# Class Notes 7: Human Population "Go Forth And Multiply!" That's what the human population has successfully been doing for thousands and thousands of years,

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Class Notes 7: Human Population "Go Forth And Multiply!" That's what the human population has successfully been doing for thousands and thousands of years, expanding, exploring, migrating, conquering, utilizing, evolving, civilizing, industrializing, and now, destroying the very land upon which we live.

I. World Population (A) In the U.S., a census is taken every 10 yrs. 1.Includes how many people, economic condition, and where they live. (B) Demography the study of human population size, density and distribution, movement, and its birth and death rate. (C) What factors affect growth of human population? Eradicated diseases Increase food supply Infant mortality rate decrease Clean Water * people live longer->reproduce more=population grows

II. Calculating Growth Rate (A)There are a number of factors that determine population growth rate. 1.Birthrate is the number of live births per 1000 population in a given year. 2.Death rate is the number of deaths per 1000 population in a given year. (birthrate + immigration) – (death rate + emigration) = Population Growth Rate (PGR)

Growth Rate & Population

III. Doubling Time (A)Doubling Time is the time needed for a population to double in size. 1.Depends on the current population and growth rate a.Fast growth rate = fast doubling time b.Slow or negative growth rate = slow doubling time

IV. Age Structure (A) Age structure refers to the proportions of the population that are in different age levels. Graph is an example of the age distributions in China

Summary What factors influence human population? Is the population of humans on earth still growing? What do you think will happen if it doesn’t stop growing?

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