Josephine Joordens, a biologist at Leiden University, found a seashell to have a zigzag engraving—a doodle—that was made by Homo erectus half a million years ago. The shell, which had sand grains still embedded in it, was collected in the 1890s by the Dutch paleontologist Eugène Dubois at a site in eastern Java called Trinil. While working a project on how H. erectus used marine resources, Joordens examined seashells and found some of them to have small perforations—a few millimeters wide—made with a sharp object. Closer observation revealed that the engraving was made intentionally by the maker to probably mark the shell as personal property or as art. The discovery of this doodle has raised speculations about H. erectus having abilities such as abstract thinking, which were attributed only to Homo sapiens.
Read more in Nature.