Human Population Growth History of Human Population Growth

Human Population Growth

History of Human Population Growth l The populations of humans on the planet Earth has grown exponentially over time.

History of Human Population Growth l The human population began growing exponentially 500 years ago. l The Industrial Revolution increased the amount of food available. l Advances in public health decreased the death rate.

The Demographic Transition l Describes a dramatic shift in birth and death rates in different countries. l It has four stages. l Different countries can be in different stages. l Ex: USA – Stage 4, Mexico – Stage 3, Uganda – Stage 2.

Demographic Transition Graph

Stage One: l High birth rates; high death rates. l Population remains constant.

Stage Two: l Advances in health care decrease death rate; birth rate is still high. l Population increases.

Stage Three: l Death rate is low; birth rate decreasesmore education l Population growth slows

Stage Four l Death rates are low; birth rates are low. l Population is steady.

Age Structure l Models the age distribution of a population in a country. l Males are on the left; females are on the right. l There are three different types of structures commonly seen.

Expanding Population Pyramid The largest group is children who will have babies within 20 years l Population of this country is growing rapidly. l • Needs: Schools, hospitals, jobs

Stable Population Pyramid Each group is roughly the same size. l Population is remaining the same. l Needs: jobs, child care, elder care l

Declining Population Pyramid The largest group is older adults who will be unable to work within 30 years. l Few children to replace those l. Needs: Elder care; workers in 30 years. finding workers to support economy l