2. Human Population
•For most of history, the human population grew slowly
•But for the past 200 years, the human population has grown rapidly.
•3 major factors account for this population increase:
3. Factors
•Humans developed the ability to expand into almost all of the planet’s
climate zones and habitats
•The emergence of early and modern agriculture
• This allowed humans to grow more food for each unit of land area farmed
•Death rates dropped sharply because of improved sanitation and health
care
4. Human Population
•Most of the increase in the world’s population during the last 100 years
took place because of a sharp drop in death rates
• Not a sharp rise in birth rates
•10,000 years ago - when agriculture began, there were roughly 5M
humans in the planet
•By 2012, there are roughly 7B people in the planet
•By 2050, the humab population is projected at 9.5B
5. Human Population
•The rate of population growth has slowed, but the world’s population is
still growing exponentially at a rate of about 1.21% a year
•Meaning, about 83M people were added to the world’s population in 2010
or an average of more than 227,000 people each day
6. Human Population
•Geographically, this growth is unevenly distributed and this pattern is
expected to continue
•About 1% of the 83M new arrivals on the planet were added to the
world’s more developed countries
•The other 99% were added to the world’s less developed countries
7. Human Population
•Human populations grow or decline in particular countries, cities or other
areas through the interplay of 3 factors:
• Births (Fertility)
• Deaths (Mortality)
• Migration
8. Fertility or Birth Rate
•Fertility rate is the no. of children born to a woman during her lifetime.
•Two types of fertility rates affect a country’s pop. size and growth rate:
• 1. Replacement-level fertility rate (RLF)
• 2. Total fertility rate (TFR)
9. Replacement-level fertility rate (RLF)
•The average number of children that couples in a population must bear to
replace themselves
•Reaching RLF will not bring an immediate halt to population growth
because so many future parents are alive
10. Replacement-level fertility rate (RLF)
•If each of today’s couples had an average of 2.1 children, they would not
be contributing to population growth
•But if all of today’s female population grow up to have an average of 2.1
children:
• The world’s pop. would continue to grow for 50 years more because there are
so many girls under age 15 who will be moving in their reproductive years
11. Total fertility rate (TFR)
•The average number of children born to women in a population during
their reproductive years
•Between 1955 and 2010:
• the average TFR dropped from 2.8 to 1.7 children per woman in more-
developed countries
• and from 6.2 to 2.7 in less-developed countries
12. Factors affecting birth or fertility rates
•First, The importance of children as a part of the labor force, especially in
less developed countries
•This is a major reason why many poor couples in those countries have a
large number of children
•Parents need help with hauling daily drinking water, gathering wood for
heating and cooking and tending crops and livestock
15. Factors affecting birth or fertility rates
•Second, The cost of raising and educating children
•Birth and fertility rates tend to be lower in more-developed countries
•In more affluent countries, raising children is much more costly
• Children do not enter the labour force until they are in their late teens or 20s
16. Factors affecting birth or fertility rates
•By contrast, many children in poor countries receive little education and
instead have to work to help their families survive
17. Factors affecting birth or fertility rates
•Third, The availability of, or lack of, private and public pension systems
•Pensions reduce a couple’s need to have many children to help support
them in old age
18. Factors affecting birth or fertility rates
•Fourth, Urbanization
•People living in urban areas usually have better access to family planning
services, and tend to have fewer kids than do those living in rural areas
19. Factors affecting birth or fertility rates
•Fifth, Educational and employment opportunities available for women.
•TFRs tend to be low when women have access to education and paid
employment outside the home
20. Factors affecting birth or fertility rates
•In less-developed countries, a woman with little or no formal education
typically has 2 more children than does a woman with a high school
education
•In nearly all societies, better educated women tend to marry later and
have fewer children
21. Factors affecting birth or fertility rates
•Sixth, Average age at marriage or the average age at w/c a woman has
her first child
•Women normally have fewer children when their average age in marriage
is 25 or older
22. Factors affecting birth or fertility rates
•Seventh, Availability of legal abortions
•Each year about 190M become pregnant
•The UN and the Alan Guttmacher Institute estimate that at least 40M of
these women get abortion
23. Factors affecting birth or fertility rates
•Currently, around 43.8M abortions occur worldwide each year
•49% take place under unsafe conditions, resulting in the death of nearly
47,000 women annually
24. Factors affecting birth or fertility rates
•A woman in a developing country is more likely to have an abortion under
unsafe conditions
•Over 94% of women in developed countries take place in conditions
deemed to be safe, compared to only 56% in developing countries
25. Factors affecting birth or fertility rates
•Today, there are 68 countries that either prohibit abortion entirely or
permit it only to save a woman's life, including the Philippines
•There are 58 countries that permit abortion w/o restriction regardless of
the reason, including China and the USA
26. Factors affecting birth or fertility rates
•Eighth, Availability of reliable birth control methods
•Allows women to control the number and spacing of the children they
have
27. Factors affecting birth or fertility rates
•Ninth, Religious beliefs, traditions and cultural norms
•In some countries, large families are favored as people there oppose
abortion and some form of birth control
28. Death Rate
•The rapid growth of the world’s population is primarily because of a large
decline in death rates especially in less-developed countries
•More people in these countries started living longer & fewer infants died
•This happened because of increased food supplies better nutrition and
improved sanitation
•Also because of medical advances like immunizations and antibiotics,
and safer water supplies
29. Overall Health
•Indicators of the overall health of people in a country or region
• 1. Life Expectancy
• 2. Infant Mortality Rate
• 3. Child Mortality Rate
30. Life Expectancy
•The average number of years a newborn infant can be expected to live
•Life expectancy at birth is also a measure of overall quality of life in a
country & summarizes the mortality at all ages
31. Infant Mortality Rate
•The no. of babies out of every 1000 born who die before their first
birthday
•Infant mortality is viewed as one of the best measures of a society’s
quality of life
•It reflects a country’s general level of nutrition and health care
32. Infant Mortality Rate
•High infant mortality rate indicates insufficient food, also, poor nutrition &
a high incidence of infectious diseases
•Infant mortality also affects the TFR
33. Child Mortality Rate
•The annual number of deaths among children under age 5 per 1000 live
births
•According to the UN, the world’s child mortality dropped 20% between
1960 and 2008; from 20M deaths to 8.8M deaths in 2008
34. Migration
•The movement of people into (immigration) & out (emigration) of specific
geographic areas
•Reasons for migration: seek jobs; economic improvement; religious
persecution; ethnic conflicts
• Also political oppression; wars; environmental degradation
35. How is Population Measured
•Population change of an area can be calculated by:
•Subtracting the no. of people leaving in a pop. (death & emigration) from
the no. entering it (birth & immigration) during a specified period of time
•Period of time is usually 1 year
•Population Change = (Births + immigration) – (Deaths +Emigration)
36. How is Population Measured
•If there are more births than deaths during a given period of time, the
Earth’s population increases
•When the reverse happens, the Earth’s population decreases
•When the number of births equals the number of deaths during a
particular period of time, the global population size does not change
