Digging up the Truth: Studying Ancient West Mexican House Models

This is a guest post by Bianca Poma, a 2020 Hispanic Association of Colleges and Universities Archaeological Research Fellow at the Library of Congress. Bianca is an Anthropology major at the University of Florida and is working with the rare West Mexican House Models that are part of the Jay I. Kislak Collection of the Archaeology and History of the Early Americas.

Since the moment I could carry on a well phrased conversation, I have always been curious by nature and have asked a lot of questions throughout my life. I believe this curiosity has led me to the ultimate career opportunity here at the Library of Congress. Throughout my life, mentorship has played a critical role in defining who I am professionally and personally. I couldn’t feel more blessed for the opportunity to now be mentored by John Hessler himself, curator of the Jay I. Kislak Collection of the Archaeology and History of the Early Americas at the Library of Congress, housing over 3500 historical artifacts that have been researched by prominent scholars around the world.

From a young age, I had the privilege of being in touch with my Peruvian roots, more specifically, my mother deriving from the Huari culture and my father from the Chavin culture. Raised by two examples of integrity and resilience, my greatest inheritance of all was their commitment to making sure I knew where I came from. Sitting and embracing the ruins of Machu Picchu, Ahlambra, Nazca Lines, Inkawasi, Pyramids of Teotihuacan, and the deep and complex cultural traditions of the communities there made me realize how important it is to recognize the potential and capacities humans can have in such diverse domains.

Prior to coming to the Library, I had the privilege to work on an innovative gene therapy to help combat autoimmune diseases at the University of Florida’s College of Medicine under Dr. Brad Hoffman. From developing a sharp eye for detail to improving upon scientific inquiry and methodology, I was able to gain the skills to take on the challenges as an Archeological Research Fellow working with the Kislak Collection here at the Library.

Large -two-tiered house model with fifteen inhabitants, West Mexico, 200BCE-300CE. Painted Red Ceramic, Jay I. Kislak Collection, Geography and Map Division, Library of Congress.

From the first day I reported to the Geography and Map Division, I was given the chance to handle and study up close the pre-Columbian artifacts that makeup the Kislak Collection. Of the many valuable artifacts, there is an exceptional and particular collection that caught my eye, made up of examples of rare West Mexican House Models, dating around 200 BCE – 300 CE. These house models are typically discovered in larger archaeological finds, buried in shaft tombs 10 to 50 feet deep!

West Mexican House Model, 200 BCE-CE 300, Jay I. Kislak Collection. The dwelling is enclosed on three sides, with another partition covering one-third of the front. Inside, three seated figures eat from a large central bowl, while their dog looks on.

The Ancient West Mexicans were a culture that predates both the most advanced Aztec and Maya civilizations. For more than a century,  this art has been highly valued and desired for its captivating view of three-dimensional human forms representing everyday activities and rituals and depicted in an architectural setting.  In the early 20^th century, these artifacts were highly prized and even collected by artists such as Frida Kahlo and Diego Rivera. Unfortunately, with the rise in the value of these objects, the increase of foul-play goes up as well, as it becomes an opportunity for elicit looting and forgery. Imitations of these pieces of art and the looting of tombs have significantly limited the amount of knowledge researchers can acquire from this ancient civilization.

One method in determining the authenticity of these pieces comes from identifying the remnants left by necrophilous, better known as corpse eating insects, and metal oxidizing bacterial colonies that thrive in the perfect micro-environment of the tombs below ground. These organisms leave behind patterned black marks along with remnants of their pupae that become mineralized and that have survived for over two thousand years!

Microscopic Image of Mineralized Bacterial Residue. Photograph by Bianca Poma, Library of Congress.

These mineralized stains appear on the exterior surface of the artifacts and have a dendritic-like structure, branching off into many directions. Bacteria such as Metallogenium and Leptothrix discophora both feed on trace metals, mainly manganese and iron, provided by the surface water dripping into the tombs and onto the artifacts, and deposit the oxidized remains of these metals as their colonies grow. L. discophora has a more distinguished stain; rather than a simple dark charcoal colored mark, it has the appearance of a polished surface. Using a digital microscope, I was able to located these patterns on many of the West Mexican House models in the Library of Congress collections.

Microscopic Image of Mineralized Bacterial Residue that might have been left by Leptotrix discophora. Photographed by Bianca Poma, Library of Congress.

We now live in such a promising time with technology allowing us to uncover many hidden secrets that could not have been revealed or accurately studied just 20 years ago!  In the past few decades, a strong movement in applying nondestructive methods and imaging has yielded important results in archaeology and other forensic sciences. The digital imaging and microscope work I am doing here will serve as a basis for research to actually identify the composition of the stains on the West Mexican artifacts in the near future.

Working at the Library of Congress has fostered my drive to continue serving my community by applying new technology and the sciences as an Archaeological Research Fellow. Throughout my initial few weeks here, the ability to collaborate with such an influential community has broadened my perspective and knowledge within and outside of my field, through meeting other scholars, researchers and curators. As an anthropologist, to know these archaeological artifacts that I hold in my hands were once held over 2,000 years ago, fills me with wonder. As a biological researcher, I can’t help but be amazed at the resilience of puparial remnants, mineralized in the deep past, and waiting to be appreciated 2,000 years later!