Toxicological analyses of preserved hair and nails now make it possible to supplement archaeological and historical evidence with direct information about psychoactive substances consumed by participants in ceremonies. Compounds introduced into the body can become incorporated into keratin, while advances in modern analytical techniques enable their detection at increasingly lower concentrations. This is particularly important for archaeological materials, in which taphonomic processes lead to the gradual degradation and reduction of preserved compound concentrations over time.

The study analysed samples from eight mummified individuals discovered at high-altitude archaeological sites on Ampato and Sara Sara in Peru, and Chuscha, Quehuar, and Llullaillaco in Argentina. The material included hair and nail samples. In the case of longer hair, the segment closest to the scalp was primarily analysed. Hair from the Chuscha mummy was divided into six one-centimetre segments, corresponding approximately to the final six months of life.

The aim of the study was to determine which plants and psychoactive substances may have been used in preparing children for the capacocha ritual and whether their administration followed similar patterns. The analyses targeted, among others, cocaine, benzoylecgonine, cocaethylene, harmine, harmaline, mescaline, bufotenine, N,N-DMT, scopolamine, and atropine. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used to identify and quantify these compounds, and the analytical procedure was validated in accordance with standards applied in forensic toxicology.

Coca leaves during preparations for the ceremony

Cocaine and its primary metabolite, benzoylecgonine, were identified in all analysed hair samples. In an archaeological context, these compounds should be interpreted as evidence of coca leaf consumption rather than the use of cocaine in its modern, purified form. Coca played both practical and religious roles in the Andean world. Historical sources describe its use to alleviate hunger, fatigue, and symptoms associated with high-altitude conditions. At the same time, coca leaves were among the most important offerings made to deities and formed an integral part of numerous ceremonies. Chroniclers also reported that crushed coca leaves were placed in the mouths of individuals sacrificed during the capacocha ritual.

Particularly significant are the positive results obtained for the Chuscha and Sara Sara mummies. Previous studies had not detected the presence of psychoactive substances. The new analyses confirmed their presence, highlighting the importance of re-examining archaeological materials as analytical techniques advance. When compounds are present at very low concentrations, a previous negative result does not necessarily indicate their actual absence.

Differences in Alcohol Consumption

A more varied pattern emerged in the case of cocaethylene, a metabolite formed in the body when cocaine and ethanol are present simultaneously. Its presence therefore serves as an indirect indicator of the concurrent consumption of coca leaves and alcohol, probably in the form of chicha, a traditional maize beer.

Cocaethylene was identified exclusively in hair samples from children found in Argentina—specifically, the Chuscha mummy and the three children from Llullaillaco. However, it should be emphasized that the absence of cocaethylene does not rule out occasional or sporadic alcohol consumption, as a single exposure may not leave a detectable trace in hair keratin.

The most detailed data were obtained from the segmental hair analysis of the approximately eight-year-old girl from Chuscha. Cocaine and benzoylecgonine were detected in all six segments, whereas cocaethylene was found only in the 0–1 cm segment closest to the scalp, corresponding approximately to the final month of life. This change may reflect the transition into the final stage of the ritual. This pattern differs from observations at Llullaillaco, where cocaethylene was detected over a longer period. A comparison of the two sites therefore suggests that preparations preceding the sacrifice did not follow an identical pattern in all cases.

Harmine and the Children from Ampato

One of the most interesting findings was the detection of harmine in samples from the children of Ampato (the Ampato Maiden and Ampato #2 and #3). Harmine occurs in various plants, but its most likely source in the context examined is species of the genus Banisteriopsis or other plants of the family Malpighiaceae containing high concentrations of β-carboline alkaloids. These plants have traditionally been used to prepare the beverage known as ayahuasca. However, neither N,N-DMT nor bufotenine was detected in the samples. Therefore, the results do not allow us to determine the composition of the beverage consumed or to establish whether it corresponded to the form of ayahuasca used today.

At the same time, these compounds were not detected in the hair sample from Ampato #4. Computed tomography findings suggest that Ampato #4 may have undergone secondary burial, potentially as part of a separate ceremony and at a different location, which could explain the differences in treatment.

It also cannot be ruled out that harmine-containing plants were used for their medicinal and mood-modulating properties. The effects of harmine may have helped calm the children and alleviate stress associated with the multi-stage pilgrimage and exposure to extreme altitudes.

A Different Perspective on Capacocha

A comparison of the results obtained from the different sites does not reveal a single universal pattern of psychoactive substance use during the capacocha ritual. Coca leaf consumption appears to have been a consistent element, whereas the presence of cocaethylene and harmine varied between sites.

The results of our team's research support the hypothesis that the course of the ritual may have depended on the nature of the particular mountain deity and local religious traditions. Individual apus had their own distinct characteristics and were associated with specific genders, spheres of influence, and powers over water, weather, and the prosperity of local communities. Such differences may have influenced how ceremonies were conducted and how individuals were prepared to serve, after death, as intermediaries between humans and the supernatural world.

The study also highlights the limitations of toxicological analyses of archaeological materials. Not all compounds are incorporated into hair and nail keratin to the same extent, and isolated episodes of consumption may remain undetectable. Therefore, the absence of a particular substance does not necessarily mean that it was not consumed.

At the same time, obtaining positive results from samples that had previously tested negative demonstrates the importance of re-examining existing archaeological collections. Advances in analytical techniques mean that samples collected many years ago can provide new insights into ritual practices, mobility, diet, and religious traditions.

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The research was conducted in collaboration between the Centre for Andean Studies at the University of Warsaw, the Collegium Medicum of Nicolaus Copernicus University in Bydgoszcz, the Museo Santuarios Andinos at UCSM (Peru), and the Museo de Arqueología de Alta Montaña in Salta (Argentina).

The research was funded by the National Science Centre, Poland, under grant no. 2023/49/B/HS3/01529, and by the Universidad Católica de Santa María in Arequipa, Peru.

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