The Ishango Bone

In 1960, Belgian geologist Jean de Heinzelin de Braucourt was excavating at Ishango, a site near Lake Edward in what is now the Democratic Republic of the Congo, when he uncovered a small bone tool with a quartz point at one end and a series of carefully grouped notch marks arranged in three columns along its surface. The groupings are what make this artifact extraordinary. Column (a) contains notches in groups that sum to 60, column (b) sums to 48, and the patterns within the groups suggest an awareness of prime numbers, doubling sequences, and possibly base-10 counting. For example, one column features the groups 11, 13, 17, and 19 — the prime numbers between 10 and 20. Now housed at the Royal Belgian Institute of Natural Sciences in Brussels, the Ishango Bone is widely regarded as the strongest evidence we have that prehistoric humans were engaging in genuine mathematical thinking — not just counting, but grouping, recognizing patterns, and possibly performing arithmetic. All of this was encoded in scratches on bone roughly 20,000 years ago. It is a powerful reminder that the human drive to find and record patterns in data is not a modern invention — it is tens of thousands of years old.