Wim Lustenhouwer/VU University Amsterdam. A shell found on Java in the late 1800s was recently found to bear markings that seem to have been carved intentionally half a million years ago. The photograph is about 15 millimetres wide.

The engraved shell pictured come from a freshwater mussel species that were collected in the 1890s by the Dutch paleontologist Eugène Dubois, from Trinil. The first H. erectus calvarium was also found there. Duboid brough home many other artifacts as well and were stored away in Leiden, Netherlands.

Henk Caspers/Naturalis. The shell, from a freshwater mussel, shows a hole made by a member of Homo erectus.

Josephine Joordens from Leiden University opened these boxes to work on a project about marine life at Trinil, a site 80km insland. She found some perforations made with a sharp object suggesting someone used tools to crack these shells open. A visiting colleague photographed the shells and later noticed a faint zigzag pattern on one. “He sent me an email with a photo attached,” she recalls, “and he said, ‘Well, Josie, what do you think? What are we looking at here?’ And we looked at it and we thought, well, it’s kind of strange.”

After years of study, however, she says they concluded this: “It was not an animal, it was not something natural. It must have been a human.” And, she says, the carving is very old.

She says it resembles early geometric engravings found on ochre in Blombos Cave in South Africa, from around 100,000 years ago. Yet a couple of different techniques for dating sediments found in the Java shells show that this carving was made between 430,000 and 540,000 years ago.

“It’s at least four times as old,” says Joordens. “Also, we are not talking now about our own species, modern humans, but we are talking about Homo erectus, a species that’s older even than Neanderthals. It’s putting the origin of such engraving behavior a lot farther back in time.”

The full study can be found published on Nature here, “Homo erectus at Trinil on Java used shells for tool production and engraving.” What do you think this is — symbolic behavior like art or some early hominid evidence of food processing?