Diagram which includes stage
The Demographic transition model
(DTM) is a model
used to represent the process of explaining the transformation of
countries from high birth rates
to low birth rates and low
death rates as part of the economic development of a country from a
pre-industrial to an industrialized economy
. It is based on an interpretation
begun in 1929 by the American demographer Warren Thompson
of prior observed changes,
or transitions, in birth and death rates in industrialized
societies over the past two hundred years.
Most developed countries
beyond stage three of the model; the majority of developing countries
are in stage 2 or
stage 3. The model was based on the changes seen in Europe so these
countries follow the DTM relatively well. Many developing countries
have moved into stage 3. The major (relative) exceptions are some poor
countries, mainly in sub-Saharan Africa and some Middle Eastern countries, which are poor or
affected by government policy or civil strife, notably Pakistan, Palestinian
Territories, Yemen and Afghanistan.
Summary of the theory
The transition involves four stages, or possibly five.
- In stage one, pre-industrial
society, death rates and birth rates are high and roughly in
- In stage two, that of a developing country, the death rates drop
rapidly due to improvements in food supply and sanitation, which
increase life spans and reduce disease. These changes usually come
about due to improvements in farming techniques, access to
technology, basic healthcare, and education. Without a
corresponding fall in birth rates this produces an imbalance, and the countries in this stage
experience a large increase in population.
- In stage three, birth rates fall due to access to contraception, increases in wages, urbanization, a reduction in subsistence agriculture, an increase
in the status and education of women, a reduction in the value of
children's work, an increase in parental investment in the
education of children and other social changes. Population growth
begins to level off.
- During stage four there are both low birth rates and low death
rates. Birth rates may drop to well below
replacement level as has happened in countries like Germany, Italy, and
Japan, leading to a shrinking population, a threat to many
industries that rely on population growth. As the large
group born during stage two ages, it creates an economic burden on
the shrinking working population. Death rates may remain
consistently low or increase slightly due to increases in lifestyle
diseases due to low exercise levels and high obesity and an aging population in developed countries.
As with all models, this is an idealized picture of population
change in these countries. The model is a generalization that
applies to these countries as a group and may not accurately
describe all individual cases. The extent to which it applies to
less-developed societies today remains to be seen. Many countries such as
China, Brazil and Thailand have passed through the DTM very quickly due to
fast social and economic change.
particularly African countries, appear to be stalled in the second
stage due to stagnant development and the effect of AIDS
In pre-industrial society, death rates and birth rates were both
high and fluctuated rapidly according to natural events, such as
drought and disease, to produce a relatively constant and young
population. Children contributed to the economy of the household
from an early age by carrying water, firewood, and messages, caring
for younger siblings, sweeping, washing dishes, preparing food, and
doing some work in the fields.
Raising a child cost little more than feeding him; there were no
education or entertainment expenses and, in equatorial Africa,
there were no clothing expenses either. Thus, the total cost of raising children
exceeded their contribution to the household. In addition, as they
became adults they become a major input to the family business,
mainly farming, and were the primary form of insurance for adults
in old age. In India, an adult son was all that prevented a widow
from falling into destitution. While death rates remained high
there was no question as to the need for children, even if the
means to prevent them had existed.
The main means of survival in stage one was through hunting and
gathering food, mainly due to the absence of the Agricultural
World population 10,000 BC - 2000
This stage leads to a fall in death rates and an increase in
population. The changes leading to this stage in Europe were
initiated in the Agricultural Revolution
the 18th century and were initially quite slow. In the 20th
century, the falls in death rates in developing countries tended to
be substantially faster. Countries in this stage include Yemen, Afghanistan, the Palestinian territories, Bhutan and Laos and much of
Sub-Saharan Africa (but do not
include South Africa, Zimbabwe, Botswana, Swaziland, Lesotho, Namibia, Kenya and Ghana, which have
begun to move into stage 3).
The decline in the death rate is due initially to two factors:
- First, improvements in the food supply brought about by higher
yields in agricultural practices and better transportation prevent
death due to starvation and lack of water. Agricultural
improvements included crop rotation,
selective breeding, and seed drill technology.
- Second, significant improvements in public health reduce
mortality, particularly in childhood. These are not so much medical
breakthroughs (Europe passed through stage two before the advances
of the mid-20th century, although there was significant medical
progress in the 19th century, such as the development of vaccination) as they are improvements in water
supply, sewerage, food handling, and
general personal hygiene following from
growing scientific knowledge of the causes of disease and the
improved education and social status of mothers.
A consequence of the decline in mortality in Stage Two is an
increasingly rapid rise in population growth (a "population explosion
") as the gap
between deaths and births grows wider. Note that this growth is not
due to an increase in fertility (or birth rates) but to a decline
in deaths. This change in population occurred in northwestern
Europe during the 19th century due to the Industrial Revolution
. During the
second half of the 20th century less-developed countries entered
Stage Two, creating the worldwide population explosion that has
demographers concerned today.
Another characteristic of Stage Two of the demographic transition
is a change in the age structure
of the population. In Stage One, the majority of deaths are
concentrated in the first 5–10 years of life. Therefore, more than
anything else, the decline in death rates in Stage Two entails the
increasing survival of children and a growing population. Hence,
the age structure of the population becomes increasingly youthful
and more of these children enter the reproductive cycle of their
lives while maintaining the high fertility rates of their parents.
The bottom of the "age pyramid
widens first, accelerating population growth. The age structure of
such a population is illustrated by using an example from the
Stage Three moves the population towards stability through a
decline in the birth rate. There are several factors contributing
to this eventual decline, although some of them remain speculative:
- In rural areas continued decline in childhood death means that
at some point parents realize they need not require so many
children to be born to ensure a comfortable old age. As childhood
death continues to fall and incomes increase parents can become
increasingly confident that fewer children will suffice to help in
family business and care for them in old age.
- Increasing urbanization changes the
traditional values placed upon fertility and the value of children
in rural society. Urban living also raises the cost of dependent
children to a family. A recent theory suggests that urbanization
also contributes to reducing the birth rate because it disrupts
optimal mating patterns. A 2008 study in Iceland found that the
most fecund marriages are between distant cousins. Genetic
incompatibilities inherent in more distant outbreeding makes
- In both rural and urban areas, the cost of children to parents
is exacerbated by the introduction of compulsory education acts and
the increased need to educate children so they can take up a
respected position in society. Children are increasingly prohibited
under law from working outside the household and make an
increasingly limited contribution to the household, as school
children are increasingly exempted from the expectation of making a
significant contribution to domestic work. Even in equatorial
Africa, children now need to be clothed, and may even require
school uniforms. Parents begin to consider it a duty to buy
children books and toys. Partly due to education and access to
family planning, people begin to reassess their need for children
and their ability to raise them.
A major factor in reducing birth rates in stage 3
countries such as Malaysia is the availability of family planning
facilities, like this one in Kuala Terenganu, Terenganu,
- Increasing female literacy and employment lower the uncritical
acceptance of childbearing and motherhood as measures of the status
of women. Working women have less time to raise
children; this is particularly an issue where fathers traditionally
make little or no contribution to child-raising, such as southern Europe or Japan.
Valuation of women beyond childbearing and motherhood becomes
- Improvements in contraceptive technology are now a major
factor. Fertility decline is caused as much by changes in values
about children and sex as by the availability of contraceptives and
knowledge of how to use them.
The resulting changes in the age structure of the population
include a reduction in the youth dependency ratio
and eventually population aging
. The population structure
becomes less triangular and more like an elongated balloon. During
the period between the decline in youth dependency and rise in old
age dependency there is a demographic
of opportunity that can potentially produce economic
growth through an increase in the ratio of working age to dependent
population; the demographic
However, unless factors such as those listed above are allowed to
work, a society's birth rates may not drop to a low level in due
time, which means that the society cannot proceed to Stage Four and
is locked in what is called a demographic trap
that have experienced a fertility decline of over 40% from their
pre-transition levels include: Costa Rica, El
Salvador, Panama, Jamaica, Mexico, Colombia, Ecuador, Guyana, Surinam, Philippines, Indonesia, Malaysia, Sri
Lanka, Turkey, Azerbaijan, Turkmenistan, Uzbekistan, Egypt, Tunisia, Algeria, Morocco, Lebanon, South Africa, India, Saudi Arabia, and many Pacific
that have experienced a fertility decline of 25-40% include:
Honduras, Guatemala, Nicaragua, Paraguay, Bolivia, Vietnam, Myanmar, Bangladesh, Tajikistan, Jordan, Qatar, Albania, United Arab
Emirates, Zimbabwe, and Botswana.
that have experienced a fertility decline of 10-25% include:
Haiti, Papua New
Guinea, Nepal, Pakistan, Syria, Iraq, Libya, Sudan, Kenya, Ghana and Senegal.
This occurs where birth and death rates are both low. Therefore the
total population is high and stable. Some theorists consider there
are only 4 stages and that the population of a country will remain
at this level. The DTM is only a suggestion about the future
population levels of a country. It is not a prediction.
that are at this stage (Total
Fertility Rate of less than 2.5 in 1997) include: United States, Canada, Argentina, Australia, New Zealand, most of Europe, Bahamas, Puerto Rico, Trinidad and Tobago, Brazil, Sri Lanka, South
Korea, Singapore, Iran, China, Turkey, North Korea, Thailand and Mauritius.
[[Image:World population (UN).svg|thumb|right|300px|United Nation's
population projections by location.
Note the vertical axis is logarithmic
& is millions of people.]]The original Demographic Transition
model has just four stages; however, some theorists consider that a
fifth stage is needed to represent countries that have sub-replacement fertility
European and many East Asian countries now have higher death rates
than birth rates.
There may be a further stage of demographic development. In an
article in the August 2009 issue of Nature
Kohler and Billari show that previously negative relationship
between national wealth (as measured by the human development index
birth rates has become J-shaped. Development promotes fertility
decline at low and medium HDI levels, but advanced HDI promotes a
rebound in fertility. In many countries with very high levels of
development (around 0.95) fertility rates are now approaching two
children per woman - although there are exceptions, notably
Effects on age structure
The decline in death rate and birth rate that occurs during the
demographic transition leads to a radical transformation of the age
structure. When the death rate declines during the second stage of
the transition, the result is primarily an increase in the child
population. The reason is that when the death rate is high (stage
one), the infant mortality rate is very high, often above 200
deaths per 1000 children born. When the death rate falls or
improves, this, in general, results in a significantly lower infant
mortality rate and, hence, increased child survival. Over time, as
cohorts increased by higher survival rates get older, there will
also be an increase in the number of older children, teenagers, and
young adults. This implies that there is an increase in the fertile
population which, with constant fertility rates, will lead to an
increase in the number of children born. This will further increase
the growth of the child population. The second stage of the
demographic transition, therefore, implies a rise in child
It has to be remembered that the DTM is only a model and cannot
necessarily predict the future. It does however give an indication
of what the future birth and death rates may be for a country,
together with the total population size. There are therefore
limitations to it as with any model. Most particularly, of course,
the DTM makes no comment on change in population due to
Non-applicability to less-developed countries
DTM has a questionable applicability to less economically
(LEDCs), where wealth and information
access are limited. For example, the DTM has been validated
primarily in Europe, Japan and North America where demographic data
exists over centuries, whereas high quality demographic data for
most LDCs did not become widely available until the mid 20th
century. DTM does not account for recent phenomena such as AIDS
; in these areas HIV has become the leading source
of mortality. Some trends in waterborne bacterial infant
mortality are also disturbing in countries like Malawi, Sudan and
Nigeria; for example, progress in the DTM clearly arrested
and reversed between 1975 and 2005.
Generalization from European experience
The DTM is mostly applicable for European countries in general. It
also contained an hypothesis that other countries would follow
suit. The DTM assumes that countries will go through all the
stages. Some countries may even skip stages. Demographic data for
lesser developed countries span about five decades, leading to
questionable extrapolation of the experiences of the most developed
Economic development not sufficient cause to effect demographic
DTM assumes that population changes are induced by industrial
changes and increased wealth, without taking into account the role
of social change in determining birth rates, e.g., the education of
women. In recent decades more work has been done on developing the
social mechanisms behind it.
DTM assumes that the birth rate is independent of the death rate.
Nevertheless, demographers maintain that there is no historical
evidence for society-wide fertility rates rising significantly
after high mortality events. Notably, some historic populations
have taken many years to replace lives such as the Black Death
Some have claimed that DTM does not explain the early fertility
declines in much of Asia in the second half of the 20th century or
the delays in fertility decline in parts of the Middle East.
Nevertheless, the demographer John C Caldwell has suggested
that the reason for the rapid decline in fertility in some developing countries compared to Western Europe, the United States, Canada, Australia and New Zealand is mainly due to government programs and a massive
investment in education both by governments and
Application to the U.S. in the 19th and 20th centuries
A simplification of the DTM theory proposes an initial decline in
mortality followed by a later drop in fertility. The changing
demographics of the U.S. in the last two centuries did not parallel
this model. Beginning around 1800, there was a sharp fertility
decline; at this time, an average woman usually produced seven
births per lifetime, but by 1900 this number had dropped to nearly
four. A mortality decline was not observed in the U.S. until almost
1900—a hundred years following the drop in fertility. Today, the
U.S. is recognized as having both low fertility and mortality
rates. Specifically, birth rates stand at 14 per 1000 per year and
death rates at 8 per 1000 per year.
- Carrying capacity
- Caldwell, John C.
1976. "Toward a restatement of demographic transition theory."
Population and Development Review 2:321-366.
- Coale, Ansley J. 1973. "The
demographic transition," IUSSP Liege International Population
Conference. Liege: IUSSP. Volume 1: 53-72.
- Coale, Ansley J., Barbara A.
Anderson, and Erna Härm. 1979. Human Fertility in Russia since
the Nineteenth Century. Princeton, NJ: Princeton University
- Coale, Ansley J. and Susan C.
Watkins, Eds. 1987. The Decline of Fertility in Europe.
Princeton, N.J.: Princeton University Press.
- Davis, Kingsley. 1963. "The
theory of change and response in modern demographic history."
Population Index 29(October): 345-366.
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Review of Sociology 20: 203-233.
- (Note: Click "Publications," then click on title.)
- Landry, Adolphe, 1982 , La révolution démographique -
Études et essais sur les problèmes de la population, Paris,
INED-Presses Universitaires de France
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- Notestein, Frank W. 1945.
"Population — The Long View," in Theodore W. Schultz, Ed., Food
for the World. Chicago: University of Chicago Press.
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Sociology 34(6): 959-975. After the next World War, we will
see Germany lose more women and children and soon start again from
a developing stage.
- Barcelona fieldwork
- Caldwell (2006), Chapter 5
- BBC bitesize
- Caldwell (2006), Chapter 10
- Marathon geography
- "Kissing cousins, missing children". The Economist 7
- Main vision
- Myrskyla, M., Kohler, H-P., and Billari, F.
Advances in development reverse fertility declines.
Nature 460, 741-743 (6 August 2009).
- "The best of all possible worlds?" The Economist 6
- Ronald Lee, The Demographic Transition: Three
- Nigeria: Reversal of Demographic
- World factbook