492 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 31 



overshadowed our normal and instinctive interest in the welfare of 

 agriculture. No doubt we shall find that agriculture is as necessary 

 to maintain an advanced civilization as it was for the primitive 

 beginnings. 



The ancient Peruvians undoubtedly excelled us in the art of irriga- 

 tion, and they went much further in reclamation of land. Not only 

 were leveling and terracing done to lessen the slopes of hillsides, 

 but also land was constructed even in places that could have had no 

 natural soil, on precipitous slopes or in eroded stream beds. Sub- 

 stantial retaining walls were built and the inclosed space was filled 

 in, below with rubble work for drainage and above with ample 

 layers of good soil, which still raise good crops every year, after 

 centuries of continuous cultivation. In many of the valleys of the 

 eastern Andes all of the cultivated lands are of artificial terrace 

 construction. Rivers were straightened and mountains resurfaced 

 as incidents of these extensive reclamations. The narrow terraces 

 on the slopes of the mountains, of course, have been recognized as 

 artificial, but the vastly more extensive construction of artificial 

 lands in the bottoms of the valleys were overlooked by many trav- 

 elers, as though the terrace walls supporting the different levels 

 were mere fences between fields. The development of such inten- 

 sive methods of agriculture must have required centuries or 

 millenniums. 



DOMESTICATION OF AMERICAN PLANTS 



The many plants domesticated in America are an evidence of the 

 high development of agriculture and of the vast periods of time tha 

 must have been required. The Peruvian region is considered as the 

 chief center of domestication. Between 70 and 80 different species 

 appear to have been domesticated in pre-Spanish times, as indicated 

 by native names and uses. The list includes numerous root and 

 seed crops adapted to the different elevations, also fruits and vege- 

 tables, potherbs, condiments, medicines, intoxicants, fish poisons, dye 

 plants, fibers, and numerous ornamental plants. The ancient 

 Peruvians had potatoes, beans, maize, cotton, peppers, peanuts, 

 cassava, and sweetpotatoes ; also guavas, chirimoyas, avocados, 

 tuberoses, marigolds, and many other fruits and flowers which are 

 still entirely unknown in North America.^ 



Tobacco apparently was known to the ancient Peruvians, but was 

 considered injurious. The chewing of coca leaves was a regular 

 habit before the conquest, as it is at the present time, and an extensive 

 culture of the coca shrub is still maintained in the eastern Andes. 



* A list of names of Peruvian domesticated plants was published in an article on 

 " Peru as a Center of Domestication," Journ. Hered., February and March, 1925. 



