Page 138 - ABCTE Study Guide_Neat

Previously Covered

The previous lesson reviewed some basic economic concepts, including the price index, gross domestic
product, and exchange values.

Physical Geography and Civilization

The natural world has shaped the contours of our existence from earliest prehistory up to the present.
Indeed, civilization itself only sprang into being after the glaciers of the last ice age had receded from
North America and Northern Europe. Paleoanthropologic studies show that humans intermittently
practiced a kind of proto-farming for thousands of years prior to the Agricultural Revolution. They did not,
however, intervene intensively in the breeding and cultivating of crops, nor did their semi-wild gardens
become mainstays of the prehistoric diet. Within a few thousand years of the present interglacial period,
however, full-scale agriculture was practiced by cultures around the world. Scientists still debate the
reason for a sudden, global interest in a technology that had been only sporadically employed before that
time, but many believe that the climactic instability inherent in the last ice age prevented cultures from
being able to develop long-lasting permanent settlements. After the last ice age, however, the climate
stabilized sufficiently to allow for long-term agricultural investment.

The other major environmental factor necessary to the rise of civilization was water, usually in the form of
a regularly-flooding river. All of the major early civilizations arose in major river valleys: Sumer and the
subsequent Mesopotamian civilizations developed in the fertile land between the Tigris and Euphrates
rivers; the Egyptian Dynasties came to power along the Nile river; and the Harappa civilization of India
sprang up by the Indus. Rivers, aquifers, and other bodies of water that sustained agriculture and
facilitated travel, trade, communication, as well as the spread of ideas. Water and its movement (shown
below) is the lynchpin of human life. This will be covered with greater detail in the Life Science chapter
coming up.

The water cycle