Archaeobotany is a subfield of archaeology that seeks to better understand human-plant interactions throughout history by studying ancient plant remains. Studying Paleolithic archaeobotanical remains (the Paleolithic spanning 2.5 million years ago to 10,000 years ago) can reveal a wealth of information about human behavior and ancient environments. We can learn about ancient human plant-foraging and processing behavior, reconstruct paleodiets, and model ancient climates and environments. The field of Paleolithic archaeobotany is a relatively new and continually developing field. However, there are two limitations to this type of work that often go hand in hand: because organic material can decay over time, it is rare for botanical evidence to be preserved at Paleolithic sites, and thus many archaeologists focus instead on the collection and study of other (more durable) artifact types, such as stone tools.
Mughr el-Hamamah (MHM), a cave located in northwestern Jordan, is one of the few Paleolithic sites in the Levant with an abundant assemblage of well-preserved macrobotanical remains. Macrobotanical remains refer to those that are relatively large and can be seen by eye, like seeds, as opposed to microbotanical remains like pollen grains. MHM was occupied between 44,000 and 34,000 years ago by early anatomically modern humans (Homo sapiens). The macrobotanical assemblage consists of tens of thousands of carbonized (burned) wood charcoal, seeds, and nutshell fragments. Most of these remains were associated with combustion features/hearth deposits used for cooking or heating purposes inside the cave. The botanical remains are currently being studied as part of an ongoing research project to examine how residents living inside the cave gathered plants and utilized wood resources from their local environment.
|As a Penn Museum Fellow, I spent the past academic year conducting a methods-based study on the wood macrobotanical remains from MHM (this research was also the focus of my senior thesis in Earth Science). My project attempted to determine which of two common macrobotanical recovery methods – flotation or dry-sieving – is most effective at retrieving carbonized wood remains. In doing so, I hoped to shed light on the best practices in Paleolithic archaeobotany and to make recommendations for archaeologists working on Paleolithic sites going forward.
During the fall 2020 semester, I spent much of my time in the Archaeobotany Lab at the Center for the Analysis of Archaeological Materials (CAAM) at the Penn Museum carrying out this research. I examined and quantified 16 high-priority samples containing carbonized wood charcoal, designated as such due to their association with well-preserved archaeological contexts in the cave. This microscopic work involved sorting, counting, and weighing the thousands of wood charcoal specimens from these 16 samples. While I did so, my mentor, Dr. Chantel White, collected similar data on only the most well-preserved specimens – those that were free of phosphatized ash concretions.
After quantifying these specimens, I compared the density of wood that was retrieved from flotation versus the density that was recovered via dry-sieving. In total, over 12,000 wood specimens were included in my study. The result was deeply intriguing, unexpected, and puzzling – a different recovery technique was more effective depending on whether I was looking at the overall densities of the wood assemblage or if I was looking at the densities of solely the most well-preserved specimens. Dry-sieving was most effective at recovering total charcoal in terms of overall numbers, while flotation was most effective at recovering concretion-free specimens.
Further research will be needed to determine the cause of this result. In the meantime, I can make recommendations for future Paleolithic archaeobotanists based on this research project. I recommend that a different recovery technique is undertaken depending on the archaeologists’ recovery goal. If the team is primarily concerned with bulk recovery, dry-sieving will be the most preferable method of retrieving archaeobotanical remains. If the archaeologists are seeking remains that are most well-preserved for taxonomic identification purposes, flotation may be the best method to employ.
In conducting this project, I learned so much about the field of archaeobotany, conducting archaeobotanical research, and the importance of studying specific field recovery methods. I also hope I have shed some light on the varying effectiveness of flotation and dry-sieving recovery techniques, and that my work marks the beginning of studies on best practices in Paleolithic archaeobotany, as this is a field that contains immense and ripe opportunity to explore human prehistory.
Aria Spalding is a recent graduate of the College of Arts and Sciences majoring in Earth Science with minors in Anthropology and Archaeological Science. She was one of three Penn Museum Fellows selected for the 2020-2021 academic year. The Penn Museum Fellows program provides financial and research support to three Penn undergraduates as they complete a capstone project or thesis that articulates with the Penn Museum’s collections, archives, galleries, or broader mission.