Whether this high specialization of cultivated plant life can be used as an indication of greater age on the part of American agriculture in comparison to that of the Old World is a difficult point. In the writer’s opinion it may indicate merely a greater agricultural awareness on the part of the Indian, a cultural trait no doubt strongly furthered by the relative unimportance of domesticated animals.[20]
[Illustration: _Corn of 4,500 years ago, as reconstructed from a cob found in Bat Cave, New Mexico. (After Mangelsdorf and Smith, 1949.)_]
Sylvanus G. Morley believed that the Maya cultivated corn at a time close to 1000 B.C.[21] which was, of course, no more than a guess. MacNeish states that the most ancient corn of the Maya area, found in the gulf state of Tamaulipas, dates from about 5,000 years ago.[22] We may presume that the Maya were cultivating it some centuries earlier. Antevs gives a date of “not later than 2500 B.C.” for a layer of refuse in Bat Cave, New Mexico, in which Herbert W. Dick found the cobs and kernels of a primitive form of maize that is both a pod corn and a pop corn. These cobs—now dated by radiocarbon at about 5,600 years ago[23]—range from 2⅜ inches to 3¾ inches in length. Though probably not specimens of the long-sought wild corn, they are not far removed in characteristics.[24] In coastal Peru—where corn could not have started—Julio C. Tello found kernels in the ruins of Paracas, along with manioc roots, sweet potatoes, and beans. There is a radiocarbon date of about 2,250 years ago for cotton cloth from a mummy found at Paracas.[25] In a preceramic culture about 5,000 years old,[26] Duncan Strong and Junius Bird found no corn, but evidence that these early agriculturists had raised cotton, squash, and other plants.[27]
It seems unlikely that any form of agriculture could have been developed from native plants in coastal Peru, for it is as arid a spot as can be found anywhere in our hemisphere. Only an elaborate system of irrigation canals enabled this area to grow extensively corn, beans, and other plants. In the highly developed civilization of the coast—so close to the guano islands—the Indians started the use of fertilizers, which was to be a feature of Peruvian agriculture. The development of irrigation and fertilizer, plus city architecture and the finest pottery in the Americas, spells many years of slowly growing civilization in coastal Peru, and behind these beginnings must have lain centuries upon centuries of earlier agricultural discoveries and improvements in the hinterlands. The only alternative is to accept the diffusion of a full-blown culture across the Pacific.