Lesson 3: Population Theories

Adapted from Rubenstein textbook, Chapter 2

Variations in Population Growth

The Demographic Transition Model

1. Low growth

2. High growth

3. Moderate growth

4. Low growth

Model predicts that all countries would over time go through four demographic transition stages.

The Demographic Transition

Fig. 2-13: The demographic transition consists of four stages, which move from high birth and death rates, to declines first in death rates then in birth rates, and finally to a stage of low birth and death rates. Population growth is most rapid in the second stage.

Demographic Transition in Britain

Fig. 2-14: England was one of the first countries to experience rapid population growth in the mid-eighteenth century, when it entered stage 2 of the demographic transition.

Limitations to DT ModelThe model is overly generalized to the European experience.The model is too rigid. It assumes that all countries go through

all four phases of demographic transition.The model does not take into account other variables, such as

war, political turmoil, etc.Question: Can contemporary less developed countries hope to

achieve either the demographic transition or the economic progress enjoyed by more developed countries that passed through the transition at a different time and under different circumstances? Why or why not?

Question? Is the socioeconomic change experienced by industrialized countries a prerequisite or a consequence of demographic transition? Explain

Thomas Malthus on Population ChangeIn 1798, he published the

Essay on the Principle of Population Populations grow

exponentially: i.e. 1, 2, 4, 16, 32, etc.

Food supply grows arithmetically: i.e. 1, 2, 3, 4, etc.

Consequence: eventually, the population will exceed the food supply capacity.

0

50

100

150

200

250

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1 2 3 4

Population

Food

Thomas Malthus on Population ChangeSo, population would

rise until it reaches its limits. Potential limits:Preventive checks -

postponement of marriage (lowering of fertility rate), increased cost of food, abortion, etc.

Positive checks - famine, war, disease, would increase the death rate.

Providing food and shelter to the poor -> population growth and increased poverty.

Population grows geometrically….

Population exceeds carrying capacity…

Population is kept in “check”– preventative and/or positive checks

Critiques on MalthusHumans can actually increase their own food supply –

productivity does not remain stagnant.Besides for this theories about helping the poor, can you

think of other critiques or do you think his basic premise is right?

Food & Population, 1950-2000Malthus vs. Actual Trends

Fig. 2-20: Malthus predicted population would grow faster than food production, but food production actually expanded faster than population in the 2nd half of the 20th century.

Will the World Face an Overpopulation Problem?

Yes: “The world's biggest problem? Too many people... Our unsustainable population levels

are depleting resources and denying a decent future to our descendants. We must stop the denial….Globally, the effects of overpopulation play a part in practically every daily report of mass human calamity…What to do? Stop the denial. Perpetual growth is the creed of a cancer cell, not a sustainable human society.” – Lost Angeles Times, July 21 2011

“World Bank president Robert McNamara has warned…they are doing too little to avoid a non-military threat that ranks in importance with thermonuclear war. The non-military threat he says is overpopulation – 11 billion people crammed into a world that now has trouble holding four billion.” – The Phoenix, April 30 1977

“Americans are starting to realize that the underdeveloped countries of the world face an inevitable population-food crisis..it now seems that it will continue to its logical conclusion: mass starvation…Of these poor, a minimum of ten million people , most of them children, will starve to death during each year of the 1970s…but this will be a mere handful compared to those that will be starving before the end of the century.” The Population Bomb 1968

Will the World Face an Overpopulation Problem?No “The World Is Not Overpopulated… The UN projects, under its medium-growth

scenario, that the human population will remain relatively stable at 9 billion until the year 2300.The reason is that birth rates are naturally falling around the world... If population poses a problem, it is likely due to distribution, not to growth... There are many wide-open spaces for the population to expand. The trick will be to figure out a way to incentivize responsible growth, not to discourage it entirely.” - Real Clear Science, July 20, 2011

A common green orthodoxy today is that there are too many people on this planet, and that we need to do something about it…Obviously, demographic modeling contains lots of cultural and political assumptions, and should be treated as politically informed rather than neutral observations…It becomes clear that in a sexist, imperialist, capitalist world, it is impossible to separate discussion of population control from hierarchies of oppression. Which population is going to be “controlled” and how will this control come about?... As relatively rich Western countries consume the most energy, it is often argued that it is their populations, in particular, that should be curbed…But to imply that the Earth should come before a child can lead down a dangerous path. It may lead to a resentment of those social groups that migrate or reproduce more often than others. – Shift magazine