The themes of scale, pattern, place, and interdependence can all be illustrated with population topics. For example,
we may analyze the distribution of the human population at different scales: global, continental, national, state or province,
and local community. Explanations of why population is growing or declining in some places and not others center on understanding
the processes of fertility, mortality, and migration. In stressing the relevance of place context for example, we may assess
why fertility rates have dropped in some parts of the developing world but not others, and how age—sex structures vary
from one country to another.
Analysis of refugee flows, immigration, internal migration,
and residential mobility helps us appreciate the interconnections between population phenomena and other topics. Environmental
degradation may prompt rapid out-migration and urbanization, in turn creating new pressures on the environment. Refugee flows
may be magnified when groups have no access to political power because of the way boundaries have been drawn. Rapid immigration
to certain parts of the world fosters regional differences in industrial employment and political sentiment toward foreigners.
This also aids in our understanding of contemporary growth
trends by considering how models of population change, including the demographic and epidemiological (mortality) transitions.
Given these kinds of understandings, we are in a position to evaluate the role, strengths, and weaknesses of major population
policies. For example, how might increasing the education levels of females lead to lower fertility?