An actualistic study into the effects of lime and gypsum on human remains for a better understanding of neolithic plaster burials in Southwest Asia

Pre-Pottery Neolithic plaster burials in Southwest Asia have received little attention to date despite their relative frequency. This study is the first experimental attempt to gauge the effect of lime and gypsum plaster on human decomposition. Three human donors were buried at the Australian Facility for Taphonomic Experimental Research (AFTER). The donors, bound with rope and partly covered with ochre, were placed on the left side in a flexed position, similar to the position of Neolithic skeletons in funerary contexts in Southwest Asia. One donor was covered with hydrated lime (Ca(OH)2), another with gypsum (CaSO4.2H2O), and one was unplastered, serving as a control. The results show that after an average of 58 months of burial, all the donors were skeletonising, with the unplastered donor in a slightly more advanced stage than the lime and gypsum donors. Disarticulation and bone movement were limited. Knee flexion angles became wider in all donors. Both plaster casts showed hair, body, rope and ochre impressions, similar to Neolithic observations. While it remains difficult to define a single type of plaster burial across prehistoric Southwest Asia and understand the intent behind this funerary practice, this experimental study offers an important opportunity to gain a more dynamic understanding of the early stages of decomposition in the presence of plaster, insights that are not otherwise obtainable from archaeological contexts. The findings offer valuable information on plaster burials and further emphasize their significance in prehistoric Southwest Asia, while also providing relevant information applicable to forensic casework.