Studying Human Populations

A public beach in China. China has one of the largest populations in the world with more than 1 billion people

Studying Human Population

• Demography – the study of populations– The historical size and makeup of populations– Properties that affect population growth

(economics & social structure)

• Developed Countries = higher incomes, industrial economies, slower population growth

• Developing Countries = lower incomes, agricultural economies, faster population growth

The Human Population Over Time• http://www.pbs.org/wgbh/nova/worldbalance/numbers.html

• After growing slowly for thousands of years, the human population grew exponentially in the 1800s.

• Why? – Increases in food production– Improvements in hygiene & medicine

The USA POPULATION DENSITY

RANK STATE

POP. DENSITY

1 NJ 1205 pp/mi2

2 RI 1016 pp/mi2

3 MA 852 pp/mi2

4 CT 741pp/mi2

5 MD 606 pp/mi2

6 DE 471 pp/mi2

7 NY 415 pp/mi2

8 FL 360 pp/mi2

9 PA 285 pp/mi2

10 OH 282 pp/mi2

Forecasting Population Size• Age structure – distribution of ages in a

specific population at a certain time.– Ex: if a population has more young people

than old people, that the population will likely increase.

– Population pyramid – graphs age structure

Forecasting Population Size• Survivorship – percentage of members of a

group that are likely to survive to any given age.

Demographers study groups of people born at the same time and notes when these people die.

Type I survivorship curve = people live to be very old.Type II survivorship curve = similar death rate at all agesType III survivorship curve = many people die young

Forecasting Population Size• Fertility Rates – the number of babies

born each year per 1000 women in a population– Replacement level = the average number of

children each parent must have to replace themselves in the population = 2.1 b/c not all children will survive & reproduce.

Total fertility rate in the United States.

• Migration – the movement of individuals between areas– Immigration = movement into an area– Emigration = movement out of an area

Forecasting Population Size

Population of the United States

Declining Death Rates• Death rates have declined

more rapidly than birth rates because of:

• an adequate amount of food resources

• clean water• safe sewage disposal• vaccinations.

• Life expectancy – average number of years a person is likely to live.

Women & Fertility• Increased education and economic independence

for women = declining birth rates.• Why?

– Learn family planning techniques– Do not need children to ensure survival– Contribute to family’s prosperity by working– Children are expensive in modern societies

Changing Population TrendsA rapidly growing population uses resources at

an increased rate and can overwhelm the infrastructure of a community.

Infrastructure – basic facilities & services that

support a community (water supplies, sewer

lines, power plants, roads, schools, hospitals, etc.)

Problems of Rapid Growth1) Shortage of Wood &/or Fuel

2) Unsafe &/or Limited Water Supplies

3) Land ImpactsA) Shortage of arable land – land that can be used for

crops

B) Urbanization – movement of people into cities

C) Suburban sprawl – people living in suburbs, causing traffic jams, inadequate infrastructure, and reduction of land for farming or wildlife habitats

Which regions of the world will contribute the most population growth?

Managing Development & Population Growth

Less developed countries know that continued population growth can limit their economic development. Some countries have tried to reduce birth rates

using: -public advertising

-family planning programs

-economic incentives

-legal punishments

Growth is SlowingHuman population is more than 6 billion and

increasing. If people worldwide practice replacement level reproduction, the population in 2050 will be around 9 billion. It will be much higher without planned reproduction.

USA Population Growthhttp://www.census.gov/population/www/popclockus.html

US Population1950 = 150,000,0001998 = 270,000,000By 2050 = 430,000,000

*How fast is the US population increasing?

*What is causing this growth?