Biological Reasons for Population Growth

Biological Reasons for Population Growth

The study of human populations, their characteristics, and what happens to them is
known as demography. Demographers can predict the future growth of a population by
looking at several different biological indicators. When we look at birth rates and death rates in various countries of the world, in almost all cases the birth rate exceeds the death rate. Therefore, the size of the population must increase. Some countries that have high birth rates and high death rates, with birth rates greatly exceeding the death rates, will grow rapidly (Afghanistan and Ethiopia). Such countries Usually have an extremely high mortality rate among children because of disease and malnutrition. Some countries have high birth rates and low death rates and will grow extremely rapidly ~Guatemala and Syria). Infant mortality rates are moderately high in these countries. Other countries have low birth rates and death rates that closely match the birth rates and will grow slowly (Sweden and the United Kingdom). These and other more, developed countries typically have very low infant mortality rates. Obviously, the most important determinant of the rate at which human populations grow is related to the number of women in the population who are having children and the number each will have. The total fertility rate of a population is the number of children born per woman per lifetime. A total fertility rate of 2.1 is known as replacement fertility, since in the long run, if the total fertility rate is 2.1, population growth will stabilize. When population is not growing and the number of births equals the number of deaths, it is said to exhibit zero population growth. The age structure of a population also has a great deal to do with the rate of population growth. If a population has a large number of young people who are in the process of raising families or who will be raising families in the near future, the population will continue to increase even if the families limit themselves to two children.