Eight meters below the floor of a limestone cave in South Sulawesi, archaeologists have uncovered stone tools and animal butchery evidence left behind by a human-like species that lived on the island roughly 132,000 to 208,000 years ago. The find comes from Leang Bulu Bettue, a cave and rock-shelter complex in the Maros-Pangkep karst region of Indonesia, and it represents the only known site on Sulawesi with an unbroken archaeological record stretching from the Middle Pleistocene through to the late Holocene.
The study, led by Basran Burhan and Adam Brumm of Griffith University and published in PLOS ONE in December 2025, draws on seven excavation seasons conducted since 2013. What the team found in those deepest layers raises a pointed question about human prehistory in Southeast Asia: who exactly was living on this island long before Homo sapiens arrived?
A Tool Tradition That Predates Modern Humans on the Island
The older of the two occupation phases identified at Leang Bulu Bettue, which the researchers call Phase I, is defined by a cobble-based core and flake technology. Among the artifacts recovered is a stone “pick,” a heavy-duty tool whose presence the authors say reflects both the technical capability and the environmental adaptation of these early inhabitants. Faunal remains in the same layers show evidence of animal butchery, with assemblages dominated by dwarf bovids known as anoas, alongside the bones of now-extinct proboscideans.
No hominin fossils were found at the site, so the identity of the species responsible for this tool tradition remains unresolved. According to the study published in PLOS ONE, prior research has established that Sulawesi hosted archaic hominins from at least 1.04 million years ago.
The authors say the most plausible candidate based on the regional fossil record is Homo erectus or a dwarfed, insular variant of that species. They also raise the possibility of Denisovans, noting that genomic research has linked the ancestors of present-day Aboriginal and Melanesian peoples to Denisovan interbreeding before the peopling of Sahul, and that Sulawesi is considered one of the most likely locations within Wallacea where that genetic exchange could have occurred.
A Sharp Cultural Break Around 40,000 Years Ago
The deeper layers are not the only story at Leang Bulu Bettue. Above them, the record shifts abruptly.
By roughly 40,000 years ago, the Phase I occupation had been replaced by an entirely different cultural signature. The new phase brought a distinct lithic technology, the use of ochre, portable art including stone pieces incised with abstract markings, personal ornaments made from animal bones and teeth, and what the researchers describe as the earliest known evidence for artistic expression and symbolic behavior on Sulawesi.
Brumm described the transition as likely reflecting a major demographic and cultural shift on the island. As reported by Indian Defence Review, the authors write that the behavioral break between the two phases is consistent with the replacement of the archaic hominin population by arriving Homo sapiens, though they are careful to note this remains an inference rather than a confirmed conclusion.
The oldest direct evidence for modern humans on Sulawesi is a cave painting at nearby Leang Karampuang, dated using uranium-series dating methods to at least 51,200 years ago.
Sulawesi as a Crossroads for Human Dispersal
The significance of Leang Bulu Bettue extends beyond the two occupation phases themselves. Sulawesi sits along one of the two most probable human dispersal routes used by early modern humans as they moved east from the Sunda landmass toward Sahul, the Pleistocene-era continental landmass comprising Australia and New Guinea. Its position makes the island a potential corridor through which multiple hominin species may have passed or settled at different times.
Prior to the Leang Bulu Bettue excavations, the evidence available from Sulawesi left a significant gap between the archaic hominin presence documented at older sites and the appearance of Homo sapiens.
The near-continuous stratigraphic sequence at this site, reaching roughly eight meters below the modern surface and spanning from the Middle Pleistocene to the late Holocene, is what makes it unusual. No other site on the island currently offers a comparable record.
Deeper Layers May Still Hold Answers
The excavation is not finished. The researchers note that several more meters of deposits below the current excavation depth remain unexplored, and those layers could contain older artifacts and additional evidence of earlier hominin activity in Indonesia.
Burhan said that further work at the site could produce discoveries that change the understanding of the early human story on Sulawesi and potentially across the wider region.
As of the study’s publication, Leang Bulu Bettue remains the only site on Sulawesi with a dated archaeological record covering the Middle and Late Pleistocene Epoch continuously, making it the primary reference point for understanding when and how different hominin species occupied the island before and after the arrival of modern humans.
