A lack of freshwater reservoir effects in human radiocarbon dates in the Eneolithic to Iron Age in the Minusinsk Basin

Abstract

A number of recent studies have highlighted the importance of freshwater reservoir effects (FRE) when dating human remains across large parts of Eurasia, including the Eurasian steppes. Here, we address this question in the context of the Early Bronze Age (Okunevo), Late Bronze Age (Karasuk) and Late Iron Age (Tashtyk culture) of the Minusinsk Basin, Southern Siberia. The issue is important given the large number of radiocarbon dates that have been published on human remains here, which have been used both to refine the cultural historical sequence (Svyatko et al. 2009), as well as to suggest a date of ca. 1400 bc for the appearance of millet agriculture (Svyatko et al. 2013). In these studies, it was argued that there was little or no freshwater reservoir effect to take into account, despite the likely consumption of freshwater fish. Subsequent work across the steppe raised a legitimate question concerning this assumption. Here, we present the first set of paired dates on late prehistoric humans and terrestrial fauna from the Minusinsk Basin, as well as data from modern fish for the region. The results, with one exception, show no clear evidence for a reservoir effect, with the human-fauna difference averaging −31 ± 95 14C years. Yet, dating of modern fish from the Yenisei River and its tributary Karasuk River does show a variable but significant FRE. Either this effect has changed radically over time, or the contribution of fish to human diets in the Minusinsk Basin was less than previously thought.