chapter 4: part one the human population and the environment

Chapter 4: Part One

The Human Population and

the Environment

Basic Concepts of Population Dynamics

• Population:– A group of individuals of the same species living in

the same area in the same time period

• Species:– All individuals that are capable of interbreeding.– Made up of populations

• Population dynamics– The study of population changes.

• Demography -

Forecasting Population Change

• Formula to represent population change:

P2 = P1 + (B – D) + (I – E)

P =

B =

D =

I =

E =

Age Structure

• Population age structure:– The proportion of the population in each age

class– Affects current and future birth rates, death

rates and growth rates– Has an impact on the environment– Has complications for current and future

social and economic status.

© 2008 John Wiley and Sons Publishers

A Brief History of Human Population Growth1. Hunters and gatherers

• The world’s population was probably less than a few million

2. Early, pre-industrial agriculture• Allowed a much greater density of people• The first major increase in human population

3. Machine age• Industrial revolution led to rapid increase in human

population4. The Modern era

• Rate of population has slowed in wealthy nations but continues to increase rapidly in poorer, less developed nations.

© 2008 John Wiley and Sons Publishers

© 2008 John Wiley and Sons Publishers

© 2008 John Wiley and Sons Publishers

© 2008 John Wiley and Sons Publishers

Projecting Future Population Growth• Exponential growth and doubling time• The logistic growth curve

– “S” shaped curve that is generated by the logistic growth equation.• A small population grows rapidly• But the growth rate slows down• The population eventually reaches a constant

size.• Logistic carrying capacity

– The population size at which births equal deaths and there is no net change in population

© 2008 John Wiley and Sons Publishers

© 2008 John Wiley and Sons Publishers

© 2008 John Wiley and Sons Publishers