9-1 studying human populations page 219. a. the human population over time 1. demography is the...

9-1 Studying Human Populations

Page 219

A. The Human Population Over Time

• 1. Demography is the study of populations.

A. The Human Population Over Time• 2. Industrial and scientific revolutions caused a

period of exponential growth.

A. The Human Population Over Time

• 3. Scientists believe we can not indefinitely sustain the current population at today's standards of living.

B. Forecasting Population Size• 1. Demographers make predictions based on

age structure (distribution of ages in a specific population at a certain time).

B. Forecasting Population Size• 2. Survivorship is the percentage of members

of a group that are likely to survive to a given age.

B. Forecasting Population Size

• 3. Survivorship curves show 3 possible outcomes:– Type I: Population where most individuals live to

an advanced age.– Type II: Population where all ages have a similar

death rate.– Type III: Population where many offspring die.

B. Forecasting Population Size• 4. Fertility Rates are the average amount of

children a woman gives birth to in her lifetime.

B. Forecasting Population Size• 5. Migration is the movement from one area

to another.

C. Declining Death Rates

• 1. Life expectancy is the average # of years members of a population are likely to live.

C. Declining Death Rates

• 2. The average life expectancy has increased to more than 67 yrs. Worldwide! 80 yrs. In some developed countries!

D. The Demographic Transition

• 1. Model that describes how economic and social changes affect population growth rates.

D. The Demographic Transition

• 2. Four Stages:– Pre-industrial– Transitional– Industrial– Post-Industrial