X-rays and computers study palm-leaf scriptures.

The DESY research centre reports on a project using two advanced technologies — machine learning and synchrotron X-rays — to study the physical structure of ancient South and Southeast Asian scriptures, legal documents, literary works, and scientific studies written centuries ago on palm leaves:

The study examined 160 material entries: 85 manuscripts, and 75 modern reference materials. The materials came from different collections and regions across South and Southeast Asia. The team investigated whether their material properties could help distinguish the palm genera used, identify different stages of leaf processing and reveal possible links to geographical provenance.

One key advantage of the method is that the analyses are non-destructive. No samples need to be removed from fragile historical objects. Instead, different X-ray techniques provide information about the leaves’ internal structure and chemical composition.

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Laura Gallardo, first author of the study and scientist at Hamburg University of Technology (TU Hamburg), emphasises the importance of the non-destructive approach: “For rare and fragile cultural artefacts, the ability to obtain rich structural and chemical information without taking a sample is essential. By combining several synchrotron techniques, we can read different layers of a manuscript’s material history in a single experiment and compare large numbers of objects in a systematic way.”

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The researchers combined three techniques, each of which captures different properties of the palm leaves. Small-angle X-ray scattering (SAXS) provides information about the structure and orientation of fibre networks. Wide-angle X-ray scattering (WAXS) provides information on the relative contributions of crystalline cellulose and amorphous substances. X-ray fluorescence (XRF) maps the distribution of chemical elements within the material.

The team used machine learning to analyse the measurement data together. Rather than relying on a single measurement, the approach draws on combinations of structural and chemical characteristics to distinguish between materials.

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The samples examined from Sri Lanka and southern India showed substantial material similarities, which may be associated with related processing traditions. The Thai samples displayed a comparatively distinct material profile in the dataset, which may be related to the unique processing traditions in some areas of Thailand. Systematic material differences identified between the groups suggest material fingerprints related to regional processing practices, but reliable geographical attribution is not yet possible, as some provenance groups were represented by relatively few samples and the influence of ageing and preservation conditions on the material properties could only be partially assessed.

Patrick Huber, Director of the Institute of Materials and X-ray Physics at TU Hamburg and head of the “High-Resolution X-Ray Analytics of Materials” research group at DESY, explains this limitation: “The material data alone cannot yet establish geographical provenance with certainty. The properties of the leaves are shaped by several interacting factors, and the available sample groups are not equally large. The findings therefore need to be interpreted alongside historical and codicological evidence.”