The Identi�cation of Fibers from a Mummy Bundle, Tarapaca Valley, Chile Tessa de Alarcon, Elizabeth Drolet, Robin O’Hern and Cindy Lee Scott

Professor Ioanna Kakoulli, Visiting Post-Doctoral Fellow Jenny Hallstrom and Sta� Research Associate Vanessa MurosUCLA/Getty Masters Program in the Conservation of Archaeological and Ethnographic Materials

Abstract

Analysis and Results

Conclusions

References Cited

Acknowledgements We would like to thank Vanessa Muros for her assistance locating literature as well as for her numerous demonstrations of sample preparation techniques. Thanks to Ioanna Kakoulli for providing us with the in-depth information on the context of the samples as well as for her contributions of additional reference materials and slides. We would also like to thank Professor Kym Faull for his assistance with identifying avenues of future research and analysis.

This study undertook to identify �ve �ber samples from a mummy bundle from Tarapaca 40, Chile by morphological and chemical characteristics. FT-IR was helpful only to distinguish between animal and plant �bers. It was determined that the �ve samples were animal. It would appear that the molecular vibrations of human hair and camelid wool are too similar to be di�erentiated. Based on hair morphology we were able to identify that:

TR40-L8-ESP0035-Sample 1 is likely camelid TR40-L8-ESP0035-Sample 2 is likely human TR40-L8-ESP0035-Sample 3 is likely camelid TR40-L8-ESP0035-Sample 4 is likely human TR40-L8-ESP0035-Sample 5 is is likely camelid.

The great variability of form for camelid �bers prevents us from making de�nitive identi�cations and the �bers would bene�t from further investigation.

SCALE CASTS

This photomicrograph of the scale cast from Sample 5 shows the distinctive mosaic pattern that enables us to identify this sample as a camelid �ber.

Scale casts of hair samples can provide important morphological information for the identi�cation of a �ber. Scale casts capture the surface arrangement of the scales. Scales are plate-like structures on the exterior of the hair shaft and make up the cuticle of the hair.

Human hairs always have an imbricate pattern. Animal hairs have a wide range of scale patterns and can vary from root to tip (Petraco and Kubic 2003).

Camelids can have a mosaic pattern that is distinct from human hair and an imbricate pattern which is similar to human hair (Appleyard 1978; Petraco and Kubic 2003).

Appleyard, H. (1978). Guide to the Identi�cation of Animal Fibers. Leeds, United Kingdom, Wira Leeds.Aguero, C. (2007). Textile Inventory/Technical Report. Tarapaca Valley Archaeological Project. Damiata, B. & Southon, J. (2009). Results of AMS Dating and Carbon Stable-Isotope Analysis of Charcoal and Organic Samples, Tarapaca Archaeological Project, Chile Tarapaca Valley Archaeological Project. Dransart, P. (1991). Llamas, Herders and the Exploitation of Raw Materials in the Atacama Desert. World archaeology 22:304-19.McCrone, W., McCrone, L. & Delly, J. (1978). Polarized light microscopy, Ann Arbor, MI, Science Publishers. No Author. (2002). Chapter 15 - Infrared Spectroscopy: Theory. Available at: http://orgchem.colorado.edu/hndbksupport/irtutor/IRtheory.pdf [Accessed November 30, 2009]Petraco, N. and T. Kubic (2003). Color Atlas and Manual of Microscopy for Criminalists, Chemists, and Conservators. New York, CRC Press.Silverman, H. & Isbell, W. (2008). Handbook of South American Archaeology, New York, Springer.

FOURIER TRANSFORM INFRARED SPECTROSCOPY

CROSS-SECTIONS

Fourier Transform Infrared Spectroscopy (FT-IR), is a useful tool for the identi�cation of organic and inorganic compounds based on their molecular vibrations when exposed to infrared radiation. These vibrations include symmetrical and asymmetrical stretching, bending and scissoring (Infrared Spectroscopy: Theory, 2002).

Cross sections of hair depict internal features and the shape of the �ber which can help with the identi�cation of unknown hairs. The shape of the cross section can vary in shape from round to oval to kidney bean shaped.

All hairs from the same person have the same cross-sectional shape. The shape of the cross section of an unknown human hair �ber can inform the viewer about the human’s ethnicity.

The cross sections of camelids vary because some hairs have no medulla, some have a single medulla and others a double medulla.

The images depict the cross-sections of Sample 3 (above) and Sample 1 (below). The samples appear to be camelid �bers. These images highlight the variability of cross-sectional shapes possible in camelid species. Both the size and shape are considerably di�erent, as are the type of medulla.

POLARIZED LIGHT MICROSCOPY In normal light, the waves of light vibrate in multiple directions. In polarized light, a �lter causes the light to vibrate in only a single direction. In plane-polarized light some optical features not visible in di�use light become apparent. Viewing materials under cross-polars enables theidenti�cation of isotropic and anisotropic materials (McCrone et al., 1978).

Individual �bers were removed from each sample and mounted in Cargille Meltmount with a refractive index of 1.539. The samples were examined using an Olympus BX51 polarized light microscope at 10x, 20x, and 50x magni�cation. Each sample was viewed with transmitted light, in both plane-polarized and crossed-polars, and all diagnostic optical features were noted.

The broken medulla and pigment distribution of Sample 2, which is likely human, are visible in the images to the left.

Sample 5, below, is a camelid �ber, which has a much thicker medulla and very di�erent pigment distribution than Sample 2.

Sample 2 under plane-polarized light (above).

FT-IR was used primarily to distinguish animal hairs from cellulose �bers. The presence or absence of amino acids in the spectra was used to di�erentiate between these two types of �bers.

Identifying the exact species from which the �bers originate was not so easily done. The expected peaks for camelid �bers are very similar to those for human hairs. There is not su�cient additional research currently existing to fully quantify and qualify the di�erences one might expect to see in trying to identify camelid wool from human hair or to distinguish between llama, alpaca, vicunia and guanaco.

Fiber samples from a formative period mummy bundle from Tarapaca 40 in the Atacama desert of Chile were examined in an attempt to identify them. Standards of human hair and alpaca were used for comparison. Fourier transform infrared spectroscopy (FT-IR) spectra were collected on the samples and standards. The morphology of the �bers and standards were examined using polarized light microscopy (PLM), scale casts and cross-sections. The spectra from the FT-IR analysis could not be used to di�erentiation between human and alpaca hair. Based on morphology, three samples were identi�ed as camelid and two were tentatively identi�ed as human.

Alpaca

Human Hair

Sample 2

Sample 4

Analysis and Results Continued

Sample 2 under cross-polarized light (above).

Sample 5 under plane-polarized light. Sample 5 under cross-polarized light.

Cross-sections of Sample 3 (above).

The mummy bundle from which the samples were taken. Image courtasy of the Tarapaca Valley Archaeological Project.

Cross-sections of Sample 1 (above) .