Transcript Chapter 15 Lessons from the Past, Lessons for the Future.

Chapter 14
Lessons From the Past, Lessons
For the Future
Chapter Outline
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How Successful Are We?
Humans and the Impact of Culture
The Loss of Biodiversity
The Present Crisis: Our Cultural
Heritage?
Neolithic
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The period during which humans began to
domesticate plants and animals.
The Neolithic is also associated with
increased sedentism.
Dates for the Neolithic vary from region to
region, depending on when domestication
occurred.
Mesolithic
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The period preceding the Neolithic, during
which humans increasingly exploited
smaller animals (including fish), increased
the variety of tools they used, and
became somewhat less nomadic.
Map of Deforestation
The Loss of Biodiversity
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Biodiversity is the totality of all living things,
from bacteria and fungi to trees and humans.
We are currently losing biodiversity, but we
don’t know the exact rate of loss or what its
impact will be.
The geological record indicates that in the past
570 million years, there have been at least 15
mass extinction events, two of which altered all
of the earth’s ecosystems.
Mass Extinction Events
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The first occurred 250 million years ago and
resulted from climatic change following the
joining of all the earth’s landmasses into one
supercontinent.
The second event happened 65 million years
ago and ended 150 million years of evolutionary
processes that produced the dinosaurs.
 This is believed to be the result of climate
changes following the impact of an asteroid.
Mass Extinction Events
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A third major extinction event is occurring now, and may
have begun in the late Pleistocene or early Holocene
 Many scientists believe several large mammalian
species were pushed toward extinction by humans,
near the end of the Pleistocene, some 10,000 years
ago.
 In North America, at least 57 mammalian species
became extinct, including the mammoth, mastodon,
giant ground sloth, saber-toothed cat, several large
rodents, and numerous grazing animals.
Overpopulation
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Scientists estimate that around 10,000
years ago, only about 5 million people
inhabited the earth.
By A.D. 1650, there were perhaps 500
million, and by 1800, 1 billion.
Between 10,000 years ago and A.D. 1650
population size doubled 71 times.
Overpopulation
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Dates and associated population
estimates up to the present are as
follows:
 mid-1800s, 1 billion
 1930s, 2 billion
 mid-1960s, 3 billion
 mid-1980s, 4 billion
 present, 6 billion
Line Graph Depicting Exponential
Growth of Human Population
The Greenhouse Effect And
Global Warming
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Activities involved in the production of goods
and services produce waste and pollution, all of
which leads to environmental degradation.
Much of the energy used for human activities is
derived from burning of fossil fuels.
Burning fossil fuels releases carbon dioxide into
the atmosphere, and this, in turn, traps heat.
Deforestation
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Deforestation contributes to global warming,
since we’re reducing the number of trees
available to absorb carbon dioxide.
In the tropics, trees are burned as land is
cleared, a practice that releases yet more
carbon dioxide.
An estimated 20% of all carbon dioxide
emissions are accounted for by the burning of
the Amazon rain forest alone.
Climate Change
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Since records began being kept in 1860, the
1990s were the hottest decade, followed closely
by the 1980s.
The year 2002 had the distinction of being the
warmest year on record, with 1998 running a
close second.
The summer of 2003 was the hottest on record
in Europe, and for the first time in recorded
history, the temperature reached 100°F in
London.
Climate Change
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According to the U.N. Intergovernmental Panel
on Climate Change, the average surface
temperature of the earth increased by 0.8 C
between 1961 and 1990.
An increase in the mean annual temperature
worldwide of 0.5–1°C could result in melting of
the polar caps and flooding of coastal areas.
Experts believe Greenland’s ice sheet will
disappear if temperatures increase 3.0°C.
 This could raise sea levels by as much as 23
feet over the next 1000 years.
Quick Quiz
1. The population of the world today is
around ______ billion.
a) 2
b) 4
c) 6
d) 10
Answer: c
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The population of the world today is
around 6 billion.
2. The adaptive strategy of humans has
always been
a) fight or flight.
b) culture.
c) aggression.
d) expansion.
Answer: b
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The adaptive strategy of humans has
always been culture.
3. In the past 570 million years, there have
been ______ mass extinctions.
a) 4
b) 10
c) 15
d) 21
Answer: c
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In the past 570 million years, there have
been 15 mass extinctions.
4. The problem that is linked to all other life
forms and is therefore the most
important problem facing human beings
is
a) population increase.
b) competition for resources.
c) polluted air.
d) loss of biodiversity.
Answer: a
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The problem that is linked to all other life
forms and is therefore the most
important problem facing human beings
is population increase.