258 ORIGIN AND DISTRIBUTION OF THE COCOA PALM. 
anthropologists. Thus the evidence of the existence of the banana in 
prehistoric America is equal, if not superior, to that here presented 
for the cocoanut. The banana and the sweet potato, both grown in 
cultivation only from cuttings, crossed the Pacific before the advent of 
Europeans; and this fact, not to mention here others of similar import, 
goes far to render probable the human distribution of the cocoa palm. 
At the same time it tends to demonstrate that the prehistoric trans- 
Pacific communication, of which evidence is now being sought with 
great diligence and expense in Alaska and Kamchatka, took place 
within the Tropics. An ecological investigation of the peoples of 
the shores and islands of the Pacific, giving special attention to the 
species and varieties of their food plants, might be undertaken with 
reasonable prospects of decisive results upon many questions now 
approached only by theory and conjecture, and upon which little light 
can be expected from the tribes of the polar regions, who long since 
left-behind them, not only their tropical economic plants, but all the 
agricultural arts and habits which their remote ancestors may have 
possessed. 
Owing to the great antiquity of the beginnings of agriculture the 
origins of many cultivated plants are involved in obscurity. A con- 
siderable proportion of our most important economic species are not 
known in their wild state, presumably because human selection has 
rendered their botanical relationships unrecognizable, or because the 
original wild forms have become extinct. Even in dealing with 
the origins of the temperate plants cultivated in the Mediterranean 
region there are many unsolved problems, notwithstanding the great 
amount of historical and philological testimony available, and it is thus 
only reasonable to expect that the confusion and uncertainty will be 
many times greater with the species domesticated in primitive tropical 
societies the existence and location of which are often little more than 
conjectural. Moreover, in the absence of formal records or historical 
remains, the plants themselves may prove to be the best obtainable 
clew to the locations and movements of prehistoric agricultural 
peoples. While in such matters we may not soon, if ever, attain to 
satisfactory definiteness and certainty, it is the more necessary to use 
every fact drawn from general biology or from other collateral sources 
as a view point from which less satisfactory evidence may be inter- 
preted. Pickering was undoubtedly correct in believing that useful 
plants furnish man’s best record of his own primitive existence. 
Unfortunately, that author, so zealous in collecting materials, did not 
have at his command the botanical knowledge required for establishing 
the identifications and origins of individual species, without which 
fixed points of departure can not be secured and distributional studies 
become a tangle of dry and worthless details. 
