Malthus' argument focused on the rate of growth of human populations - specifically, those in the English colonies in the Americas - and on their ability to provide sufficient food resources. These excerpts from his essay lay out his basic assumptions and general conclusions.
I think I may fairly make 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....
Assuming then my postulata as granted, I say, 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. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison of the second.
Let us suppose that the product of the land might be increased every 25 years, by a quantity equal to what it at present produces. The most enthusiastic speculator cannot suppose a greater increase than this. Even then the land could not be made to increase faster than in an arithmetical ratio. Taking the whole earth, the human species would increase as the numbers 1, 2, 4, 8, 16, 32, 64, 128, 256, and subsistence as 1, 2, 3, 4, 5, 6, 7, 8, 9. In two centuries the population would be to the means of subsistence as 256 to 9; in three centuries as 4,096 to 13, and in two thousand years the difference would be almost incalculable.
Simply put, Malthus was saying that:
- a population's growth is geometric, or exponential; that it grows by a constant multiple of 2,
- the amount of available food grows arithmetically in a linear fashion - at best by the addition of a constant amount approximately every 25 years, and
- there will inevitably be a point of crisis where the population outgrows its capacity to produce food.
His argument is presented graphically at right.
1) What were the two characteristics of human behavior on which Malthus based his argument?
2) According to the Malthusian Growth graph and assuming a base year of 1700, when would the point of crisis in the competition between population growth and food supply occur in the English colonies?
3) Malthus pointed to the growth of the populations in the English colonies in the Americas in support of
his argument. Explore the accuracy of his hypothesis not only for
the English colonies, but for many of the Spanish and Portuguese
colonies in the Americas as well in the map below and in
the graphs in the following lesson.
The map consists of several layers for many of the countries of
the Americas and includes population data for years from 1650 to
2010 and staple food production data for the decades from the
1960s to 2010s.
(Note that the map shows current national boundaries.)
The pop-up for each country in the map includes a graph of population change over the last four centuries. Click on the colonies in Canada and the United States and examine the graphs. Was Malthus right about population growth in England's colonies being exponential during the colonial period? Was he right about population growth in the longer term from 1700 to today?
4) Use
the Change Style tool (
)
to change the population layer to show different time periods.
Where were the largest American populations in the first two
centuries following Columbus' voyages. How did the English
colonies compare?
5) The staple foods in one country are not necessarily those in others. Oats, for example is an important food in Canada, but not in Venezuela. Create a table listing all of the staple foods identified in the map. Briefly describe each food and identify 3-4 countries for each where the food is a staple.
6) Research the history of the potato and explain why the second highest level of production in the Americas is in Peru.
7) Select two countries in the Americas and look at the change in production of their staple foods. Was the change linear or exponential or something else? Explain.
8) Data
for each staple food includes the rate of change in production
from the 1960s thru the 2010s. Take Oat
production as an example. Click on the pop-up for the United
States and you will see that oat production fell by almost 88%
over the last five decades. Use the Oats
table ( 
) or pop-ups by country and explore oat production more
generally in the Americas. Is there a general pattern? Are
there any outliers? Explain.
Thomas Malthus, "An Essay on the Principle of Population, London: Printed for J. Johnson. 1798, Downloaded August 23, 2017 from Electronic Scholarly Publishing
Population data from Jonathan Fink-Jensen, Total
Population, (IISH Dataverse, 2015), downloaded
October 15, 2017.
Staple food data from FAOSTAT: Crops, (Food & Agricultural Organization of the United Nations, 2017) downloaded October 15, 2017