DEMOGRAPHIC TRANSITIONdiseases such as malaria. Even relatively weak na-
tional governments have instituted major improve-
ments in health conditions, although often only
with the help of international agencies.
Nevertheless, mortality levels are still higher
than those in many rich societies due to such
factors as inadequate diets and living conditions,
and inadequate development of health facilities
such as hospitals and clinics. Preston (1976) ob-
serves that among non-Western lesser-developed
countries, mortality from diarrheal diseases (e.g.,
cholera) has persisted despite control over other
forms of infectious disease due to the close rela-
tionship between diarrheal diseases, poverty, and
ignorance—and therefore a nation’s level of so-
cioeconomic development.
Scholars (Caldwell 1986; Palloni 1981) have
warned that prospects for future success against
high mortality may be tightly tied to aspects of
social organization that are independent of simple
measures of economic well-being: Governments
may be more or less responsive to popular need
for improved health; school system development
may be important for educating citizens on how to
care for themselves and their families; the equita-
ble treatment of women may enhance life expect-
ancy for the total population.
Recent worldwide mortality trends may be
charted with the help of data on life expectancy at
age zero that have been gathered, sometimes on
the basis of estimates, by the Population Reference
Bureau (PRB), a highly respected chronicler of
world vital rates. For 165 countries with relatively
stable borders over time, it is possible to relate
estimated life expectancy in 1986 with the same
figure for 1998. Of these countries, only 13.3
percent showed a decline in life expectancy during
the time period. Some 80.0 percent had overall
increasing life expectancy, but the gains were high-
ly variable. Of all the countries, 29.7 percent actu-
ally had gains of at least five years or more, a
sizable change given historical patterns of mortality.
An indication of the nature of change may be
discerned by looking at Figure 1, which shows a
graph of the life expectancy values for the 165
countries with stable borders. Each point repre-
sents a country and shows the level of life expect-
ancy in 1986 and in 1998. Note the relatively high
levels of life expectancy by historical standards for
most countries in both years. Not surprisingly,
there is a strong tendency for life expectancy
values to be correlated over time. A regression
straight line, indicating average life expectancy in
1998 as a function of life expectancy in 1986
describes this relationship. As suggested above,
the levels of life expectancy in 1998 tend to be
slightly higher than the life expectancy in 1986.
Since geography is highly associated with econom-
ic development, the points on the graph generally
form a continuum from low to high life expectan-
cy. African countries tend to have the lowest life
expectancies, followed by Asia, Oceania, and the
Americas. Europe has the highest life expectancies.The African countries comprise virtually all
the countries with declining life expectancies, prob-
ably a consequence of their struggles with ac-
quired immune deficiency syndrome (AIDS), mal-
nutrition, and civil disorder. Many of them have
lost several years of life expectancy in a very short
period of time. However, a number of the African
countries also have sizeable increases in life
expectancies.Asian and American countries dominate the
mid-levels of life expectancy, with the Asian coun-
tries showing a strong tendency to increase their
life expectancies, consistent with high rates of
economic development.Unfortunately, Figure 1 does not include the
republics of the former Soviet Union, since exactly
comparable data are not available for both time
points. Nevertheless, there is some consensus
among experts that life expectancy has deteriorat-
ed in countries such as Russia that have made the
transition from communism to economically-un-
stable capitalism.WHAT DRIVES FERTILITY RATES?The analysis of fertility decline is somewhat more
complicated analytically than mortality decline.
One may presume that societies will try, if given
resources and a choice, to minimize mortality
levels, but it seems less necessarily so that societies
have an inherent orientation toward low fertility,
or, for that matter, any specific fertility level. In
addition, fertility rates may vary quite widely across