Pandanus nutshell generates a palaeoprecipitation record for human occupation at Madjedbebe, northern Australia

Abstract

Little is known about the Pleistocene climatic context of northern Australia at the time of early human settlement. Here we generate a palaeoprecipitation proxy using stable carbon isotope analysis of modern and archaeological pandanus nutshell from Madjedbebe, Australia’s oldest known archaeological site. We document fluctuations in precipitation over the last 65,000 years and identify periods of lower precipitation during the penultimate and last glacial stages, Marine Isotope Stages 4 and 2. However, the lowest effective annual precipitation is recorded at the present time. Periods of lower precipitation, including the earliest phase of occupation, correspond with peaks in exotic stone raw materials and artefact discard at the site. This pattern is interpreted as suggesting increased group mobility and intensified use of the region during drier periods.

65,000-years of continuous grinding stone use at Madjedbebe, Northern Australia

“…Generally, grinding stones were most common in Pleistocene Phases 2 and 4 and Holocene Phases 6 and 7. Greater abundance mostly corresponds with drier phases (Table 1 ), although Florin et al 73 conclude from a study of charred pandanus ( P. spiralis ) δ13C records from the site that rainfall in the vicinity of Madjedbebe may have remained relatively high, even during the driest phases, consistent with arguments that the region may have seen more intensive occupation during the drier periods of MIS 4 and 2 74 . Grinding stones in Phases 2, 4, 6 and 7 are associated with increases in plant food diet breadth as reflected by the archaeobotanical remains from the site, some of which involved grinding and pounding, including seeds, hard nuts and some fruits 50 .…”

“…This corresponds to the sediments below Phase to the lowest excavated deposits 0 0 2 68.7–50.4 A period of relative aridity at the end of MIS 4 181 29 3 54.0–26.0 A variable period of increased precipitation during MIS 3/2 112 16 4 28.9–12.2 The Last Glacial Maximum peaking at c.22–18 ka 111 33 5 10.5–7.1 A period of increased precipitation (Early Holocene Optimum) and rising sea levels culminating in the marine transgression c.8 ka at the end of MIS 2 and beginning of MIS 1 53 15 6 9.1–5.8# A period of increased precipitation and the formation of estuarine environments along the South Alligator River 42 4 7 4.7–0.0# A period of intensified El Niño Southern Oscillation (ENSO) conditions, more variable and decreased precipitation. The transition from estuarine to freshwater vegetation communities on the Alligators Rivers’ lowlands takes place at this time due to increasing sedimentation from approximately 3.3 ka, culminating in the formation of the Magela Creek floodplain freshwater wetlands at 1333–1062 cal BP 38 , 73 64 5 Uncertain 2 563 104 #Age range for Phases 6 and 7 are based on the oldest and youngest OSL and/or 14 C ages. …”

Archaeological identification of fragmented nuts and fruits from key Asia‐Pacific economic tree species using anatomical criteria: Comparative analysis of Canarium, Pandanus and Terminalia

“…Further, even at high fragmentation, monodrupe and polydrupe species of Pandanus can be distinguished based on anatomical criteria. Further speciation is possible in some cases, either via cell wall thickness of monodrupe varieties (Donoghue, 1988;Fairbairn in Summerhayes et al, 2010) or through the identification of further anatomical criteria (e.g., the presence of distinctive mesocarp anatomy; Florin et al, 2020Florin et al, , 2021.…”

“…The assemblage at Madjedbebe was dominated by fragments of polydrupe Pandanus endocarp, identified as P. spiralis (Florin et al, 2020(Florin et al, , 2021. Even though most fragments were small and did not permit for identification on morphological grounds (i.e., through the presence of multiple seed locule walls), the non-uniform nature of the vasculature patterning allowed for their identification as polydrupe Pandanus (see Figure 9b, 9d).…”

Reconstructing archaeological palaeolandscapes using geophysical and geomatic survey techniques: An example from Red Lily Lagoon, Arnhem Land, Australia

“…Florin et al [ 69 ] has investigated palaeoclimate for this region using the novel analysis of Pandanus nutshell ( Pandanus spiralis ) remains excavated from Madjedbebe. Variations within the δ 13 C within this dated assemblage were used as a proxy for mean annual precipitation.…”