New insights into human behavior at Liang Bua (Flores, Indonesia) based on the temporal distribution of pottery and mollusks during the past 5000 years

In addition to preserving a rich archaeological record spanning from ∼190 thousand years ago (ka) until the terminal Pleistocene, Liang Bua (Flores, Indonesia) also preserves a rich and relatively complete Holocene stratigraphic sequence with dense accumulations of faunal remains, stone artifacts, and pottery. In this study, abundances of pottery sherds and mollusk taxa were examined across nine stratigraphic units to explore temporal variation during the past ∼5000 years. This temporal period is important because it is during this time that archaeological evidence of agriculture and sedentism initially appears on Flores. The first aim of this study was to more precisely determine when pottery was first introduced to the site as previous research has suggested that this occurred either ∼4 ka or ∼3 ka. The second aim of this study was to document the mollusk assemblage at Liang Bua in terms of its temporal range and taxonomic composition. Particular emphasis was placed on determining whether humans were responsible for accumulating all or part of this mollusk assemblage, which included 3515 three-dimensionally-plotted specimens and 4270 specimens recovered from sieved sediments.

Our results show that pottery was most likely first introduced to the site ∼3.3 ka and used regularly after ∼3 ka, suggesting increased sedentism or farming in the areas surrounding the cave. The main shell midden at Liang Bua was deposited between ∼4.4 and 3.3 ka and includes mostly freshwater species. Interestingly, 63.1 % of Tarebia granifera and 66.7 % of Melanoides tuberculata recovered in Sectors XXXII-XXIX showed signs that they were deliberately broken open at their apices. Deliberately opening the apex of a shell is almost certainly a strategy to obtain the meat for human consumption. Furthermore, the presence of 12 culturally modified marine shells at Liang Bua suggests that, after ∼4.4–4.3 ka, past peoples living around Liang Bua had strong social and/or symbolic connections to coastal areas either through their own foraging ranges or through trade networks with other peoples living nearer to the ocean.