202. The Tropical Forest
The line of demarcation between the narrow Pacific slope of South America and the broad Atlantic drainage is sharp, especially in the region of Peru. The Cordilleran stretch is arid along the coast, sub-arid in the mountains, unforested in all its most characteristic portions. East of the crest of the Andes, on the other hand, the rainfall is heavy, often excessive, the jungle thick, communication difficult and largely dependent on the waterways. Even the Caucasian has made but the slightest impression on the virgin Amazonian forest at its densest. The Inca stretched his empire a thousand miles north and a thousand to the south with comparative ease, establishing uniformity and maintaining order. He did not penetrate the Tropical Forest a hundred miles. At his borders, where the forest began, lived tribes as wild and shy as any on earth. The Andean civilization would have had to be profoundly modified to flourish in the jungle, and the jungle had too little that was attractive to incite to the endeavor. Some thousands of years more, perhaps, might have witnessed an attempt to open up the forest and make it accessible. Yet when one recalls how little has been done in this direction by Caucasian civilization in four centuries, and how superficial its exploitation for rubber and like products has been, it is clear that such a task would have been accomplished by the Peruvians only with the utmost slowness.
Yet various culture elements filtered over the Andes into the hidden lowlands. The Pan’s pipe, for instance, an element common to the Andes and the Forest, is likely to have originated in the higher center. Elements like the blowgun, the hammock, the chair or stool, are typical of the northern Forest and Antilles, and may have infiltrated these areas from Colombia or even been locally developed. The same is true of the cultivation of the cassava or manioc plant, from which we draw our tapioca. This, the great staple of the Forest region, is better adapted to its humid climate than is maize, which flourishes best in a sub-arid environment. Cassava may therefore be looked upon as perhaps a local substitute for maize, evolved as a domesticated plant under the stimulus of an already established maize agriculture. Its cultivation has evidently spread through the Forest region from a single source, since the specialized processes of preparing it for food—the untreated root is poisonous—are relatively uniform wherever it is grown. Maize is not unknown in the area, but less used than cassava wherever the forest is dense.
A characteristic quality of those Forest culture-traits which are not common ancient American inheritance, is that, whether of Middle American or local origin, they are detached fragments, particular devices having little or no relation to one another, like the hammock and the blowgun, or cassava and the Pan’s pipe. Original fundamental processes, higher accomplishments necessitating order or organization of effort, are lacking. This is precisely the condition which might be anticipated when a culture too low to take over a higher one in its entirety had borrowed from it here and there, as the Forest peoples undoubtedly have borrowed from Middle America.
Three districts within the Forest area have previously been mentioned (§ [174]) as regions in which the forest becomes open or disappears, and whose type of culture is locally modified: Guiana, eastern Brazil, and the Chaco. Of these the Brazilian highlands constitute an area of unusually deficient culture. In parts of them agriculture and pottery seem to be lacking. These highlands are perhaps to be construed as an interior marginal region representing an isolation within the greater Forest area. Had these highlands been in juxtaposition to the Andean area, or even situated near it, they would presumably have been able to take over Andean culture elements more successfully than the low-lying Forest, and would then have stood out from this through superiorities instead of absences. Their remoteness, however, enabled the intervening Forest region to shut them off from Andean influences of consequence, while giving to them only part of its own low cultural content.
The peculiarities of the Chaco are due to the opposite reason. The Chaco is a partly open country at the southerly extremity of the Forest. It lies close to the foot of the Andes where these broaden out into the southern Bolivian plateau. It also shades off into the treeless Patagonian region. It is thus open to influences from three sides, and its culture appears to represent a mixture of the three adjacent ones. The basis would seem to be the culture of the Tropical Forest, but definite Patagonian as well as Andean elements are traceable.