/') MILPA AGRICULTURE—COOK, 315 
carried on the backs of men for 2 or'3 leagues, and sometimes for 
much greater distances. Lands suitable for farming have to be 
sought much farther away, often. at a range of 20 or 30 miles. In- 
dians from San Pedro Carcha near Coban may plant milpas in the 
district between Senahu and Cajabon and carry corn home on their 
backs, 50 or-60 miles. 
' The tendency is, of course, for people who raise their crops too 
many miles from the home settlement to spend more time at their 
milpas and carry back less of their corn. Thus an old center is 
likely to lose its population gradually after the circle of exhausted 
land becomes too wide, or the people may migrate together to a new 
district. Native villages in West Africa usually occupy the same 
site for only a decade or two. With nothing in the way of permanent 
buildings or other improvements to interfere, a new location is sought 
as soon as all the forest has been cut within a convenient radius of 
2 or 3 miles. Much larger areas of denudation were formed, no 
doubt, by people who advanced further in civilization and made 
permanent investments of labor in the building of stone houses, 
temples, and monuments, as in Central America. But considering 
that there were no beasts of burden in Central America, and very 
little in the way of navigable rivers, so that transportation was 
limited to human carriers, centers of population could hardly have 
been maintained from lands that were more than 20 or 30 miles 
away. Some families might go farther out to “make milpas” and 
carry in their corn, so as to live in town for a part of the time, but 
large centers would be impracticable on a GuRS of milpa agriculture 
and man-back transportation. 
In other parts of the world where beasts of burden were used, boats 
on rivers, or ships on the sea, supplies could be drawn from greater 
distances, huridreds of miles, if necessary, so that larger and more 
permanent centers of population could be supported, like the ancient 
cities of the Babylonians, Egyptians, Greeks, and Romans. Agri- 
cultural decay and reduced production at home were made good tem- 
porarily by extending the range of commerce, but with ever-increas- 
ing difficulty and eventually disaster. 
The general tendency of civilization is to develop large centers of 
population without corresponding improvement of food supplies, so 
that practical limits are reached. Urban ideas and interests are 
dominant, industrial and commercial activities are preferred, and 
agriculture remains in the background. As more people are drawn 
into cities, supplies have to be brought from greater distances, requir- 
ing more labor and more complex and delicate economic adjustments. 
With the arts of transportation still more improved, our modern 
centers of industrial activity have the entire world in tribute and are 
