On a rocky beach near Warrnambool, where the Hopkins River meets the sea, a layer of shells lies under ash from an extinct volcano, and soil accumulated over millennia.
The volcano – Tower Hill – exploded about 35,000 years ago. Underneath the ash, a calcarenite, or limestone, layer contains fragmented turban shells (Lunella undulata) that are still abundant in the nearby reef. The shells are also a traditional food source for the original owners of the land and sea, represented today by three local organisations – the Eastern Maar, Gunditj Mirring and Kuuyung Maar, who know the site as Moyjil.
For more than 10 years, a team of archaeologists, palaeontologists, geomorphologists and environmental scientists have been attempting to date the shells and the fire-blackened stones that lie alongside them in the limestone at Moyjil.
The most recent dating suggests the shells were gathered on the beach and smashed on rocks 120,000 years ago. If humans took part in that ancient feast, it will change what we know about their migration and settlement in Australia.
“We have to clear this up,” says Monash archaeology Professor Ian McNiven, who's been investigating Moyjil since 2012. “The potential story that could come out of this is huge. It could have global implications for humanity.”
Professor McNiven specialises in coastal sites and shell middens – accumulations of food remains (shells and bones), charcoal (from fireplaces) and stone tools left by Indigenous Australians.
Shell middens are common along the Australian coast. Earlier dating carried out in the 1990s at Moyjil found that the midden was 60-80,000 years old. That would make Moyjil the most ancient human site in Victoria. (Stone artefacts excavated at the site of Madjedbebe in Mirarr country, Kakadu National Park, have since shown that human occupation of northern Australia extends back at least to 65,000 years.)
But a more recent series of Moyjil tests conducted by the University of Adelaide using a method called optically stimulated luminescence show that the sand grains around the shells and fire traces had been buried for about 120,000 years. The results were published in Proceedings of the Royal Society of Victoria in March.
Professor McNiven explains that if the shells at Moyjil had been discarded 60,000 to 80,000 years ago, as he previously believed, they would have been gathered during the Ice Age. Sea levels were lower then, and the beach was more than 5km south of the present coastline. This strongly suggests the shells were carried to an inland camp, most likely by humans, he says.
But coastal mapping shows that 120,000 years ago – before the start of the last Ice Age – sea levels were about as high as they are today, and the beach at Moyjil was where it is now. This means the shell midden in the limestone could have been made by Pacific gulls. They're known to drop turban shells on rocks to release the meat – middens made by gulls and humans look alike.
But what caused the fire traces found near the shells?
Retired geomorphologist Professor Jim Bowler, formerly of the University of Melbourne, has also been exploring Moyjil. Like Professor McNiven, he was invited to investigate by environmental scientist Associated Professor John Sherwood from Deakin University. Professor Bowler is best known for uncovering Australia’s oldest human remains – 40,000 years old – at Lake Mungo, north of Mildura.
Professor Bowler also studied the ancient camp fires at Mungo. He believes Moyjil’s fire-blackened stones show evidence of human activity. The heat damage to the stones suggests they were exposed to temperatures more intense than a brush fire, which is the most likely type of bushfire on the coast. Cooking fires, on the other hand, would generate the necessary heat.
Professor McNiven isn't so sure. He says the stones, while intriguing, aren't enough for him to declare that humans made the Moyjil fires. At Lake Mungo, for instance, ancient stone artefacts were found around the camp sites. But 120,000-year-old artefacts haven't been seen at Moyjil – or anywhere else in Australia.
“The potential story that could come out of this is huge. It could have global implications for humanity.”
“The archaeological community, or at least the people that I've spoken to, don't believe there's enough evidence,” to say humans were there so long ago, he says. But he does believe the origins of the Moyjil fires “deserve more attention. So that's why we're moving into phase two now.”
The fire sites may be examined by a new method later this year. A proposal from geo-archaeologist Emeritus Professor Paul Goldberg from Boston University, who specialises in ancient fireplace sediments, is being considered by the Eastern Marr, Gunditjmirring and Kuuyung Marr organisations.
The traditional owners have been central to the Moyjil investigations that have taken place so far. Professor Goldberg will visit Australia in October. If the traditional owners agree, he'll take away samples from the Moyjil fire sites and examine them by microscope in Australia and in his Boston lab.
In 2018, the journal Science announced that 170,000 to 190,000-year-old human bones and stone artefacts were discovered in a cave in Israel – they're the oldest modern human remains yet found outside of Africa.