Earth as an Island
¨ Earth is similar to as island because all the organisms that live on Earth share
a limited resource base and depend on it for their long-term survival.
¨ Humans participate in food webs and chemical cycles which provide
breathable air, drinkable water, and fertile soil.
¨ Ecosystem processes provide us with “services” such
as storage and recycling of nutrients.
¨ If we don’t get these “goods and services” from
the environment, we will need to spend money to produce them
¨ The human activities that affect the biosphere are:
Ø Hunting and gathering
Ø Urban development
Hunting and Gathering
¨ Our ancestors obtained food by hunting and gathering.
¨ This practice caused a mass extinction of animals in North America about 12,000 years ago.
¨ Today, groups of people scattered around the world still follow
the hunter-gatherer way of life to some degree.
¨ Most of them use some form of technology, such as guns, snowmobiles,
or manufactured tools.
¨ By the end of the last ice age-about 11,000 years ago, humans began
the practice of farming, or agriculture.
¨ The development of agriculture also included raising animals.
¨ The spread of agriculture was among the most important developments
in human history.
¨ It provides a dependable supply of food that can be produced in
large quantity and stored for later use.
¨ This lead to large settlements and stable communities.
From Traditional to Modern Agriculture
¨ Farmers eventually acquired machinery to help with cultivation.
¨ World exploration led to an exchange of crops around the globe.
¨ Advances in technology also lead to large scale irrigation in dry
areas such as the western United States
allowing deserts to become breadbaskets.
¨ Agricultural scientists developed new varieties of crops that produce
¨ These crops were grown using monoculture in which large fields are planted with a single variety year after year.
¨ Chemical fertilizers boosted plant growth and pesticides controlled
The Green Revolution
¨ The green revolution
greatly increased the world’s food supply.
¨ Plant breeder’s developed highly productive “miracle
strains” of wheat and rice.
¨ Modern techniques were also introduced to countries that were suffering
from food shortages.
v Mexican farmers increased their wheat production ten times in 20
v India and China
produced enough food to feed their own people for the first time in years.
¨ The green revolution has helped world food production double.
Challenges for the Future
¨ Modern agriculture has created ecological challenges.
Insect pests and diseases cause farmers to increase
the use of pesticides which:
Contaminate water supplies
Damage beneficial insects
Accumulate in the environment
Finding enough water for irrigation
The West and Midwest
depend on the Ogallala aquifer (underground water deposit).
It is expected to run dry within 20 to 40 years.
¨ Ecologists conclude we need to maintain the benefits of modern agriculture while
developing new approaches to protect natural resources.
Industrial Growth and
¨ The Industrial Revolution transformed human society by adding machines
and factories during the 1800’s.
¨ Mass-produced farm machinery makes efficient, large-scale agriculture
¨ Automobiles give us mobility.
¨ Energy is produced from fossil fuels-coal, oil, and natural gas.
¨ Certain kinds of industrial processes pollute air, water, and soil.
¨ Dense human communities produce wastes that must be disposed of.
¨ Suburban growth consumes farmland and natural habitats placing stress
on plant and animal populations.