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Trends in Human Population Growth
The graph in
Figure 12
on the last page is somewhat deceptive. Population trends can
be altered by events such as disease and war.
Figure 13
(next page) shows a few histori-
cal events that have changed population trends.
Figure 12
could also easily be misinter-
preted because human population growth is not the same in all countries. However,
population growth trends are often similar in countries that have similar economies.
For example, one trend that has developed during the previous century is a change in
the population growth rate in industrially developed countries such as the United
States. An industrially developed country is advanced in industrial and technological
capabilities and has a population with a high standard of living. Criteria for determining
developed countries include average national income, individual average health and
education, and national export and import of goods.
In its early history, the United States had a high birthrate and a high death rate. It was
not uncommon for people to have large families and for individuals to die by their early
forties. Many children also died before reaching adulthood. Presently, the birthrate in
the United States has decreased dramatically and the life expectancy is greater than
seventy years. This change in a population from high birth and death rates to low birth
and death rates is called a
demographic transition.
Connection
MATH
How do population growth rates (PGR) compare in industrially
developed countries and developing countries? As an example, we will compare the
2008 populations for the United States and Honduras, a small country in Central
America. The calculation for PGR is
birthrate
-
death rate
+
migration rate
______________________________
10
=
PGR (%)
In our example, we’ll have to divide the final answer by 10 to get a percentage because
the rates are calculated per 1000. The United States has birthrate 14.1 (per 1000), death
rate 8.3 (per 1000), and migration rate 2.9 (per 1000). This gives a PGR of 0.87 percent
for the United States. Honduras has birthrate 26.9 (per 1000), death rate 5.4 (per 1000),
and migration rate -1.3 (per 1000). This gives a PGR of 2.02 percent for Honduras.
Get It?
Compare
the population growth rates in the United States and the United Kingdom,
which has a birthrate of 12 (per 1000), death rate 8.8 (per 1000), and migration rate
2.5 (per 1000).
WORD ORIGINS
demography
demo–
from the Greek word
demos
; meaning
people
–ography
from the French word
graphie
; meaning
writing
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Module 4 • Population Ecology