Archaeochemistry

Archaeochemists play a crucial role in applying chemical techniques and methods to archaeology.

In broad terms, molecular archaeology and archaeochemistry focus on the study of ancient molecules to piece together the processes that occurred in the past. Significant contributions of archaeochemistry to archaeology include source provenance studies, residue analysis, activity area analysis, and reconstruction of production technologies (e.g. glass working, metallurgy or ceramic manufacture). It is safe to say that an archaeochemist can deal with multiple aspects of archaeological processes, objects, technical installations, equipment and buildings.

The work of archaeochemists involved in the Liang Bua project is focussed on identifying organic residues on stone artefacts (residue analysis), which is central to shedding light on the types of resources used by hobbits (and how these compare with those used by modern humans). They also analyse sediments to aid geoarchaeological understanding of the chemical processes that have occurred in the cave and to determine the presence of hominin activity (e.g. fire use, resource processing, presence of faecal matter). For this purpose X-ray fluorescence spectroscopy can be used to analyse sediments in situ. The process of X-ray fluorescence involves bombarding a small volume of samples that are emitted to establish the chemical elements present in the sample.

Collectively, the team of scientists working on the Liang Bua project use gas and liquid chromatography, mass spectrometry and vibrational spectroscopy techniques. The archaeochemists have adopted a multidisciplinary approach to analyse artefacts from the site and maximise the amount of information obtained from each artefact using complementary techniques. They follow a model in which they start with non-destructive analyses and move towards more destructive techniques (where the molecules are removed from the artefact) as follows:

Least to Most Destructive

• Use-wear analysis by optical microscopy (non-destructive)
• Fourier-transform Infrared (FTIR) spectroscopy and Raman spectroscopy (also non-destructive)
• Chromatography and mass spectrometry (most destructive)