How has size of human population changed over time? Why do population growth rates differ in countries throughout the world?

Back in the day….. opopulations grew slowly ofood scarce oincurable diseases oOnly ½ of children survived to adulthood oFamilies had many children Then……. oHuman population grew rapidly oImprovements in agriculture, medicine, sanitation, and technology reduced death rates. oHuman population grew exponentially

Demography- study of human populations by examining characteristics of human populations and attempting to explain how those populations change over time. Reasons why some countries have high/low growth rates: 1.Birthrates 2.Death rates 3.Age structure of a population

Age structure diagrams- (or population profiles) model which graphs the numbers of people in different age groups in population. Used to predict future growth

Demographic transition-dramatic change in birth/death rates Steps of demographic transition: Throughout most of history: high birthrates and high death rates As countries begin to modernize: lower death rate, population grows and begin demographic transition More modernizing: families have fewer children (birthrate falls), population growth slows Demographic transition complete: when birthrate falls to meet death rate and population growth stops