Ice Age Human Jawbone Found on Indonesian Island Known for Ancient Cave Art

Ice Age Human Jawbone Found on Indonesian Island Known for Ancient Cave Art

An international team of paleontologists discovered a human jawbone in a cave in southwestern Sulawesi, one of the major islands of Indonesia. The remains are the first indication of a human presence on the island during the Pleistocene epoch, a period of great climatic change and rapid human dispersal.

The jawbone — complete with teeth — was dated to between 25,000 and 16,000 years ago, though the team wasn’t able to determine the individual’s sex or age. Their results were published today in PLoS One.

This particular individual most likely descended from a population of modern humans that arrived in Sulawesi by watercraft tens of thousands of years ago,” lead author Adam Brumm, an archaeologist at the Australian Research Centre for Human Evolution at Griffith University in Brisbane, told Gizmodo in an email.

Southeast Asia boasts a remarkable archive of hominin remains tucked away in its limestone caves. In recent years, islands in the Philippines and Indonesia have hosted the discoveries of Homo floresiensis and Homo luzonensis, extinct human relatives named for the islands on which they were discovered. In the ancient past, hominins (our own species and others) made their way through the island chains, setting up shop in the region’s caves and painting on their walls. Some in the Philippines may have dined on giant, tree-dwelling rodents.

The jawbone was found in Leang Bulu Bettue, a cave in Sulawesi’s southwestern region of Maros. The team knew from previous work that the dirt layer the bone came out of was between 25,000 and 16,000 years old, based on several dating methods: isotope analysis of stalagmites exposed during those excavations, radiocarbon dating of shells found in the same layer, laser ablation dating of a pig tooth found there, and optical dating of feldspar rock in the layer. The radiocarbon-dated shell was previously used for the maximum of the layer — about 22,300 years ago — but due to some uncertainty about the way that water can warp the results, in this paper the researchers deferred to the isotope dating of the stalagmites, which have a broader range of 24,800 to 16,000 years old.

Last month, a different team including Brumm announced the recovery of genetic material from a 7,000-year-old skeleton on Sulawesi; the remains belonged to a woman who was 18 years old when she died during the Holocene. The recently reported jawbone predates those remains by an epoch; there was more time between this ancient individual and the Holocene woman than between the Holocene woman and us.

The new find pushes back Homo sapiens’ existence on Sulawesi by thousands of years. “Unfortunately, the specimen is so incomplete and fragmentary that it can’t really tell us much at all about the individual it came from — apart from the fact this person had really bad teeth,” Brumm said. They know the person was an adult, due to an erupted third molar, but they can’t get much deeper than that.

“We would very much like to find more remains of the individual this tiny fragment came from,” Brumm added. “They must be buried somewhere at the site, and if we keep digging, perhaps we will be lucky enough to find them one day — or the remains of other early humans buried in the cave.”

Whether our species coexisted or clashed with other hominins on Sulawesi is unknown, but it’s “certainly possible” that the different groups interacted with each other, Brumm said. They inhabited the same island at the same time, after all. Perhaps future finds will tell more of that story.