Human Populations
Demography Demography is the study of populations especialy refers to the human pop. Demographers look at historical size and make up of populations in different countries to make comparisons and predictions
Types of Countries Countries are in one of two categories: Developed countries- higher incomes, slower pop. Growth, and diverse industrial economics Developing countries- lower average incomes, simple and agriculture-based economics, and rapid pop. growth
Types of Countries Developed countries slow pop growth? Low infant mortality Less need for large families More focus on careers Women have more freedom
Types of Countries Developing countries rapid pop growth? high infant mortality greater need for large families Less freedom for women Cultural Traditions Male child preference
Human Populations
Population Over Time Population grew exponentially during the 1800’s Food production was up and hygiene improved, this came with the industrial and scientific revolution Earth most likely cannot continue to support this growth
Forecasting Population Size Demographers use the following characteristics to predict population changes Age Structure Survivorship Fertility Rates Migration patterns
Age Structure Age structure: the distribution of ages in a specific population at a certain time Countries with high growth rate have more young people than older people Countries with slow or no growth rate have an even distribution of ages Graphed using a population pyramid A double-sided bar graph
Population Pyramid
Population Pyramid
Population Pyramid
Population Pyramid
Survivorship Survivorship: the percentage of members of a group that survive to any given age Wealthy countries have a type 1 survivorship curve (most people live to be pretty old) Poor countries have a type 3 survivorship curve (many children die)
Survivorship Curves
Survivorship Curves
Fertility Rates A fertility rate is the number of births (usually per year) per 1,000 women of childbearing age (usually 15 to 44). Replacement level is the average number of children each parent must have in order to “replace” themselves. This number is slightly more than 2 because not all children born will survive and reproduce.
Fertility Rates
Demographic Transition The demographic transition is the general pattern of demographic change from high birth and death rates to low birth and death rates, and observed in the history of more-developed countries. The idea is that industrial development causes economic and social progress that then affects population growth rates.
Four Stages of Demographic Transition 1st - A society is in a preindustrial condition, birth rate and the death rate are both at high levels and the population size is stable. 2nd - A population explosion occurs, death rates decline as hygiene, nutrition, and education improve. But, birth rates remain high, so the population grows very fast. 3rd - Population growth slows because birth rate decreases. As the birth rate becomes close to the death rate, the population size stabilizes. 4th - The birth rate drops below replacement level, so the size of the population begins to decrease.
Demographic Transition
Women & Fertility For women increase in education + economic independence = decline in birth rates They are able to take better care of their children Higher survival rates so they do not need to have as many children Contribute to the family by working Fertility rates developed countries ~1.6 children developing countries ~3.6 children