Human Population Growth Miller Chapter 11-1

Factors affecting population size Populations grow or decline through the interplay of three factors Births Deaths Migration – Immigration – Emigration

Migration Emigration – moving away from a population Begins with “E” like exit Immigration – moving into a population Begins with “I” like into

Population change Population change = (Births + immigration) – (Deaths + emigration) When these balance – ZPG (Zero population growth)

Birth and death rates Calculated as the number of births or deaths per 1000 people in a population in a given year.

Annual percent population change

Fertility Rates Replacement fertility – number of children needed to replace themselves 2.1 to 2.5 per couple.

Replacement Fertility Rates

Total Fertility Rate (TFR) Estimate of average number of children a woman will have between ages Current world value of 2.9 would result in a world population of 296 billion in 150 years

Fertility Rates US US population has increased from 76 million in 1900 to over 276 million. Our fertility rates have dropped since 1950, but we continue to grow very rapidly.

Factors that affect Birth and Fertility rates Importance of children in the workforce Urbanization Cost of raising and educating children Educational and employment opportunities for women Increases Decreases – access to family planning Decreases

Infant mortality rate Average age of marriage or first child Availability of legal abortions Increases with increasing mortality Increases with lower age decreases

Availability of reliable birth control Religious beliefs, traditions, and cultural norms Decreases Increases in countries where large families are encouraged