The MetaboloMips group of the University of the Basque Country (EHU) has applied experimental archaeology to detect lanolin in prehistoric tools
The MetaboloMips group applied experimental archaeology to find out whether lanolin (a wax usually found in wool) was present on prehistoric tools made of flint and obsidian as that would indicate that the humans of that time sheared their sheep, and thus reveal when textile making started. The analytical strategy developed by the EHU will enable degradation compounds of lanolin to be detected in archaeological samples.
Archaeologists do not have clear evidence as to when prehistoric humans started shearing sheep, nor when early textile making began. One of the main theories in this regard is that it began during the Neolithic period, when tools made of flint, bone or stone were used rather than ones made of metal. In an attempt to clarify this, archaeologists from the Institute of Human Palaeoecology and Social Evolution (IPHES) of Catalonia approached the EHU’s MetaboloMips group enquiring whether it would be possible to find some biomarkers that could provide evidence that humans at that time sheared sheep using flint and obsidian (materials from the time).
Lanolin is a natural wax present in wool and forms to protect the sheep’s hide and wool from the environment and accumulates on the tools used to shear the sheep. Because it is a complex blend of esters, alcohols, fatty acids and hydrocarbons, it is quite difficult to characterize lanolin chemically. “We saw that traces of lanolin left on the tools used for cutting the fleece degrade over time; the main compounds of lanolin disappear and, in the process, new compounds are formed,” said Asier Vallejo, a researcher in the MetaboloMips group.
Experimental archaeology has long been applied to find out how lanolin that has been degraded by light and moisture can be detected: “We sheared sheep using flint and obsidian tools created today, and put the tools in a degradation chamber to simulate the degradation that occurs over the years so that we could see which compounds or biomarkers are stable and which new compounds are produced. We also had to look for ways of detecting these derivative compounds in such small amounts,” explained the analytical chemist.
The next step: testing the methodology on ancient tools
Now, the goal is to apply this methodology to actual archaeological tools to “find out whether traces of prehistoric lanolin are present.” As Vallejo pointed out, “this methodology is important for archaeologists, as they have no evidence whatsoever as to the period during which textile making began”. Nowadays, the fleece is mainly cut to deworm the sheep and prepare them for the summer, but at one time the wool was worn as well. It is thought that sheep shearing may have begun during the Neolithic period. “So, if, firstly, lanolin was found to be present on the flint tools (i.e., if it is known that the sheep were shorn) and, secondly, if awls and similar tools appeared in the vicinity of the ones used for this purpose, that would confirm that this was the beginning of textile making.”
Vallejo admitted that a huge piece of interdisciplinary work had been done: “We integrated the ideas and ways of working of various groups, as well as different techniques.” Indeed, the researchers first tried to use types of analysis that do not destroy traces of samples (molecular spectroscopy), but were unable to guarantee the results. So, they had to propose a destructive methodology to analyse the samples (gas chromatography and mass spectrometry). “This means that by conducting analyses to see whether there were traces of lanolin on the prehistoric flint tools, these traces were going to disappear,” he said. In any case, this research has achieved an effective analytical strategy and has opened the doors to new lines of research in applied analytical chemistry.
Additional information
This research was carried out by the MetaboloMips group of the EHU’s Faculty of Pharmacy in collaboration with the EHU’s IBeA group and the Institute of Human Palaeoecology and Social Evolution of Catalonia (IPHES) and the University of Palermo. The MetaboloMips research group of the EHU and the IPHES institute have a long history of collaboration.
Dr Asier Vallejo lectures in the Department of Analytical Chemistry of the EHU’s Faculty of Pharmacy; he is a lecturer on the Environmental Sciences Degree course and on the Master's in Forensic Analysis.