Suggested reading
Greenhalgh (1995); Kent and Haub (2005);
Lutz, Sanderson and Scherbov (2004).
density gradient The rate of falling-off in
some value with distance from a central point,
as with the distance-decay relationships
showing land values and population densities
declining away from a city centre (cf.alonso
model;von thu
..
nen model). Such relation-
ships are often associated with patterns of social
contact,diffusionand spatial spread. rj
dependency ratio The number of persons
aged 0–14 and 65 and over, divided by the
number of persons aged 15–64. This total
dependency ratio assesses the dependency
or reliance of one group upon another, and is
one of a suite of measures summarizingage
compositionin a population (see also the
child dependency ratio, or the number of
persons aged 0–14 divided by the number of
persons aged 15–64, and theaged dependency
ratio, or the number of persons aged 65 and
older divided by the number of persons aged
15–64). The assumptions that all persons
under 15 and over 65 are (equally) dependent,
and that all persons within the working ages of
15–64 are (equally) independent are problem-
atic, and are partly based on particular ideas of
work and production incapitalistsocieties.
Other measures reflect broader interest in the
links between generations. For example, the
caretaker ratio divides the number of females
aged 50–64 by the number of persons aged
80 and older, and informs analyses of chan-
ging care relations (Teo, 1996). Overall, these
measures do help expose differences in popu-
lation composition that have profound social
and economic implications, including the
future provision of pensions and social sup-
port, patterns of economic demand and labour
supply, andgenderrelations. (See alsoage-
ing;population pyramid.) ajb
Suggested reading
Shryock and Siegel (1973).
dependency theory A complex body of
theorywith somewhat varied political orien-
tations, presenting versions ofcore–periph-
ery models that purport to explain the
underdevelopmentof countries in the global
southas a consequence of their relationships
with the countries of the global north.
Central to these relationships have been forms
of economic, political and cultural depend-
ence on the products of the global North,
including advanced manufactured goods, polit-
ical models and sociocultural norms.
The earliest major variants of dependency
theory developed inlatin americaand are
especially associated with the Argentinean
structuralist economist Rau ́l Prebisch, for years
the head of the United Nations (UN) Economic
Commission on Latin America (ECLAC) and a
founder of the UN Commission on Trade and
Development (UNCTAD). Prebisch presented
evidence for declining long-term terms of
tradefor global South exporters of agricul-
tural products and raw materials, resulting in
their having to pay relatively more over time
for manufactured imports from the global
North (Kay, 1989, pp. 31–5). This line of
argument, institutionally supported by
ECLAC and UNCTAD, contradicted certain
features of Ricardian, neo-classical trade theory
that argued for the benefits to all countries of
trade based on comparative advantage (see
neo-classical economics). Structuralists thus
legitimized state policies of import-substitution
industrialization (ISI) that had been attempted
in Latin America since the 1930s. The goal of
these ISI policies was to reduce the import of
expensive manufactured goods by producing
such goods domestically under high protective
tariffs.
While Prebisch and other structuralists
quickly recognized the limits of ISI strategies
(Kay, 1989, pp. 36–41), they nonetheless
came under sustained attack from economists
who favoured export-orientedindustrializa-
tionbased oncomparative advantageand
the maintenance of minimal tariff barriers.
At the same time, more politically radical ver-
sions of dependency theory came to the fore
by the 1960s, including the widely read works
of Andre Gunder Frank (1967). Gunder
Frank, influenced in part by the Cuban revo-
lution, argued that only a world-widesocial-
istrevolution – not mere shifts in state trade
policies – could undercut dependency in the
global South and eliminate underdevelop-
ment, which he saw as an inevitable result
ofcore–peripheryrelationships under global
capitalism.
Radical dependency theories gained cur-
rency beyond Latin America in the 1970s,
especially inafrica, but this decade also saw
the formulation of less radical versions of the
dependency thesis, including ‘dependent devel-
opment’ (Evans, 1979) andworld-systems
analysis(Wallerstein, 1979), that more read-
ily allowed for the possibility of some move-
ment upwards from the global periphery.
By the 1980s, however, manydevelopmentGregory / The Dictionary of Human Geography 9781405132879_4_D Final Proof page 154 1.4.2009 3:15pmDENSITY GRADIENT