with grid or cross-hatch patterns, dated to some 70,000 years ago. This suggested to some researchers that early Homo sapiens were capable of abstraction and production of abstract art or symbolic art. Also discovered at the Blombos cave were shell beads, also dating to c. 70,000 years ago. Engraved ochre has also been reported from other Middle Stone Age sites, such as Klein Kliphuis, Wonderwerk Cave and Klasies River Cave 1. Arguably, these engraved pieces of ochre represent – together with the engraved ostrich egg shells from Diepkloof – the earliest forms of abstract representation and conventional design tradition hitherto recorded. The interpretation of the hatching patterns as "symbolic" has been challenged, and several purely functional explanations of the objects have been proposed, e.g. as an ingredient in mastic, skin protection against sun or insects, as soft-hammers for delicate knapping, as a hide preservative or as medicine. The Blombos Cave cross-hatches, dated to as early as 73,000 years old, have been described as "abstract drawings" in a 2018 publication. Claimed Lower Paleolithic art A 500,000-year-old Pseudodon shell DUB1006-fL found in Java in the 1890s, associated with Homo erectus, contains the earliest known geometric engravings. Although some commentators express an opinion that this could be the earliest evidence of artistic expression of hominids, the actual meaning and intent behind these engravings are not known. Homo erectus had long before produced seemingly aimless patterns on artifacts such as is those found at Bilzingsleben in Thuringia. Some have attempted to interpret these as a precursor to art, allegedly revealing the intent of the maker to decorate and fashion. The symmetry and attention given to the shape of a tool has led authors to controversially argue Acheulean hand axes as artistic expressions. There are several other claims of Lower Paleolithic art, namely the "Venus of Tan-Tan" (before 300 kya) and the "Venus of Berekhat Ram" (250 kya). Both of these may be natural rock formations with an incidental likeness to the human form, but some scholars have suggested that they exhibit traces of pigments or carving intended to further accentuate the human-like form. See also Prehistoric art Art of the Upper Paleolithic List of Stone Age art Behavioral modernity Origin of language Origin of music Prehistoric religion References Middle Stone Age Middle Paleolithic