Decoding the secrets of a forgotten human history during the Pleistocene

An international team of researchers has discovered the first fossilised bone from a Pleistocene-era human in Wallacea, the cluster of Indonesian islands, including Lombok, Sulaewsi, Timor and Sumba, that were the likely seafaring gateway for the first humans to populate Australia.

The new find, published today in the journal PLOS one, offers a tantalising glimpse of a forgotten people, but one of the archaeologists behind the research says that the information we currently don’t know about these people vastly outweighs the fascinating crumbs they’ve left behind.

“We’ve found the first human skeletal remains from the Ice Age on the island of Sulawesi,” says study co-author Adam Brumm, an archaeologist from Griffith University who has dedicated his working life to the secrets of ancient Wallacea. “It’s important because it’s the first time we have the biological remains of the people that we think were some of the earliest humans to live on Sulawesi, and their story’s important because these people made some of the oldest rock art in the world.

“But the problem is it’s just a very small fragmentary piece of the upper jawbone, and we really can’t tell too much.”

---

Read more: First ancient human DNA from the gateway between Asia and Australia

---

Wallacea, the authors write, has a “long and enigmatic history”. It’s from Wallacea that the earliest migration to the continent of Sahul – modern day Australia – must have occurred, with evidence showing human occupation of Australia by at least 70,000 to 60,000 years ago – so our continent’s story is intimately connected to that of Wallacea.

It’s also in Wallacea that many other fascinating human stories played out. From the evolution of the tiny Homo floresiensis in Flores and Homo luzonensis in the Phillipines to the Neolithic incursions of Austronesian farmers, the region’s limited skeletal record belies a wealth of actual history.

The jawbone in question belonged to a person who lived at some time between 25,000 and 16,000 years ago. They were elderly, of an undetermined sex, and had severe dental wear and tooth loss that probably caused them some pain.

The context and dating of the find has enabled the archaeologists to piece together hints about the culture of the person in question. The bone was excavated by archaeologists from Indonesia and Australia in a limestone cave site called Leang Bulu Bettue, part of a sprawling network of limestone cave sites holding hundreds of shelters in which people lived, died and made art. The chronological layer from which the bone was excavated is a fertile archaeological horizon that has, in other sites, yielded evidence for portable art, personal ornaments and pigment use.

But beyond these facts, Brumm says precious few conclusions can be drawn about the life of this individual.

In fact, Brumm and his colleagues have made a career out of this kind of archaeological sleuthing, hunting for scarce clues in a deeply under-studied region. Brumm says looking for sites that might host human remains is a deeply involved process.

“You look for cave sites that are quite large, close to freshwater sources, a fairly flat ground surface,” he says. “But ultimately, what you’re looking for as an archaeologist is a sediment trap. You want to find a site that ancient people lived in, and [in which] archaeological layers have built up over the thousands of years they lived at the site, and you want to know that they haven’t been rinsed out, washed away by erosion in subsequent millennia.”

Evidence of a sediment trap, Brumm says, would include large boulders that have fallen down at the front of the site and trapped sediment behind them. But there are no certainties in archaeology.

“Sometimes you can have a site that looks great on surface appearances, then you spend all this time excavating and it’s not so great. It’s a bit of a crapshoot as to what you’re going to find.”

This isn’t the first time Brumm and colleagues have found something unprecedented on Sulawesi. In August this year, in a paper published in the journal Nature, they announced the discovery of the first preserved ancient DNA from Wallacea.

That discovery was of a far more complete human skeleton, a woman nicknamed Bessé, who lived on the island some 7,200 years ago, and was part of the mysterious Toalean cultural group who lived a secluded existence in Sulawesi’s forests for around 7,000 years. By some miracle, ancient DNA was extracted from Bessé’s inner ear bone, and the researchers were able to piece together her genetic ancestry, showing that she was related to the ancestors of Aboriginal Australians and Papuans, but also to a pre-Neolithic population who lived in the region, and who probably created the ancient cave art on Sulawesi.

So, Brumm says, it’s possible that the newly discovered jawbone could belong to an ancestral group linked to Bessé, but drawing that kind of definitive conclusion is as yet impossible.

“It could be that this individual we’ve now found is a part of the same population but that’s pure speculation and hope at this point,” he says.

It’s another tantalising instance of almost knowing something about these mysterious people, and Brumm believes that today’s mysteries will become tomorrow’s discoveries.

“When I first started my PhD in that part of the world, 2003, it was right at the beginning of this series of incredible discoveries that began with the Hobbit [H. floresiensis], now it’s extended to this bizarre new hominin from the Philippines, and then we have early cave art. It seems every few years something amazing comes out of this part of the world.

“Obviously I’m biased, but one of the most important parts of the early human story was playing out in that part of the world, and I think incredible, unimaginable discoveries are waiting for us in that region.”