SUPPLEMENTARY INFORMATION (SI) APPENDIX Early human symbolic behavior in the Late Pleistocene of Wallacea Adam Brumm, Michelle C. Langley, Mark W. Moore, Budianto Hakim, Muhammad Ramli, Iwan Sumantri, Basran Burhan, Andi Muhammad Saiful, Linda Siagian, Suryatman, Ratno Sardi, Andi Jusdi, Abdullah, Andi Pampang Mubarak, Hasliana, Hasrianti, Adhi Agus Oktaviana, Shinatria Adhityatama, Gerrit D. van den Bergh, Maxime Aubert, Jian-xin Zhao, Jillian Huntley, Bo Li, Richard G. Roberts, E. Wahyu Saptomo, Yinika Perston, Rainer Grün Archaeological context The cave and rock-shelter complex of Leang Bulu Bettue (LBB) (4°59'31.18"S, 119°40'5.53"E) is situated at the foot of a limestone tower in the Maros-Pangkep karst area, which lies between 4˚7´S and 5˚1´S on Sulawesi’s southwestern peninsula. The topography of this extensive karst landscape (~450 km2) is dominated by plateau-like hill masses formed by rivers cutting through intersecting joints in the limestone, and, in areas of advanced plateau dissection, steep-sided towers surrounded by alluvial plains that extend to the western coastline at an elevation of ~5 to 30 m a.s.l. (1). Some 120 sites with archaeological evidence for prehistoric human occupation, mostly in the form of rock art and/or surficial artifact scatters (e.g., flaked stone implements, ceramics, and shell midden refuse), have been recorded in this region. Prior to the current research, the oldest excavated archaeological findings dated to 35.6–34.5 ka cal B.P., as revealed by excavations at the Maros rock-shelter Leang Burung 2 (2). Some 20 km to the north, where the limestone karst crops out in the adjoining Pangkep district, excavations at a rock art site located 20 m above the alluvial plain, Leang Sakapao 1, yielded in situ stone artifacts and shellfish remains with a (nominal) maximum age of 30–20 ka (3). LBB is located within a precinct of major prehistoric sites: Leang Burung 2 is 1.5 km to the south (2); 1 km to the southwest is Leang Timpuseng, a rock-shelter with a hand stencil and large figurative painting of a female babirusa ‘pig-deer’ with minimum Uranium-series (U-series) ages of 39.9 ka and 35.4 ka, respectively (4); and 300 m to the northwest is Ulu Leang 1 cave (5). The latter cave site has yielded the region’s best-known record of the Toalean (6-8), a regionally unique industry of purportedly Mesolithic character and presumed middle to late Holocene antiquity (5, 9, 10). The Toalean is characterized by backed blades, geometric microliths, and small pressure-flaked projectiles with hollow bases and serrated margins (‘Maros points’). LBB is currently situated 20 km east of the modern coastline. However, a 40-60 km-wide carbonate platform (known as the ‘Spermonde Shelf’) lies off the modern coastline of Sulawesi’s southwestern peninsula adjacent to the alluvial plains fronting the Maros-Pangkep karsts (11-12). Presently, the shelf harbors a network of 67 low-lying coral atoll islands, as well as platform reefs, submerged patch reefs, and sea-grass meadows, and it is bordered on its western side by a discontinuous barrier reef (11). Referred to locally as the Sangkarang islands, the 200 km-long Spermonde archipelago is one of Indonesia’s largest coral archipelagos, and it contains what is probably the largest reef fishery in the region. The maximum shelf depth varies from 20 to 60 m (11-12), and hence it is likely the Spermonde Shelf would have been exposed as dry land when sea level dropped to below -60 m (11). Further, it can be speculated that the major decline in sea levels that commenced ~30 ka would have progressively eliminated the mosaic of shallow coastal flats, estuaries, and coral habitats that would have been established on the shelf during much of MIS3. These highly ranked patches are likely to have been preferentially exploited by AMH colonists whose initial migration through Wallacea is thought, by some, to have relied upon a highly developed marine coastal adaptation with roots that may ultimately extend back into the Middle Stone Age period of southern Africa (13-16). Speleothem δ18O records obtained from U/Th analysis of 77 stalagmites in the Maros-Pangkep 1 karsts lack precise coverage for the time interval covered by the LBB sequence (17). However, high-resolution palaeoclimate records derived from lake sediment cores in central Sulawesi indicate a very wet climate and closed-canopy rainforest during much of MIS3 (~58 to 30 ka) (17-18). This phase is followed by the abrupt onset of a period of severe drying in the transition to the LGM, with the arid phase documented from ~33–16 ka at Lake Towuti (18), and from ~29–14 ka at nearby 13 Lake Matano (19). Biomarker records (δ CWAX) from these two lakes suggest grassland and open- canopy forest expanded during a more arid and seasonal MIS2 (19), with substantial expansion of C4 grasslands between 30 and 18 ka (18). Evidence for a human presence at LBB during most of MIS3 is scant. The low-density cultural assemblages show that people were making short-lived visits to this locality, while rock art is evident at nearby sites from at least 40 ka (4). Resource patches in the karst border plains of Maros-Pangkep may have became increasingly attractive to maritime-orientated populations as the climate became cooler and drier in the millennia preceding the LGM. This situation was owing to the decline in marine productivity along the coast – especially reef habitats on the now-submerged Spermonde Shelf – and the transition from closed- canopy rainforest, where return rates on forager investment are generally seen as being low (15), to open vegetation. LBB comprises a valley floor entrance rock-shelter with a roof height of 15.6 m, and an adjoining, slightly more elevated cave chamber that is 27.3 m long, 12.6 m wide, and up to 9.2 m high. Rock art is visible on the walls and ceiling, including hand stencils (n = 35) overlaid by Austronesian- style drawings (4). During annual excavation seasons at LBB conducted between 2013 and 2015, we opened up a large trench that extended southwards from the cave entrance to the central floor area of the shelter. Our trench has revealed an archaeological sequence of human occupation that is divisible internally and on stratigraphic and chronological grounds into two distinct phases: Phase II: Historical (<1790 A.D.) and ‘Neolithic’ (1.7–1.6 ka cal B.P.); and Phase I: MIS 3/2 (~50–22 ka). The excavated archaeological findings reported in the present study were recovered from Layers 4a- e in Phase I. These are the uppermost Pleistocene deposits preserved at the site. A 108 cm-thick sequence of flowstones separates these sediments from overlying Holocene strata. The capping flowstones sealed-off the Pleistocene layers and protected them from erosion and anthropogenic disturbances. The Layers 4a-e sequence comprises thin silty clays (Layers 4a-b) that slope downwards from the rear of the cave and level out and thicken in the main shelter, where they inter- finger with ashy lenses (Layers 4c-e). This combined sequence is 1.5 m thick. Below this is a 50 cm-thick sandy clay (Layer 4f) that is only preserved near the eastern wall of the cave and which is underlain by a 50 cm-thick sandy clay (Layer 5). Site chronology Dating results for the site are reported in ref. 20 and summarized in SI Table 1. Charcoal preservation in the Pleistocene deposits was extremely poor. Consequently, we conducted solution U-series dating of two in situ, still-emplaced vertical stalagmites that sandwiched Layer 4a, enabling us to bracket the time-range of this key depositional unit. The uppermost stalagmite (Stalagmite 485), which formed directly atop Layer 4a, has a basal U-series age of 13.7 ± 1.8 ka. This result provides a minimum age for Layer 4a and underlying deposits. The lowermost stalagmite (#605) grew on the upper surface of Layer 4b. This speleothem has a basal U-series age of 25.9 ± 0.7 ka, thus providing a maximum age for overlying Layer 4a and a minimum age for Layer 4b and the strata below it. The high-precision U-series stalagmite chronology allows us to bracket the time-depth of Layer 4a to between approximately 26 and 14 ka. In order to more tightly constrain the age of Layer 4a, we conducted AMS 14C-dating of freshwater gastropod (Tylomelania perfecta) shells and laser ablation U-series dating of a pig tooth. We also carried out AMS 14C-dating on two T. perfecta shells collected from laterally continuous exposures of Layer 4a revealed by excavations inside the adjoining rock-shelter. These three independent dating methods allow us to infer a time-depth of 2 approximately 26–22 ka for Layer 4a. Layers 4b-e span ~30–26 ka, as inferred from the overlying stalagmite dates, laser ablation U-series analysis of faunal remains, and radiocarbon dating. A bovid tooth from Layer 4f yielded a minimum U-series age of 39.8 ± 0.2 ka, which, in combination with the above chronological data, suggests this unit spans ~40–30 ka. U-series analysis of a bovid molar from basal Layer 5 provided an in- sequence minimum age of 51.8 ± 0.6 ka, providing Layer 5 with a provisional time-range of ~50– 40 ka. We also undertook optical dating on two samples LBB-I and LBB-II from Layer 4a and Layer 5, respectively, based on infrared stimulated luminescence (IRSL) measurements on volcanic !!.! feldspars (see ref.