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1 Review Describe the general trends of human population growth over time 2 Review why do populations in different countries grow at different rates Form an Opinion Are age structures diagrams useful in predicting future population trends 3 Visual Thinking Describe the changes in human population predicted by the graph on pg 119. How do you think those changes will affect society.

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CH 5 POPULATIONS 5.3 Human Population Growth

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How quickly is the global human population growing Worldwide, there are more than four human births every second What does human population growth mean for us and our interactions with the rest of the biosphere.

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Historical Overview Population grew very slowly Food shortages High predation and diseases Harsh life Very high birth rate.

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Exponential Human Population Growth Improved nutrition, sanitation, medicine, and healthcare, dramatically reduced death rates, industrial revolution Easier life Birth rates stayed high.

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Thomas Malthus Thought that human populations would be regulated by competition (war), limiting resources (famine), parasitism (disease), and other density-dependent factors Thought human growth rate would grow faster than the increase of food production.

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Exponential growth continued up to the second half of the twentieth century, reaching a peak around 19621963, and then it began to drop Still increasing but at a lower rate.

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Patterns of Human Population Growth Affected by social and economic factors Birthrates, death rates, and the age structure of a population play a role Demography Scientific study of human populations Demographic transition Dramatic change from high birthrates and death rates to low birthrates and death rates.

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Demographic Transition Stage 1 Birthrates and death rates are high.

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Demographic Transition Stage 2 Advances in nutrition, sanitation, and medicine lead to lower death rates.

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Demographic Transition Stage 3 Higher level of education and living standards, families have fewer children and the birthrate falls.

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Age Structure and Population Growth

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Future Population Growth Project 9 BILLION by 2050.