lines were the pathways for important ceremonial processions. The lines have been studied by experts from several disciplines. Anthropologists, archaeologists, and astronomers have all studied the lines, but have not found conclusive evidence for any of the theories as to purpose. Trephination and cranial manipulation Trephination was a primitive skull surgery used by the Nazca that relieved pressure on the brain from battle wounds or for ritual purposes. It entails the removal of one or more sections of bone from the skull (while the person is still alive). Evidence of trephination has been seen through the analysis of excavated skulls. Some of the skulls show signs of healing, evidence that the person had survived the operation. Elongated skulls, as a result of skull manipulation, were also seen in the excavations from Cahuachi. This effect was achieved by binding a cushion to an infant's forehead and a board to the back of the head. Archaeologists can only speculate as to why this was done to some of the skulls. Several theories suggest skull manipulation created an ethnic identity, formed the individual into a social being, or may have illustrated social status. Some historic Native American cultures in North America also practiced such shaping of skulls, such as the Snake, Cowlitz and Chinook peoples, most of whom lived west of the Columbia River in the Pacific Northwest. They were informally known as the Flathead peoples. See also Wari Empire References Bibliography Local Differences and Time Differences in Nasca Pottery by Donald A. Proulx (1968) University of California Press The Incas and their Ancestors: The Archaeology of Peru by Michael E. Moseley. 1992. Cahuachi in the Ancient Nasca World Silverman, Helaine. University of Iowa Press. Iowa City. 1993. "The Archaeological Identification of an Ancient Peruvian Pilgrimage Center" by Helaine Silverman, World Archaeology 26, no. 1 (June 1994): 1–18 "Paracas in Nazca: New data on the Early Horizon Occupation of the Rio Grande de drainage, Peru" Silverman, Helaine. (1994) Latin American Antiquity, Vol. 5, No. 4, pp. 359–382. Early Nasca Needlework by Alan R. (1996) Sawyer Laurence King. Der Nasca-Ikonenkomplex: Seine mythischen Gestalten und ihre Entwicklung, erschlossen aus den Darstellungen gegenständlicher Bildwerke/Nasca Iconography. Its mythical Figures and their Evolution, established on the Basis of Pictorial Works, by Christiane Clados, Dissertation, Free University BerlinThe Nasca by Helaine Silverman and Donald A. Proulx. Blackwell Publishers. Malden. 2002.Ancient Nazca Settlement and Society by Helaine Silverman (2002) University