www.nature.com/scientificreports OPEN 2000 Year‑old Bogong moth (Agrotis infusa) Aboriginal food remains, Australia Birgitta Stephenson1, Bruno David2,3*, Joanna Fresløv4, Lee J. Arnold5, GunaiKurnai Land and Waters Aboriginal Corporation4, Jean‑Jacques Delannoy2,6, Fiona Petchey2,7, Chris Urwin2,3, Vanessa N. L. Wong8, Richard Fullagar9, Helen Green2,10, Jerome Mialanes2,3, Matthew McDowell2,11, Rachel Wood2,12 & John Hellstrom10 Insects form an important source of food for many people around the world, but little is known of the deep‑time history of insect harvesting from the archaeological record. In Australia, early settler writings from the 1830s to mid‑1800s reported congregations of Aboriginal groups from multiple clans and language groups taking advantage of the annual migration of Bogong moths (Agrotis infusa) in and near the Australian Alps, the continent’s highest mountain range. The moths were targeted as a food item for their large numbers and high fat contents. Within 30 years of initial colonial contact, however, the Bogong moth festivals had ceased until their recent revival. No reliable archaeological evidence of Bogong moth exploitation or processing has ever been discovered, signalling a major gap in the archaeological history of Aboriginal groups. Here we report on microscopic remains of ground and cooked Bogong moths on a recently excavated grindstone from Cloggs Cave, in the southern foothills of the Australian Alps. These fndings represent the frst conclusive archaeological evidence of insect foods in Australia, and, as far as we know, of their remains on stone artefacts in the world. They provide insights into the antiquity of important Aboriginal dietary practices that have until now remained archaeologically invisible. Ethnographic accounts from around the world have reported the widespread use of insects as food by people 1–3. In some cases, such as among the Shoshone and other Great Basin tribes of the U.S., swarms of grasshoppers and crickets were driven into pits and blankets 4, while among the Paiute the larvae of Pandora moths (Coloradia pandora lindseyi) were smoked out of trees to fall into prepared trenches, where they would be cooked5. Across the world, insects could be mass-harvested, ofen seasonally, ofering high nutritional value especially in fat, protein and vitamins6. Te harvesting of insects in the past has ranged from opportunities to feed large communal gatherings during times of plenty, to more individualistic economic pursuits such as in the search for delicacies or the exploitation of low-ranked resources when other foods were scarce or depleted 7–9. Irrespective of the catch, insects ofen represented an important component of the diet, and of the reliability and thus dependability of locales as resource zones, with implications for social scheduling and cultural practice. However, a paucity of archaeological studies of insect food remains has resulted in a downplay or omission of the use of insects from archaeological narratives and deep-time community histories10. In Australia, a wide range of insects is known to have been eaten by Aboriginal groups, in particular the larvae (‘witchetty grubs’) of cossid moths (especially Endoxyla leucomochla) in arid and semi-arid areas11–13. Of 1In the Groove Analysis Pty Ltd., Brisbane, QLD, Australia. 2Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, Canberra, ACT , Australia. 3Monash Indigenous Studies Centre, 20 Chancellors Walk, Monash University, Clayton, VIC 3800, Australia. 4GunaiKurnai Land and Waters Aboriginal Corporation, Kalimna West, VIC, Australia. 5School of Physical Sciences, Environment Institute, and Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide, SA, Australia. 6Laboratoire EDYTEM, Université Savoie Mont Blanc, 73376 Le Bourget du Lac Cedex, France. 7Radiocarbon Dating Laboratory, University of Waikato, Hamilton, New Zealand. 8School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia. 9Centre for Archaeological Science, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia. 10School of Earth Sciences, University of Melbourne, Parkville, VIC, Australia. 11School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia. 12Radiocarbon Facility, Research School of Earth Sciences, Australian National University, Acton, ACT , Australia. *email: bruno.david@ monash.edu Scientifc Reports | (2020) 10:22151 | https://doi.org/10.1038/s41598-020-79307-w 1 Vol.:(0123456789) www.nature.com/scientificreports/ Figure 1. (A) Bogong moth, Agrotis infusa (photo: Ajay Narendra). (B) Tousands of moths per square metre aestivating on a rock surface (photo: Eric Warrant). particular interest to archaeologists and behavioural ecologists has been the seasonal consumption of Bogong moths by mass gatherings of Aboriginal groups in the southern portions of the Eastern Uplands14 (Fig. 1). How- ever, no conclusive archaeological evidence has ever been reported for the processing or use of Bogong moths. The Cloggs Cave grindstone. Cloggs Cave is located 72 m above sea level in the southern foothills of the Australian Alps, in the lands of the Krauatungalung clan of the GunaiKurnai Aboriginal peoples of southeastern Australia (Fig. 2). Te cave is a small, 12 m long × 5 m wide × 6.8 m high limestone karst formation that is today entered through a walk-through opening on the side of a clif (Fig. 3). Indirect sunlight dimly illuminates the cave for much of the day (Supplementary Fig. S1). Archaeological excavations were frst undertaken in 1971–197214, followed by a new program of excavations in 2019–2020, initiated by the GunaiKurnai Land and Waters Aboriginal Corporation and directed by Bruno David. Te new excavations were aimed at better determining the site’s stratigraphy and the antiquity of Abo- riginal occupation (Supplementary Fig. S2). An intensive dating programme showed that the oldest excavated evidence for human activity dates to between 19,330–19,730 cal BP (median age of 19,530 cal BP; cal BP = before AD1950) and 20,590–23,530 cal BP (median age of 21,690 cal BP) (all calibrated radiocarbon ages in the text are presented at 95.4% probability range. See “Methods”; Supplementary Fig. S3)15–17. During the 2019 excavations, a small, fat grindstone was found. Te fnely stratifed hearth layers of strati- graphic unit (SU) 2 in which it was found were radiocarbon-dated to 1567–1696 cal BP at their top (uncalibrated: 1724 ± 16 BP; median age of 1632 cal BP) and 2002–2117 cal BP at their base (uncalibrated: 2091 ± 16 BP; median age of 2062 cal BP). Te grindstone therefore dates to between 1600 and 2100 years ago (see “Methods”; Sup- plementary Figs. S3 and S4)17. No other grindstone has been found at Cloggs Cave. Te grindstone is a tabular fragment of sandstone with two fat and parallel ground surfaces (Surfaces A and B), in the form of a fat dish (Fig. 4). It measures 10.5 cm long × 8.3 cm wide × 2.2 cm thick and weighs 304 g. Te outer, intact margin is elliptical in plan view; the other three margins indicate old breaks that have been subsequently worn from use. Terefore, prior to its deposition at Cloggs Cave, the grindstone had been used in its current form. To understand how the grindstone was used, we undertook use-wear and residue analyses (see “Methods”). Te central area of both its surfaces contain fne unidirectional striations (Supplementary Figs. S5A and S5B), a lowered but not levelled topography, and areas of missing or ripped quartz grains (Supplementary Figs. S5C and S5D). Its use to shape ground stone axes is an unlikely function because the Cloggs Cave grindstone surfaces are relatively fat with only very slight concavities, and the lowered surface topography (Fig. 4) lacks broad grooves typical of axe grinding. When viewed at lower (up to 5 ×) magnifcation under a stereozoom microscope with a point source of light, each surface appears relatively rough compared with grindstones used for processing seeds, which, in Australia, tend to be highly smoothed and polished18,19. Tere are numerous ‘pits’ where sand grains have been plucked from the surface during use (Supplementary Fig. S5D). Te presence of a lowered surface topography (Supplementary Fig. S5C) with a lack of smooth, developed polish suggests that the stone was not used to process siliceous plants. Te repeated mechanical action of grinding has been shown to force residues into the voids and interstitial spaces of ground surfaces, where they become trapped 20–22. Residue analyses conducted on grindstones world- wide have relied on microscopic observations of individual residue morphologies. However, visually diagnostic features can be altered by the mechanical forces of grinding, heat, and contact with water and various envi- ronmental factors, which can cause residues to swell or become amorphous 21–24. Te distinctiveness of residue Scientifc Reports | (2020) 10:22151 | https://doi.org/10.1038/s41598-020-79307-w 2 Vol:.(1234567890) www.nature.com/scientificreports/ Figure 2. Location of Cloggs Cave and the area of the GunaiKurnai Land and Waters Aboriginal Corporation, at the southern foothills of the Australian Alps. Esri ArcMap 10.5 (https ://deskt op.arcgi s.com/en/arcma p/) and Adobe Illustrator CC 2017 (21.0) (https ://helpx .adobe .com/au/illus trato r/relea se-note/illus trato r-cc-2017-21-0- relea se-notes .html) were used by CartoGIS Services, College of Asia and the Pacifc at the Australian National