362 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
respects much like our own. Among factors of production, we should 
not minimize strong government—witness the pyramids, a burst of 
energy covering only 150 years out of 5,000. 
It is now generally agreed that the wheel and axle, the cart and the 
beast-drawn plow were first used somewhere between the Persian Gulf 
and the Syrian shore at or about 4000 B. C.—perhaps earlier. It is 
further agreed that this important invention was made only once 
in human history. The spread of the wheel and axle to all continents 
has been definitely traced from this one source. 
Archeologists are continually finding proof that commerce existed 
at this early time between Egypt, Mesopotamia, and the Indus Valley. 
WHEAT CULTURE 
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ANTIQUITY 
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SS 6... 
FieuRE 3.—Wheat culture in antiquity. (After Carl Bishop.) Wheat had 
climatic limitations to its spread. It does not thrive in the wet Tropics. 
Because of these exchanges these earliest centers of heavy population, 
cities and city culture may legitimately be considered one civilization 
in a sense similar to our use of the term Western Civilization. 
This new culture of the three valleys with its stupendous advance 
over previous cultures was, at base, a result of the enduring soil 
fertility. For the first time in human history large sedentary popu- 
lations could depend upon the permanence of their food supply. 
Generation after generation men could live in the same place. They 
could accumulate things. They had leisure. When they learned to 
write, they soon recorded knowledge and built libraries in which to 
store it. Thus three dry valleys became the cradles of civilization 
