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Accueil > Programmes > Collaborations internationales

Programme ECOS-Sud - CONICYT (2010-2012)

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Physical-chemical characterisation of nano-cosmetics employed on the Chinchorro mummies from the extreme north of Chile

The development of scientific archaeology during the last forty years has brought along a revision of both the theoretical setting and the analytical methodologies accompanying the processing and interpretation of the vestiges of the past. One of the main changes within the methodological realm has been the fostering of interdisciplinary research, with the consequent contribution of techniques and methods from other disciplines towards solving archaeological problems. Over the past few decades in Chile, the use of physical-chemical techniques for the characterization of archaeological materials has notoriously contributed to the understanding of technologies developed and employed by pre-Hispanic populations.

Following this trend, the ECOS-CONICYT project “Physical-chemical characterisation of nano-cosmetics employed on the Chinchorro mummies from the extreme north of Chile” has sought to contribute to the study of the Chinchorro culture – a fisher-hunter-gatherer society inhabiting the south of Perú and the north of Chile during the archaic period (5.000-2.000 BC). These groups developed a lifestyle specialised in the exploitation of marine resources, with the introduction of significant technological innovations.

In addition to these developments, the Chinchorro culture had very particular funerary practices involving complex mummification techniques considered today as the oldest in the world. These techniques are particularly complex and varied, but they all stem from a common element : fleshless bodies “reassembled” through the use of twigs, clay and pigments. After the reassembly process, the bodies are meticulously remodelled, emphasizing the features of the face and some of the organs, adding wigs, and painting the body using mainly black and red pigments. A whole categorisation of mummies springs from the variety of techniques applied to the above process and, taking interest in this variety, our project has sought to contribute to the identification of the different elements and compounds used within the context of these techniques. We have specifically sought to define and characterise the presence of complex preparations of the mummies, and to specify the factors and agents influencing their conservation, particularly the preservation and alteration processes applied to the skin and hair.

In order to achieve the characterisation of the elements of these compounds, we established an analytical protocol considering the use and combination of different physical-chemical techniques for inorganic as well as organic components. In this process, we chose to perform non-destructive method of analysis for the reproduction of results and exposure of a single sample to all the different analyses involved.

The collection of samples from mummified bodies took place in the labs at the San Miguel de Azapa Museum of the University of Tarapacá (Arica, Chile). These samples were then packed and taken to the laboratories of the Centre de Recherche et de Restauration des Musées in France where each of them were observed in turn under a binocular magnifying glass at different degrees, and a Scanning Electron Microscope (SEM). Afterwards, their basic elements were analysed through an Energy Dispersion Spectrometer (EDS) coupled to the SEM. Finally, we used a portable X-Ray micro-diffraction portable, contributing to the structural characterisation of the minerals employed during the mummification process.

The results obtained until now contribute highly in confirming the complexity of the Chinchorro mummification techniques due to the presence of a whole array of materials in the production process : materials both inorganic (clay and pigments) and organic (skin), visible to the bare eye and arranged in several layers covering the bone structure were differentiated from one another according to their microscopic composition. However, additional to the elemental characterisation of the clays and pigments employed, we also analyse into their structural analysis. With all the analytic techniques used, we were able to specify the kind of minerals used to achieve the red (iron-based minerals) and black (manganese-based minerals) colouring of the mummies, and, in some cases, we identified the use of certain copper-based minerals, which is a particularly interesting find in such ancient records. Overall, the recurrent identification of these materials indicates a deliberate choice, a specialised knowledge of raw materials and their localisation, extraction and preparation, as well as the production and achievement of particular colours. Likewise, we identified the superposition of several layers of differently composed paints, accounting for retouching or repainting of the bodies.

As one of the aims of the project was to contribute to the understanding of the particular damage affecting some of the mummies and its connection with the higher level of humidity in the region of their discovery, we carried out a skin analysis with different techniques such as solubility tests, confocal microscopy observation, infrared spectrometry, and secondary ion mass spectrometry. However, before we could start on any of these analyses, one of the main challenges was to achieve the required thinness of the cuts on samples previously embedded in resin – a process named ultramicrotomy. The results obtained indicate a degradation of the dermis layer, particularly when it comes to the amino acids and protein fragments. However, we are now in the process of identifying the causes of this so that we may confirm whether they originate from chemical or microbiologic factors.

Consequently, at a methodological level, this project has allowed us to define and share analysis protocols specifically for particularly fragile archaeological samples. At an interpretative level and from an interdisciplinary approach, the development of this project contributes to a greater understanding of the knowledge and technology developped by these remote coastal societies in the mummification of their deceased. Finally, the results obtained will provide grounds for better conservation of the Chinchorro mummies kept at the San Miguel de Azapa Museum at Universidad de Tarapacá.

Text published in the Conicyt international relation journal 17

Lead researchers :

-  Chile : Dr. Marcela Sepúlveda, Anthropology Department, University of Tarapacá.
-  France : Dr. Philippe Walter, LAMS (Laboratoire d’Archéologie Moléculaire et Structurale), Université Pierre et Marie Curie.

Co- researchers :

-  Chile : Dr. Vivien Standen, Anthropology Department, University of Tarapacá ; Dr. Bernardo Arriaza, IAI, University of Tarapacá ; Dr. Calogero Santoro, IAI, University of Tarapacá - CIHDE.
-  France : Ms Elsa Van Elslande, LAMS, Université Pierre et Marie Curie.