Nazca iconography suggests that the prestige of the leaders of Late Nazca society was enhanced by successful headhunting. Economy Nazca subsistence was based largely on agriculture. Iconography on ceramics and excavated remains indicate that the Nazca people had a varied diet, composed of maize, squash, sweet potato, manioc and achira, and a small trace of various fish. They also used several non-food crops, such as cotton for textiles, coca, San Pedro cactus, and gourds. The latter were decorated to illustrate activities in daily life. The evidence of cocoa in society can be seen through remains but also in designs on ceramics. Similarly, the hallucinogenic San Pedro cactus has been illustrated in ceremonies on several polychrome pots and bowls. In terms of animal resources, the Nazca made sacrifices of llamas and guinea pigs at Cahuachi. Llamas were also commonly exploited as pack animals, shorn for their wool, and consumed as a source of meat. Based on archaeological evidence, sometime during the Middle Nazca period, the Nazca people created an aqueduct system to sustain life in the exceedingly arid environment. The exact date of construction of the puquios has been debated for some time. Dating of the puquios is quite difficult because of the materials involved in their construction. Attempts at dating the trenches have also been difficult as the puquios were found by excavation. This destroyed the early context by which their dates might have been interpreted. The most promising techniques used to date them thus far has been the AMS (accelerator mass spectrometry) analysis of varnish that has collected on the rocks inside the puquios, as well as the study of settlement patterns in the area. These techniques have placed the original construction of the puquios at the Middle Nazca period, as indicated above. The irrigation system was made up of underground channels, known as puquios, which tapped into the subsurface water. The channels were dug into the mountainside until they reached the aquifers under the surface. The channels were lined with river rocks. They did not use any mortar so that the water would pass into the channels. The water was transported to irrigation canals (acequias) in order to directly supply water for agricultural purposes, or the water was deposited into small reservoirs (kochas) for later domestic use. Numerous access holes or ojos (eyes) were placed along the surface of the underground channels and operated much in the same