In countries where there are high birth rates their are also high death rates. People have many children so that a few may survive
Demographic economics or population economics is the application of economic analysis to demography, the study of human populations, including size, growth, density, distribution, and vital statistics.
Aspects of the subject include
Human geography is one of the two major sub-fields of the discipline of geography. Human geography is a branch of the social sciences that studies the world, its people, communities and cultures with an emphasis on relations of and across space and place. Human geography differs from physical geography mainly in that it has a greater focus on studying human activities and is more receptive to qualitative research methodologies. As a discipline, human geography is particularly diverse with respect to its methods and theoretical approaches to study.
Geographical knowledge, both physical and social, has a long history. In the history of geography, geographers have often recorded and described features of the Earth that might now be considered the remit of human, rather than physical, geographers. For example Hecataeus of Miletus, a geographer and historian in ancient Greece, described inhabitants of the ancient world as well as physical features.
The birth rate is the total number of births per 1000 of a population each year. The rate of births in a population is calculated in several ways: live births from a universal registration system for births, deaths, and marriages; population counts from a census, and estimation through specialized demographic techniques. The birth rate (along with mortality and migration rate) are used to calculate population growth.
The crude birth rate is the number of births per 1,000 people per year. Another term used interchangeably with birth rate is natality. When the crude death rate is subtracted from the crude birth rate, the result is the rate of natural increase (RNI). This is equal to the rate of population change (excluding migration).
According to the Encyclopedia of International Development, the term demographic trap is used by demographers "to describe the combination of high fertility (birth rates) and declining mortality (death rates) in developing countries, resulting in a period of high population growth rate (PGR)." High fertility combined with declining mortality happens when a developing country moves through the demographic transition of becoming developed.
During "stage 2" of the demographic transition, quality of health care improves and death rates fall, but birth rates still remain high, resulting in a period of high population growth. The term "demographic trap" is used by some demographers to describe a situation where stage 2 persists because "falling living standards reinforce the prevailing high fertility, which in turn reinforces the decline in living standards." This results in more poverty, where people rely on more children to provide them with economic security. Social scientist John Avery explains that this results because the high birth rates and low death rates "lead to population growth so rapid that the development that could have slowed population is impossible."
Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation being less populous than the previous one in a given area. In developed countries sub-replacement fertility is any rate below approximately 2.1 children born per woman, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement was 2.33 children per woman in 2003. This can be "translated" as 2 children per woman to replace the parents, plus a "third of a child" to make up for the higher probability of boys being born, and early mortality prior to the end of their fertile life.
Replacement level fertility in terms of the net reproduction rate (NRR) is exactly one, because the NRR takes both mortality rates and sex ratios at birth into account.