Paris: Anthropologists on Wednesday said they had found the earliest engraving in human history on a fossilised mollusc shell some 500,000 years old, unearthed in colonial-era Indonesia.
The zigzag scratching, together with evidence that these shells were used as a tool, should prompt a rethink about the mysterious early human called Homo erectus, they said.
The discovery comes through new scrutiny of 166 freshwater mussel shells found at Trinil, on the banks of the Bengawan Solo river in East Java, where one of the most sensational finds in fossil-hunting was made.
It was here in 1891 that an adventurous Dutch palaeontologist, Eugene Dubois, found "Java Man."
With a couple of army sergeants and convict labour to do the digging, Dubois excavated part of a heavy-browed skull, a tooth and a thigh bone.
He interpreted these as being the remains of a gibbon-like hominid that was the long-sought "missing link" between apes and humans.
Dubois' claim excited fierce controversy, as well as jokey images of our distant ancestors as slack-jawed primates with dragging knuckles.
Palaeontologists eventually categorised the find as a Homo erectus, or "upright human" -- a hominid that according to sketchy and hugely debated fossil evidence lived from around 1.9 million years ago to about 150,000 years ago.
Reporting in the science journal Nature, a team led by Josephine Joordens at Leiden University in the Netherlands, harnessed 21st-century technology to take a new look at the Trinil shells, now housed in a local collection.
Carbon dating of sediment found in the shells put their age at between 430,000 and 540,000 years ago.
A third of the shells were also found to have a curious hole at the base of one of the bivalve's muscles.
Sharp-toothed animals such as otters, rats or monkeys may have bitten into it to get at the flesh -- but a likelier source, said the experts, is H. Erectus, which tucked into the shells for food.
The team carried out experiments on living mussels of the same mollusc family, Pseudodon, piercing the shell at the same location with a pointed object.
As soon as the shell was broached, the muscle was damaged by the tool tip and the mollusc could be easily opened without breakage.
The scientists then deployed a scanning electron microscope to get a closer look at the shells.
One of them was found to have a polished and smooth edge, suggesting it may have been used as a tool to cut or scrape.