488 FOOD PLANTS OF ANCIENT AMERICA. 



adopted very far back to make possible the ancient domestication of 

 2Ian)hot (cassava), CoJoeasia (taro) and Xantlwmma (3'autia), since the 

 fleshy underground parts of these plants contain substances distinctly 

 deleterious and extremely unpalatable until disintegrated and rendered 

 harmless and tasteless b}^ heat. The same may have been true of the 

 sweet potato/' since the fleshy roots of its uncultivated relatives are 

 strongly purgative. Several of the yams, both wild and cultivated, 

 are also poisonous in the raw state. 



That these poisonous root crops were the most popular, widespread 

 and ancient would seem to afford sufficient proof that the discovery of 

 the use of fire in cooking preceded the development of the art of agri- 

 culture, though further support may be derived from the verj^ practi- 

 cal consideration that without fire the primitive savage with his 

 stone ax would make little headway in the work of clearing away 

 the forest, . which is everywhere the first preliminary of tropical 

 agriculture. 



To be able to utilize as nourishing food the natural supplies of 

 starchy roots, which to other tribes were poisonous, would give the 

 primitive fire users an important advantage over their neighbors, and 

 would greatly conduce to the adoption of a settled existence in dis- 

 tricts where the plants were plentiful. Cassava, yams, taro, sweet 

 potatoes, and others of the primitive series of root crops often grow 

 freely and without care from rejected fragments or pieces of stem, so 

 that the digging of the roots and trampling down of the vegetation 

 would not exterminate the wild supply, but would afford, on the 

 contraiy, abundant opportunity and encouragement for the gradual 

 increase of cultural efforts. 



A third important step in the domestic economy of primitive man 

 was the making of dr}^ meal or starch from roots, accomplished in the 

 tropics of both hemispheres b}- similar processes of grating, soaking 

 in water, boiling, or treating with alkalis to destroy their poisonous 

 properties. Separated from the sugars and other readily soluble sub- 



«A plant which may be the wild ancestral form of the sweet potato is a common 

 weed in the C'oban coffee district of eastern Guatemala. The absence of the sweet 

 potato from Samoa, Fiji, Guam, and the Philippines may have inclined some to doubt 

 its prehistoric distribution in the Old World west of Hawaii and New Zealand, but 

 according to Bretschneider it is recorded in Chinese books of the second or third 

 century of the Christian era, and there are many varieties with native names in trop- 

 ical Africa, both east and west, and legends indicative of its presence in early times. 



"It is told me as truth, that before the Portuguese came to this coast (Guinea), 

 the negroes subsisted themselves with these two fruits (yams and sweet potatoes) 

 and a few roots of trees, they being then utterly ignorant of ]\Iilhio (maize), which 

 was brought hither by that nation." (Bosnian's Guinea (1698) in Pinkerton's 

 Voyages, vol. 16, p. 459.) 



Cheeseman records two varieties of the sweet potato as existing in Rarotonga 

 before the arrival of Europeans, and believes that the plant has been cultivated 

 there "from time immemorial." (Trans. Linn. Soc. Lond., 2 sen, 6:289, 1903.) 



