Identification of preserved fatty acids in archaeological floor sediments from prehistoric sites at Ban Non Wat and Nong Hua Raet in northeast Thailand using gas chromatography

This paper presents the first record of fatty acids recovered from archaeological sediment samples in Southeast Asia. Fatty acid analysis in archaeology provides a good source of evidence for the identification and interpretation of prehistoric dietary patterns by identifying organic remains of animal and plant foods. Prehistoric hard floor sediment samples excavated from prehistoric sites of Ban Non Wat and Nong Hua Raet located in the upper catchment of the Mun River valley in Thailand, were analysed for this study. The samples are from compressed sediment features identified during excavation as ‘floors’ and interpreted as some form of living or working surfaces, dated to the Iron Age and Neolithic periods, around 2000 BC–AD 500. Triglycerides were extracted in hexane, derivatized to fatty acid methyl esters and analysed using Gas Chromatography-Flame Ionization Detector and Gas Chromatography-Mass Spectrometry. Twenty fatty acids, including saturated and unsaturated counterparts, were identified in the hard floor sediments. Comparison with control samples indicate that the floor samples have distinctive fatty acid assemblages, interpreted to relate to the anthropogenic activity associated with the formation of the floors. Results suggest that many of the fatty acids are mainly of degraded animal origin, possibly from ruminants, including cow and deer.