Cut marks on the protruding neck bones probably indicate the head had been severed by a sharp obsidian knife. Underscoring the point, a ceramic pot known as a head jar rested against the elbow of the skeleton; it depicted a typically decapitated "trophy head," out of which grew an eerie, Halloween-like tree trunk with eyes. According to Donald Proulx, an expert on Nasca pottery and professor emeritus at the University of Massachusetts Amherst, the style of the jar suggests a tentative date of A.D. 325 to 450.
Everything about the burial—the posture of the skeleton, the head jar, and the posture of the body—indicates a deliberate, respectful interment. "You're not going to do that with your enemy," said Conlee, a researcher at Texas State University. Isotope analysis of the young man's bones make clear that he had lived in the immediate vicinity and was thus a local person rather than a foreign enemy captured in war. Conlee suspects the skeleton represents a ritual sacrifice. "Although we find trophy heads spread throughout the Nasca period," she said, "there are some indications that they became more common in the middle and late period, and also at times of great environmental stress, perhaps drought. If this was a sacrifice, it was made to appease the gods, perhaps because of a drought or crop failure."
There is little question that water—or more precisely, its absence—had assumed paramount importance by the endgame of the Nasca culture, roughly between A.D. 500 and 600. In the Palpa area, geophysicists have traced the creep of the eastern margin of the desert about 12 miles up the valleys between 200 B.C. and A.D. 600, reaching an altitude of some 6,500 feet. Similarly, the population centers in the river oases around Palpa moved farther up the valleys, as if they were trying to outrun the arid conditions. "At the end of the sixth century A.D.," Eitel and Mächtle conclude in a recent paper, "the aridity culminated and the Nasca society collapsed." By A.D. 650, the more militaristic Wari (Huari) Empire, which expanded from its base in the central highlands, had supplanted the Nasca in the southern desert region.
"It wasn't just climate conditions that caused the collapse of the early Nasca culture at Cahuachi, and we can say the same thing for the end of Nasca culture in general," Johny Isla told me. "A state of crisis was provoked because water was more prevalent in some valleys than in others, and the leaders of different valleys may have been in conflict."
The legacy of the Nasca lives on in the lines, of course, and although most people come to admire them from the air, what I'd seen and heard convinced me that you can't truly understand the geoglyphs unless you experience them at ground level. In one conversation, Isla had described to me the sensation of walking upon those sacred paths. "You can feel it," he said. Curious about that feeling, I asked him if we could walk several lines on the Cresta de Sacramento, a small ridge north of the town of Palpa.