Answer to Question 1
Developed countries are expected to see a population profile with increasing numbers of older individuals. The profile will look something like an inverted pyramid. Developing countries will become more columnar with increasingly the same number of individuals in each age group.
Answer to Question 2
The population profile for a developed country tends to be fairly columnar. The number of individuals in any particular age group is neither smaller nor larger than the number of individuals in any other age group. In some developed countries the number of individuals in the younger age groups is less than the number of individuals in the older age groups. The fertility rate is low, either below or at replacement.
The population profile for a developing country tends to be pyramidal. The number of individuals in the youngest age groups exceeds, by a large margin, the number of individuals in the oldest age groups. This is partly due to the low life expectancy in the developing countries (fewer people survive to old age, 65+) and partly due to the large number of children born per woman. The fertility rate is at or above replacement. Some developing countries have very high fertility rates (but the rates are lower than they were).
Population predictions for 2000–2050, using three different total fertility rates (
Fertility and Population Density, 1850
Consequences of genetic polymorphisms.
Four consequences of the action of neurotransmitters
Population Growth
Fertility in the Developing World