Geography Reference
In-Depth Information
Population pyramids
Population pyramids provide a graphic means of depicting and comparing the popula-
tions of different countries. In the diagrams below, the vertical axis shows age groups,
while the horizontal axis indicates the percent of a country's population that is in each
of those groups. Most countries have more young people than old people, so the graph
typically has a wide base that tapers upward — rather like the shape of a pyramid. But
the width of the base may vary substantially. Pyramids of developing countries, which
typically have high rates of natural increase and therefore large percentages of their pop-
ulations in the younger age groups, tend to have wide bases. In contrast, the pyramids
of developed countries, with their low rates of natural increase, tend to have narrower
bases.
Population pyramids are particularly useful for contrasting
dependents
and
non-depend-
ents.
These are terms demographers use to characterize people in the under-15 and
65-and-over age groups (
dependents)
and the middle aged people
(non-dependents)
on
whom they must generally rely for their sustenance. Typically, a low percentage of de-
pendents is desirable because it means a high percentage of non-dependents is avail-
able to see to the needs of the young and the old. And in fact, that tends to be the case
in well-off countries. In developing countries, in contrast, a high percentage of depend-
ents relative to non-dependents is the norm. The population pyramids above make these
differences very apparent.
Considering “Overpopulation”
Given the billions who live in poverty, poor health, and crowded conditions, people sometimes sug-
gest that Earth is overpopulated. This controversial subject is made all the more problematical be-
cause it has proven difficult, if not impossible, to define. The clear implication of “overpopulation”
