Artificial cranial deformation in Tiwanaku, Bolivia

Herein lies a brief historical review of the practice of artificial cranial deformation (ACD) in Tiwanaku, Bolivia, a pre-Columbian archeological ruin once regarded as one of the most powerful pre-Inca regions whose influence extended into present-day Peru and Chile from 600 to 1000 AD. We describe the history, purpose, and implications of ACD from both a neuroanatomical and cultural perspective.

A literature review was conducted through PubMed on the history of artificial cranial deformation in South America, concentrating on the Tiwanaku region. The authors searched all available data with no specific time reference, using the mentioned keywords: ACD, neuroanatomical implications of ACD, cultural and social functions of ACD, Tiwanaku society, and Andean civilization.

Early Andean civilization was hierarchical and stratified. In Tiwanaku, the practice of ACD served to delineate one's social class, caste, lineage, and vocation. This was especially useful for warriors, who distinguished their fellow combatants from insurgents by differences in their cranial structure. ACD was usually conducted within the first few months of an infant's life before morphogenetic features became permanent. Two popular cranial styles-tabular and annular-were achieved by applying various mechanical apparatus and resulted in several cranial shapes (conical, box-like, flattened, etc.). Neuroanatomically, each deformation technique and the duration for which mechanical stress was applied influenced the solidification of cranial bones and shaped the frontal, occipital, parietal, and temporal bones differently. Cognitive deficits and plagiocephalic defects were recorded in limitation and may have been overlooked as the era's occupational demands were more labor-intensive than knowledge-driven.

In Tiwanaku, the custom of ACD was used to demonstrate group identity, with alterations of the cranial shape corresponding to a particular headdress. ACD was used to distinguish an individual's social identity, separating different groups of society into castes, classes, and slaves (Brain, 1979). The custom has also been used to mark territory and emphasize ethnic differences among groups, with potential cognitive implications that were largely unrecorded.