The ancient, big-bodied relatives of modern-day humans not only ate freshwater shellfish, but engraved their shells and used them as tools, a new study finds.
Researchers in Java, Indonesia, discovered engravings on a shell that dates to between 540,000 and 430,000 years ago. The ancient artwork could be the oldest known geometric carving made by a human ancestor, the researchers said.
It's unclear what the engraving a series of slashes and an "M"-shaped zigzag means, but it could indicate that Homo erectus, the ancestor of modern humans, may have been smarter than was previously thought.
The researchers studied 166 shells that were excavated in Java in the 1890s but are now stored at the Naturalis museum in the Netherlands. One of the shells has a smooth and polished edge, suggesting it may have been used as a tool for cutting or scraping.
Another shell, the one with the engraving, was likely carved with a sharp object, such as a shark tooth, the researchers said.