The human population

Population Explosionpopulation explosionThe study of populations is known as

demographyStudy previous trends to create future

predictionsStudy economy and social status

Human population is increasing due to1. Increase in food production2. Technology advancements3. Industrial + scientific revolutions4. Hygiene5. Medication

Tools to help…Age Structure

Categorization of population by agegroups

Age pyramidPlot of births within a pop

High birth rate = more youngthan old

Slow growth = equal distribution

Fertility RateThe number of babies born per year per

1000 womenTOTAL FERTILITY RATE-

Avg # of children given birth to per woman in her lifetime

REPLACEMENT LEVEL-Avg # of children needed per couple to replace

themselves ~2.11972 = first time in US history birth rate was

below replacement level.

Survivorship Curve

Type I- most individuals live to very old age then rapidly die

Type II- Similar death at any age

Type III- many offspring die to reach a certain age then slow die off

Survivorship = % of members of a group likely to survive to a given age

Other factors leading to population changesMigration - movement of individuals between

areasImmigration = movement into an area

Leads to increase in population sizeEmigration = movement out of an area

Leads to a decrease in population size

DECLINING DEATH RATELed to increased life expectancyLIFE EXPECTANCY = avg # of years a

person is predicted to live. Most impacted by infant mortality

Based on parents access to education, food, fuel, and clean water

2009 US life expectancy = 78.2 yearsJapan has longest life expectancy at 82.6World life expectancy = 67.2

Women + FertilityWomen have the largest impact on the

decrease in birthrate… in areas with low birthrates you will notice… Women are more independentAware of better family planning practicesHigher educationChildren become more of a financial burden

because women are no longer home

As growth rate rises so do problems1. Shortage of fuelwood2. Unsafe drinking water3. Negative land impacts

1. Shortage of Fuel woodWood is the main fuel source in many poor

countries.As populations rise more and more trees

begin to be cut and are depleting resources.

2. Unsafe drinking waterWater is breeding ground for disease-causing

organisms.>1.2 billion people had no access to safe

water and over > 3million deaths/yrFuel wood is used to boil water to kill

bacteria + make palatable.Water needed for drinking, bathing, washing,

sewage.

3. Land ImpactsArable land needed for growing of crops to

support a population.Should land be used for agriculture,

housing, or natural habitat?Urbanization- more people moving

towards cities which leads to suburban sprawl.Leads to increase traffic due to infrastructure

overuse, overcrowding of schools, hospitals, etc. Decrease in land because of buildingMore dense population

Demographic TransitionPattern of demographic change from high birth and death rate to low BR and DR.

Stages of the transition1. Preindustrial

1. High BR + DR2. Stable population

2. Transitional1. Population

explosion2. Drop in DR due to

hygiene, education

3. Industrial1. Slow pop growth

bc drop in BR2. Stabilization

when BR and DR become close

4. Post-industrial1. BR below

replacement level

2. Decrease in pop size

Not all countries follow the transitionLeast developed countries

Very little sign of developmentHigh death and high birth ratesAfghanistan, Bangledesh, Cambodia

Developed countriesLow birth rate and low death rate

Developing countriesHigh birth rate and low death rate.

1994 ICPD International conference on Population

and development.1. Reduce infant mortality to <35/1000

births2. Reduce mortality of <5yr olds3. Close gap in maternal mortality4. Increase life expectancy to 75 in dvped

and 70 in developing.5. Create universal access to completion of

primary education.6. Create access to education to women