Human population growth – Facts:

IS THIS OUR FUTURE?From TOLES The Buffalo News

(Cunningham and Saigo 1999, p.138)

Human population growth – Facts:

Every second an average of 4.5 children are born and 2 people die net gain = 2.5 people/second

9,000 people/ hour216,000 people/day79 million people/year

It took 2 million years to reach 1 billion people (1825)

• 100 yrs to reach 2nd(1925)• 35 yrs to reach 3rd (1960)• 15 yrs to reach 4th (1975)• 12 yrs to reach 5th (1987)• 12 yrs to reach 6th (1999)

Kaufman and Franz 2000, p.156

How did we get here?

• 3 main strategies or circumstances– Expansion into new habitats– Increasing carrying capacity of habitats already

inhabited– Removal of limiting factors

1 - Expansion into new habitats

• Early humans limited to savannahs– Mostly gatherers of vegetables and scavengers of meat

• By 200,000 ybp hunter/gatherers had appeared• By 40,000 ybp hunter/gatherers had spread through

much of world

Expansion was much more rapid than most animalsAnd it was enabled by . . . ?

2 - Increasing carrying capacity of habitats already inhabited

• 4 “revolutions”– Cultural = use of tools – questionable date

Allowed more efficient hunting and gathering

– Agricultural = domestication of animals and wild plants and irrigation ~10,000 ybp

Increased food increased population towns and cities social hierarchy with division of labor more intensive ag increased food . . .

– Industrial/technological ~ 1600 A.D.

– Green = hybridization of crops (mid 1970s) , fertilizers, pesticides, insecticides and better irrigation (1950s on)

3 - Removal of limiting factors• Until middle ages the effect of high birth rate was

cancelled out by disease, famine, war, cultural taboos, and conscious control of populations through practices such as infanticide

• Technogical revolution led to germ theory 300 ybp– Bacteria and viruses recognized as disease agentsDevelopment of vaccines, early antibiotics,

disinfectants, better hygiene, sewage treatment, plumbing

So what is our carrying capacity?

• Why is it difficult to know?

So what is our carrying capacity?• Why is it difficult to know?

– No equation for K for humans – we can’t experiment to find out!

– Geopolitical boundaries are not the same as environmental boundaries - K for one country is different from K for an other or for the globe

– We can change our K– Do we want to determine human K based only on

survival?• Brings up CULTURAL CARRYING CAPACITY

What is the world population’s

ecological footprint?

• Cultural carrying capacity = the population size the environment can sustain over a long period of time with a given technology, standard of living, and associated pattern of living

• I = PATEnvironmental impact =

population X affluence X technology

2 classic views of limits to growth:• Thomas Malthus – 1798 – An Essay on the Principle of Population

as It Affects the Future Improvement of Society, with Remarks on the Speculations of Mr. Godwin, M. Condorcet, and Other Writers

– To refute “progressives’ and optimists’” predictions of utopian society

– Population grows geometrically, but food only grows slowly– Only way to stabilize population is by:

• Positive decreases – disease and famine• Preventative – “moral restraint”

– Most people are too lazy or immoral to voluntarily reduce population, so shouldn’t feed the poor

• Karl Marx – vehement critic of Malthus– A “shameless sycophant of

the ruling class”– believed that population

growth was a symptom, not a cause, of social ills

– Population grow is caused by oppression and exploitation

Do these views still apply today?

Still have classism, exploitation, etc.But, at some point human population growth has to

be limited.

Neo-Malthusians – think should address population problem directly and quickly, and birth control should be our highest priority

Neo-Marxians – think only eliminating oppression and poverty through technology will solve population problems

How do we measure populations?

1. Number of people 10 Most populous countries in 2025

(estimated, in millions)Country 1950 1995 2025China 555 1221 1526India 358 936 1392US 152 263 331Pakistan 39 140 285Indonesia 79 198 276Nigeria 33 112 238Brazil 53 162 230Bangladesh 42 120 196Mexico 28 94 137Ethiopia 18 55 127

2. Growth rate

3. Doubling time

4. Population density

• Demography = vital statistics about people= scientific study of the sum of individual acts as

they affect population measures

- Goal is to understand the causes and consequences of changes in population

- Can help in planning- To understand significance of demographic

statistics, must understand the culture

Factors affecting human population change

• Population change = minus

births + immigration

deaths + emigration

Some demography definitions• Fertility = how many

children a woman will bear in her life

• Crude birth rate = # of live births per 1,000 people

• Crude death rate = # of deaths per 1,000 people

• ZPG = zero population growth

= when B+I = D+E

What do demographic stats tell us about quality of life?

• Several important ones:– Population density– Urbanization– Life expectancy– Infant mortality rate– Female literacy

Countries with high and low fertility rates 10 highest 10 lowest

Total fertility 7.25 1.4Birthrate 49.8 10.4Death rate 16.8 10.6Annual increase 3.6

0.002Infant mortality 111.1 10.8Female literacy 24.5 > 95GNP per capita $866 $13,049

The demographic transitionBased on early industrial nations in Europe

Demographic transition in developed versus developing countries

Demographic transition in US

Population profiles

US baby boom generation profile

So what implication does this have on the demographic transition of

developing countries today?• Huge percentage of children – not yet into

childbearing years• What will happen as they rise through the

pyramid?

The demographic trap

Falling living standards (due to rapid increase in population?)

reinforce high fertility ratesreinforces decline in living standards

High birth rates + low death rates + huge backlog explosive population growth

So what can be done?

• Regulation – government population policies– Pronatalist = encourages childbearing– Antinatalist = discourages childbearing

• Family planning• Education

Factors affecting birth control use