Age, taphonomic history and mode of deposition of human skulls in the river Thames

A collection of human skulls from the river Thames has been examined in order to establish age, taphonomic history and mode of deposition. In particular the idea of ritual deposition of skulls in rivers and other wet places during the Bronze Age and Iron Age in Britain is considered. Assessment of cranial surface condition and relative intactness revealed a range of damage from minimal to severe. 50% of skulls were in relatively good condition, implying rapid submersion of fleshed heads or defleshed skulls in river silts in slow moving water or adjacent marsh/bog. The remainder showed varying loss of fragile and robust components, compatible with collisions during fluvial transport. The occurrence of occasional skulls with mandibles and isolated mandibles indicates that at least 10% entered the water as complete bodies or heads and were most likely the result of accident, murder, suicide or riverside burial. The paucity of mandibles and absence of postcranial bones is an argument for selective placement of isolated skulls; however, modern forensic studies have shown that heads and skulls are often rapidly separated from the remainder of the torso in fluvial conditions. Thus there is no definitive taphonomic evidence to distinguish selective deposition from cases in which whole skeletons or corpses entered the water. Estimation of cranial indices for skulls from the Thames, and its tributary the Walbrook, showed that both groups exhibited a mix of phenotypes but the makeup of each group differed. The Thames skulls tended to show head shapes associated with Bronze Age and later medieval populations, while the Walbrook skulls inclined more to shapes that have been associated with Iron Age and Romano-British populations. Radiocarbon dating of six Thames skulls revealed specimens dating across a 3,500 year span, from Neolithic to medieval, and brought the total number of dated Thames skulls to thirteen. More than half of these are from the Bronze Age and most were recovered within a very short river distance, between Kew and Mortlake. This could reflect settlement patterns, but other factors, including sampling by dredging, local topography, dynamics of river flow and burial patterns, are likely to have affected the distribution. It is of interest that recent excavations have revealed that erosion of riverside burials dating from the Bronze Age to the Romano-British period may be a significant source of river skulls.