Throughout time, mankind has had a fascination with uncovering lost treasures and artifacts of the past. Artifacts like the Rosetta Stone, the Olmec heads, and the sarcophagi of King Tut draw millions from around the world to marvel at the many wonders of the past. However, behind the glitz and glamor of these famous pieces lie complex scientific techniques that archaeologists employ in order to procure and study artifacts. Many of these techniques are used by researchers to further our knowledge of the past. Advancements in these technologies can lead to an immense future for the field of archaeology.
Possibly the most well known of the scientific techniques in archaeology is radiocarbon dating (Brunner et. al, 2020) Devised by Willard Libby in the 1940s, this technique revolves around the premise of the carbon-14 isotope being ubiquitous in organic matter. Radiocarbon dating works because of the large amount of carbon-14 in the Earth’s atmosphere. It is incorporated into Carbon dioxide that plants then take in as part of photosynthesis and the organisms that eat the plants eventually end up taking up the carbon-14. Over time, carbon-14 decays into the more stable isotope carbon-12, and the ratio of carbon-12 to carbon-14 indicates the age of the sample. To measure the carbon-12 to carbon-14 ratio, accelerator mass spectrometry is used. This procedure involves removing C – ions from a sample, removing electrons to give them positive charges, observing how many ions emerge in each jet, separated by isotope. The half-life of carbon-14, around 5,700 years, allows for the dating of organic samples up to 50,000 years old. Novel investigation into the uses of carbon-14 dating has explored the possibility of dating organic pigments and colors found at dig sites to produce an accurate dating, although the feasibility of converting the pigments to a usable sample remains to be seen (Hendriks et al, 2022).
Recently, an exciting interdisciplinary concept involving the crossover between forensic analysis techniques and archaeology was proposed. The development of the field of molecular archaeology revolves around the identification of molecules like DNA found on excavated objects and their utility in piecing together the pictures of our past. Many scholars now believe that this field could be advanced by using forensic techniques that are currently used at crime scenes (Dzehverovic et. al, 2023). One such technique is the usage of STRs (short tandem repeats), which are repeating sequences of base pairs at the ends of chromosomes, to identify the sex and genetic makeup of humans that have had contact with a certain excavated object (Schlabitsky et. al, 2006). Amplifying STRs through procedures like PCR (polymerase chain reaction) can also allow scientists to make more detailed observations about the humans who have had contact with an object, including the deduction of their race and ancestral background. Forensic techniques also tend to place an emphasis on collecting mitochondrial DNA (mtDNA). The presence of mtDNA in each mitochondrion means that there is a higher likelihood of finding it intact in comparison to nuclear DNA. The extraction of mtDNA from ancient human remains like bone and teeth has been proposed and tested to be a very efficient and the optimal mode of DNA collection (Schlabitsky).
Another useful technique used to study artifacts is scanning electron microscopy (SEM). SEM produces an image by emitting a narrow beam of electrons through an “electron gun.” The archaeologist then focuses it through “lenses” and scans it back and forth rapidly across the sample (Olsen, 1998). There are three types of imaging within SEM, based on what happens as the electron beam hits the sample: backscattered electrons, secondary electrons, and X-rays.
Secondary electron microscopy can be used to look into organic and decaying samples excavated at a dig site (Postek et. al, 2016).
(c.https://www.jeol.com/words/semterms/20190129.113542.php#gsc.tab=0).
Backscattered electron microscopy allows scientists to observe different chemical composition phases, and piece together the process used to develop inorganic materials in the ancient world, as opposed to the organic materials more commonly studied by secondary electron microscopy.
The last type, electron-density x-rays, are the most widely used (Olsen). The process to generate the X-rays as pulses is completely automated and the results show a variety of peaks, each indicating the relative quantity of each element in a sample. This technique is particularly useful for analyzing a buried or corroded artifact to determine which parts of the artifact are still viable for further scientific investigation.
These techniques represent merely the tip of the iceberg when it comes to the modern science behind archaeology. The advent of revolutionary technology and the emergence of interdisciplinary ideas makes the field of archaeology a promising one in the coming years.
Sources:
Hendriks, L., Portmann, C., Helv. Chim. Acta 2023, 106, e202200134. Brunner M, von Felten J, Hinz M, Hafner A. Central European Early Bronze Age chronology revisited: A Bayesian examination of large-scale radiocarbon dating. PLoS One. 2020 Dec 28;15(12):e0243719. doi: 10.1371/journal.pone.0243719. PMID: 33370331; PMCID: PMC7769557.
Mirela Dzehverovic, Belma Jusic, Amela Pilav, Tamara Lukic, Jasmina Cakar, Kinship analysis of skeletal remains from the Middle Ages,
Forensic Science International: Genetics, Volume 63, 2023, 102829, ISSN 1872-4973, https://doi.org/10.1016/j.fsigen.2023.102829.
Postek MT, Vladár AE, Villarrubia JS, Muto A. Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope. Microsc Microanal. 2016 Aug;22(4):768-77. doi: 10.1017/S1431927616011430. Epub 2016 Jul 25. PMID: 27452278; PMCID: PMC5113026.
Sandra L. Olsen, Applications of Scanning Electron Microscopy in Archaeology, Editor(s): Peter W. Hawkes, Advances in Electronics and Electron Physics, Academic Press, Volume 71, 1988, Pages 357-380,
https://www.jeol.com/words/semterms/20190129.113542.php#gsc.tab=0
Schablitsky, J., Dixon, K. J., & Leney, M. D. (2006). Forensic Technology and the Historical Archaeologist. Historical Archaeology, 40(3), 1–7. http://www.jstor.org/stable/25617368
