Paleofeces
Paleofeces (UK: Palaeofaeces) are ancient human feces, often found as part of archaeological excavations or surveys. Intact feces of ancient people may be found in caves in arid climates and in certain other locations. They are studied to determine the diet and health of the people who produced them through the analysis of seeds, small bones, and parasite eggs found inside. The feces can contain information about the person excreting the material as well as information about the material itself. They can also be chemically analyzed for more in-depth information on the individual who excreted them. The success rate of usable DNA extraction is very high in paleofeces, making it more reliable than skeletal DNA retrieval.[1]
The reason this analysis is possible at all is due to the digestive system not being entirely efficient, in the sense that not everything that passes through the digestive system is destroyed. Not all of the surviving material is recognizable, but some of it is. This material is generally the best indicator archaeologists can use to determine ancient diets, as no other part of the archaeological record is as direct an indicator.[2]
The process that preserves the feces in a way such that they can be analyzed later is called the Maillard reaction. This reaction creates a casing of sugar that preserves the feces from the elements. To extract and analyze the information contained within, researchers generally have to freeze the feces and grind it up into powder for analysis.[3]
The first example of researchers using paleofeces for the gathering of information occurred at Hinds Cave in Texas by Hendrik Polnar and his team. The fecal samples obtained were over 2,000 years old. From the samples, Polnar was able to gather DNA samples using the analysis methods recounted above. From his research Polnar found that the feces belonged to three Native Americans, based on mtDNA similarities to present day Native Americans. Polnar also found DNA evidence of the food they ate. There were samples of buckthorn, acorns, ocotillo, nightshade and wild tobacco. No visible remnants of these plants were able to be seen in the fecal matter. Along with the plant material, there were also DNA sequences belonging to animal species such as bighorn sheep and pronghorn antelope, both of which lack any evidence elsewhere in Hinds Cave, indicating that they were killed and consumed elsewhere.
This analysis of the diet was very helpful. Previously it was assumed that this population of Native Americans survived meagerly with berries being their main source of nutrients. From the paleofeces, it was determined that these assumptions were incorrect and in the approximately 2 days of food that are represented in a fecal sample, 2-4 animal species were represented and 4-8 plant species were represented. The nutritional diversity of this archaic human population was rather extraordinary.[4]
See also
References
- ^ A Molecular Analysis of Dietary Diversity for Three Archaic Native Americans. Hendrik N. Polnar et al. PNAS 10 April 2001: 98 (8) 4317-4322. [DOI 10.1073/pnas.061014798]
- ^ Feder, Kenneth L., Linking to the Past: A Brief Introduction to Archaeology. New York: Oxford University Press, 2008. Print.
- ^ Divining Diet and Disease From DNA. Erik Stokstad. Science 28 July 2000: 289 (5479), 530-531. [DOI:10.1126/science.289.5479.530]
- ^ A Molecular Analysis of Dietary Diversity for Three Archaic Native Americans. Hendrik N. Polnar et al. PNAS 10 April 2001: 98 (8) 4317-4322. [DOI 10.1073/pnas.061014798]