By Emily McCuistion
Howdy, you may have seen mention of me on this blog and on our facebook page but this is my first official post for the ASWT project. I introduced myself at the beginning of the season, but to refresh I am one of the three interns on the Eagle Nest Canyon 2015 Expedition. My previous archaeology work has been primarily with the National Park Service and Forest Service, neither of which generally have the resources to undertake studies such as this one. This is the first in-depth archaeological excavation I have worked on and I’ve been blown away by the site itself, the other expedition members and the leadership overseeing the project, and our numerous collaborators who contribute their specialized expertise on various and sundry sub-disciplines (chemistry, botany, entomology, geology…the list goes on). It seems that there are infinite directions that project-related studies could go. I love interdisciplinary research and so I’ve been especially taken with the subject on which I am blogging. These delicate resources contain a world of information inside them- I’m glad to introduce the coprolites of Eagle Cave!
The study of human coprolites, also known as paleofeces, palaeofaeces, or simply dried-up old poop, was not regarded as important by the archaeological community until the mid-20th century. Now we realize that we have a lot to learn from coprolites; they can inform us on past diets and ecosystems, the health of an individual, and the manner in which one ate and pooped. Archaeologists can look at the plant and animal macrofossils (visible undigested remains), tiny pollen grains, phytoliths (micro-structures created by plants), viruses, parasites, and even bugs found in coprolites! Further, coprolites can be directly radiocarbon dated (so we can determine how old they are) and they preserve not only the DNA of the person who made the deposit, but also the DNA of the animals and plants that were consumed. Though perhaps less revealing, shape, color and of course location of the deposit are relevant. The study of odor, though noted by many researchers, has as yet not proved of scientific value.
Though I hesitate to mention paleontology- the oft confused (with archaeology) but unrelated study of dinosaurs- the study of dinosaur coprolites pre-dates the study of human. We are indebted to paleontologists for first recognizing the potential in coprolite study. The word coprolite, derived from Greek, was termed in the 1830s by an English paleontologist and translates to “dung stone.” I have yet to hear about human coprolites that have turned to stone, nonetheless the use of the word coprolite to describe human feces in an archaeological context is pervasive.
The Lower Pecos Canyonlands is famous for its coprolite studies, specifically those conducted on specimens excavated from Hinds Cave. Coprolites have been identified at other sites in the region but none have been so well studied as those from Hinds.
Even knowing that coprolites preserve well in the Lower Pecos we didn’t really expect to find them in Eagle Cave – coprolites were not found during the 2014 field season in any of the shelters investigated in Eagle Nest Canyon. Happily, during our excavations this spring we were excited to find an abundance of well preserved coprolites! Thus far over 80 coprolite specimens have been inventoried during this field season, the vast majority of them excavated from near the front of the rockshelter and approximately a meter or two below the surface.
At Eagle Cave the coprolites are mainly found in areas of discarded fire-cracked rock and plant remains (See: Between a Rock and a Heart Place for info on the fire cracked rock in Eagle). Sometimes they are found within compacted and dry-cracked sediment which we hypothesize may be evidence of urine-soaking, and of which we are taking samples. Sometimes a coprolite is found near a smooth river cobble; speculations about wiping methods ensue…
Analysis of the coprolites is not yet underway but there are some basic observations that can be made about the Eagle Cave specimens. (We are assuming all the specimens we have collected are human; however, it should be noted that other animals have pooped in Eagle Cave over the preceding 9000 years and some of the specimens we have collected may not be human.)
Shape- It has been found that plump, shapely coprolites are often from a fiber/plant-heavy meal while the “loose” ones may be from an individual who had recently consumed a lot of meat. There are, however, many other reasons that one could have had fluid bowel movements: parasites, water containing algae-born toxins, plants with a laxative effect (sotol and lechuguilla – both baked in earth ovens – are known to have this effect on some people), even emotional states- fear has been cited- can cause diarrhea.
Size is affected by several conditions, including length of time since the last bowel movement and types of food eaten. Meals based on a single type of food can result in smaller stools, though a vegetarian diet can result in a larger stool than an omnivorous diet.
Color can be indicative of diet; the darker specimens often result from meat consumption while the lighter ones can be indicative of a vegetarian and/or carbohydrate-rich meal. When dried, however, colors change. Nonetheless, it is interesting to note color variations.
Macrobotanicals, bones and fur (Macrofossils): Botanists and faunal experts can identify large plant and animal remains within coprolites. Thorough analysis requires breaking down the coprolite and separating it into constituent parts, however, macrofossils are sometimes visible on the surface. Many thanks to our faunal and botanical associates- Christopher Jurgens, Haley Rush, Kevin Hanselka, Leslie Bush, and Phil Dering- for helping to tentatively identify bones and seeds in a couple specimens (meet our zooarcheology and archeobotany heros here: “Come Visit:” A Zoooarchaeologist Is Lured Back to the Lower Pecos and here:The Archaeobotanical Team Forms).
Insects: We have yet to see insects in the Eagle Cave coprolites (though a fly pupal case rolled out of a bagged specimen when I removed it for this photo shoot) but we sometimes see their bore-holes. In her 1978 dissertation on Hinds Cave coprolites, Glenna Williams-Dean reported that the experimental stools (a comparative collection of modern specimens left to dry in a rockshelter near Hinds Cave) were up to 95% consumed by insects! When conditions are not suited to an insect, especially a flying insect, it quickly moves on. For this reason they are good indicators of change in climactic and other conditions. (see: Archaeoentomology? for more details)
As mentioned previously, there are numerous other avenues for coprolite study (e.g., pollen, DNA/genetics, phytoliths, lipids, parasitism, general health, dietary nutrition, seasonality, medicine, food processing techniques, past environment, food trade/exchange, and food storage), but until we begin the analysis of the Eagle Cave specimens I cannot go into great detail. However, I can provide a brief synopsis (definitely not exhaustive) of some things archaeologists have learned from conducting coprolite studies in the Lower Pecos.
Let us start at the beginning of the digestive system: the mouth. A significant malady affecting ancient Lower Pecos people was dental wear and eventual complete toothlessness by their 40s. Danielson and Reinhard (1998) studied coprolites to examine possible causes for the dental wear and tooth loss in Archaic-age Lower Pecos skeletons. They considered several hypotheses, including that the grit from food-processing stones was wearing down the tooth enamel. Interestingly, they found no such grit in the coprolites they studied. Rather, calcium oxalate phytoliths (microscopic structures found in certain plants which pass unscathed through the digestive system) are found in abundance in Lower Pecos coprolites. They occur in the agave and cactus plant families (Agavaceae and Cactaceae respectively), and were found to be harder than tooth enamel. Not coincidentally, agave and cactus are a major part of the aboriginal diet of the Lower Pecos people. Other factors probably contributed to dental wear and loss, but a major cause was identified.
So, we have a population of largely toothless people who still must eat. But, must they chew? Specimen FN30984 from Eagle Cave, and some found at other sites, indicate there was not always much chewing – what Dr. Black charmingly calls the “grab it and gulp” method of eating.
That brings us to what they were ingesting. Certainly food availability varies with the seasons and the millennia, but there is coprolite evidence people were eating many of the same foods that are available today (e.g., sotol, lechuguilla, cattail, wild onion, prickly pear, insects, fish, deer, pronghorn, rodents, reptiles, bison [the kitchen ran out of that a few years ago], and too many other foods and medicinal plants to go into at this time – check out the TBH exhibit on the Ethnobotany of the Lower Pecos Canyonlands for more information about Lower Pecos diet. So far we have only been able to identify a few different seeds in the Eagle Cave coprolites but as we begin detailed analysis of the coprolites we will learn a great deal more.
Finally, when the meal is ready to be passed a decision has to be made on where to release the body’s effluent. I don’t know if there are enough sites in the region with mapped coprolite “deposits” to make assertions about latrine location preferences, but it was found that the latrine at Hinds Cave was at the back of the shelter. The vast majority of coprolites from Eagle Cave have been collected from near the front of the shelter at the top of the burned-rock-strewn talus slope.
For more discussion about coprolites from the Lower Pecos and Hinds Cave, check out the TBH exhibit on Hinds Cave to learn more. So much more on coprolites could (and will) be written, but right now other doodies call!
Danielson, Dennis R. and Karl J. Reinhard 1998 Human dental microwear caused by calcium oxalate phytoliths in prehistoric diet of the lower Pecos region, Texas. American Journal of Physical Anthropology 107: 297-304.
Williams-Dean, Glenna 1978 Ethnobotany and cultural ecology of prehistoric man of southwest Texas. Ph.D. Dissertation, Department of Anthropology, Texas A&M University, College Station.