I love looking down the microscope at an artefact and seeing evidence for past use – whether it be micro-scarring along a tool edge, polish or striations that can only be seen under a microscope, or residues trapped in micro-crevices of a stone or smeared across a tool surface. For me, this is very exciting, and the best bit: it all means something! Apart from confirming that the artefact was indeed used, the specific pattern of the usewear, in combination with technological features of the stone and the presence (or absence) of residues, can provide information on how that tool may have been used in the past. Determining past tool function is highly important as it provides valuable insights into specific tasks, resource-use, and patterns of behaviour of various hominin groups.
Dr Ebbe Hayes looking down the microscope.
Who is the archaeologist from down under?
My name is Ebbe (aka Dr Elspeth Hayes) and I am an Australian-based archaeologist and researcher. I am the current Director of MicroTrace Archaeology, a company that specialises in the study of usewear and residue traces of various tool types and materials. Throughout my career, I have been lucky enough to study various assemblages of stone tools from many regions of the world. I started my PhD in 2011, looking at the function of grinding stones from the oldest site in Australia, Madjedbebe, which has evidence for human occupation from ~65,000 years ago. This extraordinary site presented with many exciting finds, including a large assemblage of grinding stones and fragments that became the focus of my PhD research. I wanted to determine how these tools were used—each tool had clear traces of use that indicated they were used for grinding, but what did these grinding stones grind? I used a range of microscopes to document use-wear and residue traces on the working surfaces, as well as various chemical methods for characterising residues, including gas chromatography mass spectroscopy (GCMS, a method used to characterise non-visible molecules), biochemical staining and other biochemical colourmetric tests. This approach led me to discover that the grinding stones at Madjedbebe were used for a diverse range of activities, including grinding starchy and non-starchy plant foods (some of which could be identified down to species level!), seeds, ochre, bone and opportunistically for pulverising small animals. Using this information, I was able to understand how grinding stone function changed over time to adapt to changes in climate, landscape and resource availability, from the earliest occupation of the site starting from 65,000 years ago right through to modern times!
Taking a residue extraction from an experimental grinding stone to look at surface residues under the microscope.
From grad student to graduate
For my post-doc, I looked at stone tool assemblages from two key sites: Liang Bua in Indonesia and Denisova Cave in Siberia. Liang Bua is a limestone cave located on the Indonesian island of Flores, which became world-famous when researchers discovered the first known skeletal remains of Homo floresiensis; a small sized human affectionately dubbed the “hobbit” after JRR Tolkien’s book of the same name. Geological dating of volcanic ash and calcite found directly above and below the fossils indicated that Homo floresiensis probably became extinct around 50,000 years ago—just before or at the time when Homo sapiens arrived in the region. We studied sets of stone flakes from Liang Bua (including those made by modern humans—Homo sapiens, and Homo floresiensis) to assess the technological and cognitive capabilities of these anatomically distinct hominin groups. This study involved multiple researchers with highly specialised skills for characterising residues and usewear. Analysis included the extraction of residues for GCMS analysis using multiple solvents in an ultrasonic bath; FTIR and Raman spectroscopy to characterise residues in situ (without extraction) on the stone tools; and a conventional usewear analysis involving multiple microscopes. Our study found that the flakes at Liang Bua were used for a range of tasks, but those from tools made and used by modern humans were more varied and included the processing of siliceous plants, possibly to soften plant stems for fibrecraft.
Left image: Archaeologists at work: The old MicroTrace team inside Liang Bua, taking portable FTIR readings of residues from stone tools excavated from the cave. L-R: Dr Suz Luong, Prof Linda Prinsloo; Dr. Luc Borde; Dr Elspeth Hayes (Photo by Richard Fullagar)
Right image: Use-polish and micro-scarring on the edge of a stone tool from Liang Bua taken at x200 magnification. The well-developed polish is typical for siliceous plant processing. Black scale bar is 1cm. White scale bars are 0.2mm.
The other site I worked on, Denisova Cave, is located in the Altai Mountains and is the oldest inhabited cave in Siberia with archaeological evidence spanning more than 300,000 years. The site became well known after the discovery of a small fragment of human fossil (the finger fragment of a 6- or 7-year-old girl) was found through genetic testing to belong to a previously unknown Homo species, a “Denisovan”. Following the same methods of analysis we used on the Liang Bua assemblage; our team studied a set of stone tools associated with the Middle Palaeolithic levels of the site. Using the Raman spectroscopy, we identified saturated and unsaturated fatty acids on at least eight of the stone tools in correlation with various usewear traces, specifically use-polish, striations, edge rounding and scarring, which indicated the micro-residues were likely associated with prehistoric tool contact with animal tissue. These results provide evidence for Middle Palaeolithic processing of animal tissue and probable skin scraping at Denisova Cave.
Looking at some of the stone tools from Denisova Cave at the museum in Novosibirsk with Honorary MicroTrace member Prof. Richard Fullagar (right).
From Graduate to Director
Since finishing up my post-doc in 2017, I have worked in various other labs (including the incredible TraceoLab at the University of Liege in Belgium) and looked at stone, bone and shell tools from various Australian and international sites. I started my own company in 2020, MicroTrace Archaeology, named after the lab at the University of Wollongong where my interest in archaeology blossomed into my passion. I keep busy with research and consultancy projects and running the MicroTrace social media pages. I also have two young boys who are wild but fun!: Billy (aged 4) and Jack (aged 2). If you love seeing images of microwear and residue traces, please follow our Instagram Account @microtracearchaeology and MicroTrace Archaeology facebook page, or visit our website www.mtrace.com.au
If you are interested in reading more about my research, follow my Research Gate Account https://www.researchgate.net/profile/Elspeth-Hayes – many of my papers are Open Access so free for you to download and enjoy!
Thanks for reading!
Ebbe xo
Further reading
Archaeology at Madjedbebe
(Hayes et al. 2022): https://www.nature.com/articles/s41598-022-15174-x.pdf
(Clarkson et al. 2017): https://hekyll.services.adelaide.edu.au/dspace/bitstream/2440/107043/2/hdl_107043.pdf
Stone tool use at Liang Bua
(Luong et al. 2019): https://www.nature.com/articles/s41598-019-53782-2.pdf
(Hayes et al. 2021): https://www.sciencedirect.com/science/article/pii/S2352409X21004119
Denisova Cave (Bordes et al. 2017):
Ebbe's latest research (Hayes 2024):
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