APES Chapters 3.6-3.9

Human grwoth is at an exponential rate due to…

1. increased agricultural output

2. improved sanitation

3. medical interventions- antibiotics and vaccines

4. Human innovations- industrial revolution and our ability to invade new ecosystems adapt fast

What brought the human population to 8 billion people?

better living conditions causing death rate to fall while birth rates still remained relatively high

Malthusian Theory-

British scientist, Thomas Malthus proposed that humans will eventually reach the carrying capacity of earth due to limited food supplies, after which there will be dieback and the human population will decrease.

Factors that drive population growth-

1. population size

2. birth and death rates

3. fertility

4. life expectancy

5. migration

Demography-

the study of human populations and population trends

Immigration-

the movement of people into a country or region, from another country or region

Emigration-

the movement of people out of a country or region

Crude Birth Rate-

the number of births per 1000 individuals per year

Crude Death Rate-

the number of deaths per 1000 individuals per year

Population Change=

(births+immigration)-(deaths+emigration)

Global population growth rate=

((CBR-CDR)/initial population size) x 100%

National Population growth rate

((CBR+immigration)-(CDR+emigration))/initial population size X 100%

Rule of 70

quick method for estimating the doubling time of population

Doubling TIme (years)=

70/growth rate (expressed in %)

Total Fertility Rate (TFR)

an estimate of the average number of children that each woman in a population will bear throughout her childbearing years

• TFR in the US is 1.8, meaning that, on average, each woman of childbearing age gave birth to just under 2 children

• in developing countries TFR is greater than 2.1

TFR is affected by…

• the age at which females have their 1st child and age at marriage

• educational and employment opportunities available to women

• access to family planning (ex. India’s Family Planning)

• religious beliefs and cultural norms

• Government Acts and policies (ex. China’s one child policy)

• Rural to Urban Living

Replacement-level Fertility-

the total fertility rate required to offset the average number of deaths in a population in order to maintain the current population size

Replacment-level Fertility in Dveloped Countries-

the replacement-level fertility is about 2- basically one child to replace each parent; tends to be higher because mortality among young people tends to be higher

If TFR= replacement-level, and immigration=emigration…

Country’s population is stable

Life Expectancy-

the average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average lifespan and death rate in the country (higher w/ healthcare; good predictor of high resource consumption rates and environmental impacts)

Life Expectancy is reported in 3 ways-

• overall population

• males only

• females only

Why do men have higher deaths rates leading to lower life expectancy?

due to more dangerous jobs, more hazardous life-style choices and more likely to die on wars

Infant Mortality-

the number of deaths of children under 1 year of age per 1000 live births

Child Mortality-

the number of deaths of children under age 5 per 1000 live births

Mortality Rates are affected by…

availability of health care, access to food and good nutrition, availability of clean water, sanitation, exposure to pollutants, diseases such as HIV/AIDS, etc.

Characteristics of a country with high life expectancy and low infant mortality rate-

available healthcare, adequate food supply, potable drinking water, good sanitation, and moderate levels of pollution

In a given sector of a country, why does life expectancy and infant mortality differ widely from life expectancy and infant mortality in the country as a whole

socioeconomic disparities, lack of access to good nutrition, lack of renatal care, and government injustices

Net migration rate-

the difference b/w immigration and emigration in a given year per 1000 people in a country (positive net migration rat emeans more immigration)

Migration does not affect the global population but is still an important issue in environmental science. Why?

• movement of people displaced because of diseases, natural disasters, war/political and religious conflict and environmental problems can lead to crowded, unsanitary conditions, and food and water shortages

• movement of people from developing to developed countries tend to increase the carbon footprint of those people

Age Structure Diagram-

a visual representation of the number of individuals within specific age groups for a country, typically expressed for males and females

• describes how members of a population are distributed across age ranges, usually in 5 year increments

• demographers use this data on age to predict how rapidly a population will increase and what its size will be in the future

Population Pyramids-

and age structure diagram that is widest at the bottom and smallest at the top, typical of developing countries

Population Pyramids Typical of Developing Countries-

wide base compared with levels above indicates a population that will grow rapidly due to large number of female in pre-reproductive stage

Population Momentum-

continues population growth after growth reduction measures have been implemented; can indicate how long it takes for changes to affect a growing population

Why does a population continue to grow after birth control policies and voluntary birth reductions?

occurs because there are a relatively large number of females at reproductive maturity in the population

Column Age Structure Diagram-

country with little difference b/w number of individuals in older and younger age groups

What would happen if there were fewer individuals in younger age classes?

Slow growth or no growth at all (The U.S. falls in this category)

Inverted Pyramid Age Structure Diagram-

a country with a greater number of older people than younger people; TFR is below 2.1 and decreasing number of females in the younger age ranges; population will shrink

Theory of demographic transition-

the theory that as a country moves from a subsistence econoomy to industrialization and increased affluence it undergoes a predictable shift in population growth

Affluence-

the state of having plentiful wealth including the possession of money, goods, or property.

Developed Country-

a country with relatively high levels of industrialization and income

Developing Country-

a country with relatively low levels of industrialization

Demographic Transition: Phase 1

Pre-industrial

• slow population growth because high birth rates and high death rates offset each other. CBR=CDR. This is typical of countries before they begin to modernize

• most people are farmers and having many children are assets (jobs such as collecting firewood, tend crops, watch and care for livestock, take care of siblings, and parents (when old)

• Short Life expectancy due to difficult and dangerous working and living conditions

• High infant mortality rate to poor sanitation, disease, lack of food and lack of health care

• EX. Lesotho

Demographic Transition: Phase 2

Transitional/Industrializing

• rapid population growth because birth rates remain high, but death rates decline because of better sanitation, clean drinking water, availability of food healthcare, including childhood vaccinations (CBR>CDR)

  • CBR continues to be high due to population momentum and time needed to implement educational systems and birth control methods

• EX. Kenya, India

Demographic Transition: Phase 3

Industrialized

• Stable population growth as the economy and educational system improve and people have fewer children. CBR begins to fall and population growth slows

• as societies transition from subsistence farming to complex economic specializations, having large numbers of children become and economic burden rather than a benefit. People are earning more

• People are more affluent and spend more time pursuing education and are more likely to have access to birth control

• EX. US, Canada, Australia

Demographic Transition: Phase 4

Post-Industrial

• Declining population growth because the relatively high level of affluence and economic development encourage women to delay having children. CBR<CDR

• fewer young people and higher proportion of elderly people. With fewer people in the labor force, cost of social security and pension plans will increase tax burden on wage earners

• government may offer incentives to encourage families to have more children to offset the demographic shift

• government may encourage immigration to increase the labor force

• EX. Japan, Germany, Portugal, and Italy

Family Planning-

• The practice of regulating the number or spacing of offspring through the use of birth control. Important in transitioning from a Phase 1 to Phase 3 society

• Higher levels of education and affluence lead to lower birth rates