1. Slide 1 of 24 Copyright Pearson Prentice Hall 5-3 Human Population Growth

2. Slide 2 of 24 Copyright Pearson Prentice Hall Historical Overview Like the populations of many other living organisms, the size of the human population tends to increase with time. For most of human existence, the population grew slowly. Limiting factors kept population sizes low.

3. 5-3 Human Population Growth Slide 3 of 24 Copyright Pearson Prentice Hall Historical Overview About 500 years ago, the human population began growing more rapidly. Life was made easier and safer by advances in agriculture and industry. Death rates were dramatically reduced due to improved sanitation, medicine, and healthcare, while birthrates remained high.

4. 5-3 Human Population Growth Slide 4 of 24 Copyright Pearson Prentice Hall Historical Overview With these advances, the human population experienced exponential growth. Human Population Growth

5. 5-3 Human Population Growth Slide 5 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth The scientific study of human populations is called demography. Demography examines the characteristics of human populations and attempts to explain how those populations will change over time.

6. 5-3 Human Population Growth Slide 6 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth Birthrates, death rates, and the age structure of a population help predict why some countries have high growth rates while other countries grow more slowly.

7. 5-3 Human Population Growth Slide 7 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth The Demographic Transition Over the past century, population growth in the United States, Japan, and much of Europe has slowed dramatically. According to demographers, these countries have completed the demographic transition, a dramatic change in birth and death rates.

8. 5-3 Human Population Growth Slide 8 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth The demographic transition has three stages. In stage 1, there are high death rates and high birthrates. In stage 2, the death rate drops, while the birthrate remains high. The population increases rapidly. In stage 3, the birthrate decreases, causing population growth to slow.

9. 5-3 Human Population Growth Slide 9 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth The demographic transition is complete when the birthrate falls to meet the death rate, and population growth stops.

10. 5-3 Human Population Growth Slide 10 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth Age Structure Population growth depends, in part, on how many people of different ages make up a given population. Demographers can predict future growth using models called age-structure diagrams. Age-structure diagrams show the population of a country broken down by gender and age group.

11. 5-3 Human Population Growth Slide 11 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth In the United States, there are nearly equal numbers of people in each age group. This age structure diagram predicts a slow but steady growth rate for the near future. Males Females 8 6 4 2 0 2 4 6 8 Percentage of Population 80+ 60–64 20–24 0–4 40–44 Age (years) U.S. Population

12. 5-3 Human Population Growth Slide 12 of 24 Copyright Pearson Prentice Hall Patterns of Population Growth In Rwanda, there are many more young children than teenagers, and many more teenagers than adults. This age structure diagram predicts a population that will double in about 30 years. 80+ 60–64 20–24 0–4 Age (years) Males Females Rwandan Population 40–44 Percentage of Population

13. 5-3 Human Population Growth Slide 13 of 24 Copyright Pearson Prentice Hall Future Population Growth To predict human population growth, demographers must consider the age structure of each country, as well as the prevalence of life- threatening diseases. If growing countries move toward the demographic transition, growth rate may level off or decrease.

14. 5-3 Human Population Growth Slide 14 of 24 Copyright Pearson Prentice Hall Future Population Growth

15. 5-3 Human Population Growth Slide 15 of 24 Copyright Pearson Prentice Hall Future Population Growth Ecologists suggest that if growth does not slow down, there could be serious damage to the environment and global economy.serious damage to the environment and global economy Economists assert that science, technology, and changes in society may control the negative impact of population growth.science, technology, and changes in society

16. 5-3 Human Population Growth Slide 16 of 24 A survivorship curve is a graph showing the number or proportion of individuals surviving at each age for a given species or group (e.g. males/females).the number or proportion of individuals surviving at each age for a given species or group Survivorship curves can be constructed for a given cohort (a group of individuals of roughly the same age) based on a life table. cohort Survivorship curves tell us something about how long individuals survive in a population. There are basically three types of survivorship curves:how long individuals survive in a population

17. 5-3 Human Population Growth Slide 17 of 24 Type I survivorship curves are for species that have a high survival rate of the young, live out most of their expected life span and die in old age. Ex. Human Type II survivorship curves are for species that have a relatively constant death rate throughout their life span. Death could be due to hunting or diseases. relatively constant death rate throughout their life span. Death could be due to hunting or diseases. Ex. coral, squirrels, honey bees, birds, and many reptiles. Type III survivorship curves are found in species that have many young, most of which die very early in their life.have many young, most of which die very early in their life Ex. Plants, oysters and sea urchins

18. 5-3 Human Population Growth Slide 18 of 24