9. Age Structure & Human

Our species went from Africa

to other parts of the world

Humans are

EVERYWHERE

Modern humans

Sunlight, farming, crops, dirt, water

Human populations are

urban, sub-urban, city

Human population size

• 8, 183, 611, 916

• Projected 9.4, billion by 2050

Human population growth

super slow, then BAM industrial revolution

Human population dips due to

plauges

Human population is no longer growing exponentially but

is still increasing extremely rapidly (pressure on nonrenewable resoruces)

Global human populations are experiencing demographic transitions

• to maintain population stability, a regional human population can exist in one of two configurations

• 1) 0 growth = high birth rate - high death rate

• 2) 0 growth = low birth rate - low death rate

• the demographic transition is the move from the first state to the second state

• the ability to control family sizes through planning and coluntary contraception helps decreases population growth

One important factor affecting population growth is a country’s age structure

• age structure is the relative number of individuals of each age in a population

• age-structure diagrams (pyramids) can help predict a population’s growth trends

• they also illuminate social conditions and help us plan for the future

Country’s age structure

proportion of individuals in different age classes

Pyramid structure

• Pyramids with broad bases: a growing population (india)

• Pyramids with narrow bases: a declining population (germany)

• pyramids with straight sides: a stable population (us)

Human societies

• consumption of resources - linked to income

• waster disposals sites

• technology

• land transformation: crops, cattle, timber, roads, streets, building, etc

Human ecological footprint

Measures the amount of land area (global hectares) and energy needed to support an average citizen of a nation

Different countries have different impact

• the impact (I) of any human population on the environment is captures by the formula

• I = PAT

• P = number of people

• A = average income

• T = level of technology

Ecoloical footprit per captia

qatar, luxembourg, untied arab, emirates, USA, China