Archaeobotany of Aboriginal plant foods during the Holocene at Riwi, south central Kimberley, Western Australia

Riwi, a limestone cave located in the south central Kimberley, northwest Western Australia, has one of the most accurately dated archaeological sequences in Australia, with human occupation beginning between 46,400 and 44,600 cal bp. Macrobotanical remains are well preserved at the site, particularly in upper stratigraphic units 1 and 2 dated to the late and mid-Holocene, respectively. Macrobotanical materials (excluding wood charcoal) are uncommon in Pleistocene contexts, and direct dating of some of the macrobotanical remains recovered from Pleistocene hearths suggest that they derive from the directly superposed Holocene layers. Analysis of the macrobotanical remains from the Holocene layers reveals a pattern where Aboriginal groups occupying Riwi intermittently between 7,000 years ago and the present principally exploited monsoon rainforest ecosystems for food plants, especially Vitex cf. glabrata. Fruiting times of dominant monsoon rainforest taxa indicate that the site was occupied seasonally, corresponding with periods of rainfall when people were able to move away from rivers and other permanent water sources. Results demonstrate a strong cultural preference for fruits associated with monsoon rainforest—a vegetation type restricted in distribution—highlighting the importance of moisture retaining limestone outcrops in foragers’ subsistence organisation in the south central Kimberley.