly increased crop yields, expanding the world's food supply while
lowering food prices. In response, the growth rate of the world's
population accelerated rapidly, resulting in predictions by Paul R. Ehrlich, Simon Hopkins,[3]
and many others of an imminent Malthusian catastrophe. However,
populations of most developed countries grew slowly enough to be
outpaced by gains in productivity.
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, increased urbanization, and a wider availability of effective birth control, causing the demographic-economic paradox.
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.[4]
World population from 1800 to 2100, based on UN 2004 projections (red, orange, green) and US Census Bureau historical estimates (black)
Growth in food production has been greater than population growth. Food
per person increased during the 1961–2005 period, but at a much smaller
percentage than crop yields.
Historians have estimated the total human population back to 10,000 BC.[5]
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).[4]
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 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.[6]
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.
The graph of annual growth rates (above) 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.[6] Also visible on this graph are the effects of the Great Depression, the two world wars, and possibly also the 1918 flu pandemic.
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.[7]
Criticism
Ester Boserup 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
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.[10]
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.[11]
Friedrich Engels
also criticizes the Malthusian catastrophe because Malthus failed to
see that surplus population is connected to surplus wealth, surplus
capital, and surplus landed property. Population is large where the
overall productive power is large. Engels also states that the
calculation that Malthus made with the difference in population and
productive power is incorrect because Malthus does not take into
consideration a third element, science. Scientific “progress is as
unlimited and at least as rapid as that of population”.[12] On the other hand, Joseph Tainter argues that science has diminishing marginal returns[13] and scientific progress is becoming more difficult, harder to achieve and costlier.
