X-rays are a part of life — you get them when you’re at the dentist, when your bag goes through security at the airport, or when you visit the doctors for a broken bone. But what if I told you that they are now becoming a part of death as well? Scientists have been using a method called X-ray fluorescence (XRF) to analyze Egyptian mummy wrappings to better understand the past.
To first give a sense of what X-rays are, they’re a type of radiation in the electromagnetic spectrum between gamma rays (which are the smallest and the most energy packed) and the visible light spectrum (the light that you and I can see). X-ray fluorescence essentially shoots a beam of X-rays at the sample, which in turn gives off its own unique set of fluorescent X-rays. Those can be used to identify the sample’s elemental composition and highlight patterns or words that aren’t visible to the naked eye — which is where the mummies come in.
Roman and Greek inscriptions highlighted by XRF
Ancient Egyptians used to layer old, previously-written-on papyrus with plaster to create their mummies, but until just recently, it was impossible to discern what was written on them. It’s like trying to read an article from a newspaper transformed into an aged, multi-layered paper mache object. The liquid in the plaster fades the ink and thins the paper. The layers of paper oriented in all different directions make it nearly impossible to see what was written below the surface. However, XRF (and other X-ray imaging techniques) solves many of these problems. To start, scientists determine the composition of the papyrus to distinguish it from an element in the ink — such as iron or bromine. They can then detect and highlight the ink using these X-ray techniques.
Testing a mummy head at the Lawrence Berkeley Lab to find non-destructive technologies that reveal the hidden writings
One of the advantages of this type of technology is that it’s non-destructive, meaning that this would hopefully deter people from submerging the papyrus in water or resulting to other destructive techniques to try to uncover the message. As of right now, scientists are still perfecting the imaging software, but some preliminary tests have discovered what some people of the ancient past used to write about. Joshua Sosin, a member of this project from Duke University, said, “We have hate mail, the strange diary ramblings of a hypochondriac, contracts and bills of sale.” The more writing we can uncover, the more we can understand the people who had ordinary lives and thus better understand the society they lived in (as opposed to mainly using historical text from influential writers or people publicly displaying their thoughts).
While some scientists are focusing on this technique for mummies, it could be applied to carvings in ancient pottery, discovering the layers of a painted vessel, or relatively dating an object (through elemental analysis using XRF) (see additional readings below). X-ray technologies open up a new method of analyzing artifacts that uncovers information that we previously thought was lost.
Sources:
http://www.sciencealert.com/archaeologists-are-using-x-rays-to-read-inside-mummy-coffins
https://www.wired.com/2016/10/x-rays-revealing-mysterious-writings-mummy-coffins/
https://www.thermofisher.com/us/en/home/industrial/spectroscopy-elemental-isotope-analysis/spectroscopy-elemental-isotope-analysis-learning-center/elemental-analysis-information/xrf-technology.html
Image sources:
http://www.bbc.com/news/science-environment-12820302
https://www.wired.com/2016/10/x-rays-revealing-mysterious-writings-mummy-coffins/
Additional readings:
http://www.bbc.com/news/science-environment-12820302
https://phys.org/news/2016-10-x-rays-uncover-techniques-creation-art.html
In a recent article, archaeologist outline some issues with XRF and ask for a new approach to be taken place. What is your take on these six assumptions outlined by these archaeologists?
Pollard, A Mark; Bray, Peter J; Gosden, Chris. 2014 Is there something missing in scientific provenance studies of prehistoric artefacts? Antiquity88.340: 625-631.
This article doesn’t really refer negatively to XRF except vaguely with having to do with absolute dating, as my blog post was mainly concerned with reading layered text. However, I believe that adding to the sixth assumption helps with better understanding an artifact’s history. They mention the importance of noting the amount of time it takes to get from point A to B and how sometimes, it isn’t always instantaneous (where looking into the past, 1,000 may be considered instantaneous). Therefore, an archaeologist should see if an object was transported from A to B by trade or by something else (as if the time isn’t instantaneous, then it’s probably not indicative of trade).
The article mentioned how in attempting to do so, there are some issues with dating (such as radiocarbon dating and the kiln example of the date not being the age of the kiln but rather the last firing). They’re looking to find a trace of the movement between A to B, with each stage leaving a mark. For certain objects such as the tabua, there’s a change in color in the teeth as it passes from person to person or other “shifts in color and surface wear” that can help determine relative assembly chronologies. It also mentioned internal clocks and how manipulating an object (such as copper) could leave compositional changes that would be indicative of its age. Without utilizing this information, archaeologists are missing out on key information that help them to better understand their artifact and thus its implications within the society.
The other assumptions deal with tracing an object from its source and allow for vital assumptions to be made in order to analyze and draw conclusions about the artifacts. While some appear to be obvious, stating these allows the archaeologists to work with the same basic assumptions. Adding to the sixth encourages investigation of space and time to understand the movement of an artifact and those implications, which appears to be much needed for a more comprehensive understanding of an artifact.