Ishango bone

The Ishango bone, discovered at the "Fisherman Settlement" of Ishango in the Democratic Republic of the Congo, is a bone tool and possible mathematical device that dates to the Upper Paleolithic era. The curved bone is dark brown in color, about 10 centimeters in length, and features a sharp piece of quartz affixed to one end, perhaps for engraving. Because the bone has been narrowed, scraped, polished, and engraved to a certain extent, it is no longer possible to determine what animal the bone belonged to, although it is assumed to have been a mammal. The ordered engravings have led many to speculate about the meaning behind these marks, including interpretations involving mathematical significance or astrological relevance. It is thought by some to be a tally stick, as it features a series of marks that have been interpreted as tally marks carved in three columns running the length of the tool, although it has also been suggested that the scratches might have been to create a better grip on the handle or for some other non-mathematical reason. Others argue that the marks on the object are non-random and that it was likely a kind of counting tool and used to perform simple mathematical procedures. Other speculations include the engravings on the bone serving as a lunar calendar. Dating to 20,000 years before present, it has been described as "the oldest mathematical tool of humankind", although older engraved bones are also known, such as the approximately 26,000-year-old "Wolf Bone" from Dolni Vestonice in the Czech Republic, and the approximately 42,000-year-old Lebombo bone from southern Africa.