A Changing Human Population

1
A Changing Human Population

• Environmental Science

2
Studying Human Populations

• Demography the study of the characteristics of
  populations (usually human populations)
• Countries are divided into 2 categories by
  demographers
• Developed higher average incomes, slower
  population growth, diverse industrial economies
• Developing lower average incomes, rapid
  population growth, agriculture-based economy

3
Forecasting Population Size

• Demographers try to predict what will happen to a
  population in order to plan for future
  infrastructure and services
• Demographers look at several different factors to
  make their predictions

4
Age Structure

• Age structure describes the distribution of ages
  of a population
• Countries with high growth rates have more young
  people than old people
• Countries with slow growth or no growth have an
  even distribution of ages in the population

5
Survivorship

• The percentage of members of a group that are
  likely to survive to a given age
• To predict survivorship, demographers study a
  group of people born at the same time and notes
  when each member of the group dies.

Age
6
Fertility Rates

• The number a babies born each year per 1000 women
  of childbearing age (15-44)
• Replacement level the average number of
  children parents must have to replace
  themselves

7
Declining Death Rates

• Increased access to food, clean water, and safe
  sewage disposal have lead to a decrease in the
  world death rate
• This decrease has more to do with the huge
  increase in the human population than the birth
  rate.

8
Migration

• Migration in general, is any movement of
  individuals or populations from one location to
  another.
• The populations of many developed countries might
  be decreasing if not for immigration.

9
Declining Death Rates

• The dramatic increase in Earths human population
  in the last 200 years has happened because death
  rates have declined more rapidly than birth
  rates.
• Death rates have declined mainly because more
  people have access to adequate food, clean water,
  safe sewage disposal, medicine/health care.
• The discovery of vaccines in the 20th century
  also contributed to the declining death rates.

10
Life Expectancy

• The average number of years that a member of a
  population is likely to live
• Infant mortality rates have the largest influence
  on life expectancy numbers
• Better medical care has lead to higher life
  expectancy in developed and developing nations.

11
Demographic Transition

• The demographic transition is the general pattern
  of demographic change from high birth and death
  rates to low birth and death rates.
• Industrial development causes economic and social
  progress that then affects population growth
  rates.

12
Women and Fertility

• A decline in birth rates can most clearly be
  related to increasing education and economic
  independence for women (jobs).
• Educated women learn family planning techniques
  and find that they do not need to bear as many
  children to ensure that some will survive.
• Women are able to increase the prosperity for
  their families while spending less energy bearing
  and caring for children.
• Educated women delay child bearing.