Credited to Democratic Republic of the Congo. Whether the notches record arithmetic, a lunar calendar or simply a grip is debated. Critics say the pattern claims rest on one bone, and older engraved bones are known from the Czech Republic and southern Africa.
How it began
The bone was made by people living at a lakeside fishing settlement at Ishango, on the Congolese bank of Lake Edward near the Semliki River, in what is now the Democratic Republic of the Congo. It is nearly 20,000 years old. Belgian geologist Jean de Heinzelin, working for the Belgian natural sciences institute, dug it out of the ground during excavations in 1950. Earlier estimates had put its age at between 8,500 and 11,000 years before the dating was revised.
How it works
The object is a dark brown curved bone about 10 centimeters long with a sharp piece of quartz fixed to one end. Along its length run three columns of notches, 168 in all, that appear to be grouped. On one side there are groups of three and six, four and eight, and five and ten. Two of the columns each add up to 60 and the third to 48. Because the bone was narrowed, scraped and polished, the animal it came from can no longer be identified.
Who pushed back
Readings of the bone have been contested since its discovery. De Heinzelin saw evidence of simple arithmetic, Alexander Marshack proposed a six-month lunar calendar, and Dirk Huylebrouck and Vladimir Pletser suggested a counting tool built on base 12. Skeptics answer that such analyses search for a pattern instead of testing one, that a second bone from the same layer shows no suggestive marks, and that the scratches might only have improved the grip.
What lasted
The bone became a standard reference point in discussions of how early people recorded quantities. It has been described as the oldest mathematical tool of humankind, although older engraved bones are known, including the roughly 26,000-year-old Wolf Bone from the Czech Republic and the roughly 42,000-year-old Lebombo bone from southern Africa.
Where it stands today
The bone is kept at the Royal Belgian Institute of Natural Sciences in Brussels, where visitors can study the notches through an interactive display. The museum presents it among the highlights of its 250 years of collecting. Mathematicians continue to publish new readings of its marks, including a study posted in 2025.
