The world's oldest known engraved object may be an ochre pebble from Klasies River Cave in South Africa. The 100,000-year-old ochre pebble features what researchers believe are at least 23 engraved lines. It's possible that the design was a symbol that communicated something meaningful to prehistoric humans.
     "Associated human remains indicate that the engraved piece was certainly made by Homo sapiens," co-author Riaan Rifkin of the University of Witwatersrand's Institute for Human Evolution said. Rifkin and colleagues Francesco d'Errico and Renata Garcia Moreno performed extensive non-invasive analyses of the ochre pebble, which appears to have split off from a once larger piece. The scientists conclude that humans intentionally made the sub-parallel linear incisions on the object.
     "Upon engraving the piece with a sharp lithic implement, it is likely to have produced a markedly bright and dark red-maroon powder," Rifkin said. "The design may therefore have been strikingly visible shortly after it was produced."
     The Klasies River object measures close to 3 inches in length and contains a series of seven "deep broad engraved lines and several, about 16 or so, narrower and somewhat shallower linear features," Rifkin said. "The fragment is a remnant of a formerly semi-circular ochre pebble that likely contained a much more extensive engraved design on its surface." Of particular interest now is whether or not the engraver made the design with symbolic intent. Use of symbols and meaningful images is thought to have been a significant breakthrough in human development.
     Both linear and crosshatch engraved patterns may have been common thousands of years ago. Similar designs appear on engraved ochres from Blombos Cave, also in South Africa, and on ostrich eggshell fragments found in the Diepkloof Rock Shelter in the Western Cape Province. Some of these, and other, similar objects may even predate the Klasies River pebble, but studies on them are ongoing. "The employment of red ochre for symbolic purposes likely played an important role in mediating increasingly complex social relations that emerged during the Middle Stone Age," Rifkin explained.
     Christopher Henshilwood, a researcher at the University of Witwatersrand, did not work on this study, but he has examined other very early probable engravings. For example, he studied abstract markings of another piece of ochre dating to around 70,000 years ago. In that case, the engraving consisted of a more complex geometric pattern that looks like the letter 'X' repeated in a connected series. The possible meaning of these lines remains a mystery, "but they are symbols that I think could have been interpreted by those people as having meaning that would have been understood by others," Henshilwood said.

Edited from Discovery News (23 February 2012)