Science Dialogues: New Online Magazine for Integrating Science

Check out my post to Science Dialogues, a new online magazine dedicated to integrating science in the modern world by facilitating and fostering intellectual ties and friendships across disciplinary boundaries: http://sciencedialogues.com/?p=1593.

In the post I mention my recently defended Ph.D. dissertation (which was accepted by the UIC Grad College last week following their final review of formatting!) as well as my upcoming project–more on the latter to come. For now here is a sneak peak at the possible next site…

A General View of Caballete

Floor Stains and Ancient Ales

What do floor stains and ancient ales have in common? Well, archaeologists use similar techniques when analyzing residues on ancient surfaces or reconstructing prehistoric beer recipes.

Recently I decided to do some exploratory data analysis using the leftover floor samples I had from the XRF analysis. The idea is to test the floors to see if I can identify some of the biological components of the burnt offerings (e.g. plant species, fish, shellfish, guinea pig–oh, the humanity!).

Enter Fourier Transform Infrared (FTIR) spectrometry. FTIR uses infrared spectroscopy to reveal how compounds adhere to artifacts or surfaces, including organic residues from plants and animals. These signatures can then be compared to known examples in order to identify what types of organic materials were associated with the artifacts or features.

For my exploratory experiment I dissolved 1 cc of a single floor sample in 1 cc each of  hexane, amyl acetate, xylene, and de-ionized water. I spun those in a centrifuge so that the homogeneous floor sample settled to the bottom of the test tube. I then piped out the solvent and put it on a depression of aluminum foil. The last step was the most exciting–I waited for the solvent to evaporate. It was literally like watching water dry. The first three solvents dissolved within 30 minutes, but the de-ionized water took much longer.

Solvents are used to dissolve the compounds. Here you see all of the materials used in the preliminary steps of FTIR analysis.

With the help of Field Museum conservator and science guru, JP Brown (he’s also largely responsible for the CT mummy scanning project), we identified a few particulates in the xylene mixture that may be something. At this point it is too difficult to tell. Unfortunately the amount of residue that remained is probably too small for FTIR but we may be able to use a powerful microscope to identify the material.

JP Brown looking at possible organic compounds under a microscope.

We’ve called in another expert who just so happens to be a volunteer at the Field Museum, Dick Bisbing. Dick served The McCrone Group for 25 years as Executive Vice President and Director of Services at McCrone Associates. He specializes in ultra-microanalysis and microscopy for a variety of real-world problems including criminal cases. In other words, he’s like a cross between Bill Nye the Science Guy and CSI.

Stay tuned…

Using Modern Technology to Reconstruct Ancient Ritual

Ceremonial structures like the 5,000-year-old temples I have been investigating at Huaricanga are marvels to behold. Often such buildings are well-maintained and represent the dedicated effort of ancient individuals who invested considerable time and materials in their construction. Walls and doorways tend to have elaborate decorations as well. When discovered, temples and churches receive quite a bit of attention from public media. For the field archaeologist, however, ceremonial architecture can be a pain in the butt. By its very nature, religious structures tend to lack any evidence of the activities that took place within them. Consider, for example, a contemporary church. Indeed it would be quite unusual to see domestic trash inside the walls of a place of worship. Culturally specific norms of sacred purity tend to forbid the accumulation of “unclean” remains within holy spaces resulting in a lack of artifacts in ceremonial contexts. Unfortunately, archaeologists rely on trash to interpret the past. Therefore, archaeologists need unconventional methods to reconstruct ancient ritual activities.

It’s not really as hard as it looks!

Modern scientific techniques available at the Field Museum can remedy the situation. The Huaricanga Archaeological Research Project (HARP) is one of the first projects in the Andes to utilize X-Ray Fluorescence (XRF) to reconstruct ancient religious rituals. XRF involves the use of X-Rays to penetrate a substance and excite the electrons within it. This electron “excitement” can be measured in parts per million for individual elements. XRF is often used to source ceramics or volcanic glass as individual clay or obsidian sources will have their own particular elemental signatures. This technique of measuring signatures can also be applied to archaeological surfaces.

All human activities leave residues. Take, for example, a coffee stain. Although you may be able to wash out the chai latte from your shirt, that liquid still leaves a material trace, a change in the elemental composition of the shirt that cannot be erased. This trace, however, can be detected using XRF.

During my archaeological fieldwork last year, I sampled a variety of temple floors for XRF analysis. This involved systematically scrapping off the uppermost layers of each floor with a clean trowel every 50 cm. Samples were taken across a single surface and between surfaces in order to look at rituals synchronically and diachronically. The bits of floor were placed in small baggies, labeled, and exported to the U.S. for analysis.

All that collecting XRF samples from ceremonial floors in the sun seemed to have turned my skin as red as my t-shirt.

With the help of Elise Blindauer (an undergraduate at the University of Illinois-Urbana/Champaign, see picture below), I was able to analyze over 200 samples using the XRF device at the Field Museum’s Elemental Analysis Facility. Raw results were statistically cleaned and then separated according to their sampling location on the floor (GPS coordinates were taken with a Total Station). Elemental enrichment levels were coupled with their locations and plotted using GIS to create maps per element.

Elise helping out with the XRF.

While it is obvious that the elemental concentrations are not consistent across single surfaces or over time, what these maps ultimately mean is a bit tricky. Since this is a new technique, interpretation is difficult. In Aztec temples, for example, areas with a high concentration of iron suggest that animals were sacrificed there since iron is a major component of blood. Other archaeological projects have clearly associated phosphorous with the use of plant remains. At Huaricanga, such interpretations will take time, but such is the difficulty in using cutting edge technology. Please see the HARP Results page for more information and exciting new finds!

2012 in Review

Happy New Year everyone! As 2012 draws to a close, I just wanted to thank you all once again for your support. HARP has been a huge success. Although the fieldwork has come to an end I have tons of analysis to do (not to mention writing that little paper I call a thesis…haha!). This website will continue to be up and running throughout the duration of this process and I will be updating it significantly within the month of January 2013. In the meanwhile, the WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

600 people reached the top of Mt. Everest in 2012. This blog got about 7,000 views in 2012. If every person who reached the top of Mt. Everest viewed this blog, it would have taken 12 years to get that many views.

Click here to see the complete report.

Huffington Post Blog Entry: Ritual is Power

Please check out my recent blog post sponsored by the American Anthropological Association on the October 24, 2012 edition of The Huffington Post. The brief entry discusses religion’s role in contemporary society and the possible evolutionary roots to its existence in human culture.

http://www.huffingtonpost.com/american-anthropological-association/ritual-is-power-religion-as-a-revolutionary-concept-or-an-evolutionary-advantage_b_1973622.html

In the near future I hope to explore the evolutionary advantages of ritual. Using my current fieldwork at Huaricanga as an example I hope to evaluate the impact of religious activities on human behavior to answer very basic anthropological questions.

Making Micromorphology “Cheese”

Archaeology is a fantastic field because of all of the interesting methodologies that we can use to reconstruct the past. For example, archaeologists use satellite imagery to see buried walls, radar to detect sunken tombs, and X-rays to reveal where ancient pottery makers obtained their clay. Similarly, we at HARP are using modern technology to tell us more about prehistoric Peru.

Micromorphology is the study of sediments with the use of a petrographic, or polarizing light microscope. The technique was first developed in the soil sciences in the 1930s and is now widely used in archaeology throughout the globe. Micromorphology has allowed researchers to reconstruct the natural and human processes responsible for the formation of archaeological sites. With the help of Dr. Paul Goldberg (Boston University), we’re using micromorphology to understand the construction activities that built the temples at Huaricanga and to learn more about the types of activities that took place on the floors that were ritually cleaned (and thus left no traces visible to the naked eye).

The process of taking a micromorphology sample is simple in principle, but sometimes difficult in practice.

1. Choose an appropriate place to sample. Often large profiles are sampled to obtain a series of floors, burning events, construction fills, etc. We targeted an area in the middle of the room that has a series of superimposed floors with fills in between them.
   

   Selecting a sample location was difficult because of the possibility of hitting hidden rocks that would be hard to wrap.

2. Remove a block of sediment that measures approximately 8 cm x 10 cm x 12 cm.A column of sediment is essentially pedestaled for sampling. In our case we cut an area that was a bit wider to allow us to pass the wrappings around the block. Since the floors are plastered and thus hard, we used a sharpened trowel as a chisel and hammered down through the different levels.
   

   Lucho and Carlos hammering out a block of sediment. One person hammered while the other maintained the integrity of the block.

3. Wrap the sediment block tightly. We used plaster bandages like those used to support broken limbs. Although the plaster dust was a bit messy, the plaster ensures that the loosest sediments stay intact. An intact sample ensures a better block to read the microstratigraphy. Alternatives to plaster bandages include toilet paper and packing tape as well as metal boxes used to cut out blocks. In the end, the sample looks a lot like a block of fresh cheese!
4. Once dry, the sample is exported to the United States where it is impregnated with resin, cut into microscopic thin sections, and analyzed under a microscope.

The results from this analysis will provide another line of evidence to reconstruct the 5,000-year-old rituals that took place at Huaricanga…Stay tuned!