Ishango bone

What was discovered

Bone with notches grouped into three columns whose totals suggest doublings (3-6, 4-8) and the primes between 10 and 20 (11, 13, 17, 19). It is the oldest evidence of structured numerical grouping.

Its interpretation as a prime-number table or lunar calendar is speculative; many historians regard it simply as a counting tool.

What it led to

• grouped counting and elementary operations
• numeral systems
• arithmetic

Built on

• Tally stick (Lebombo bone)c. 43 ka
• Engraved lunar calendar (Abri Blanchard plaque)c. 32 ka
• tally marks

Made possible

• Lusona, Chokwe sand drawingsdocumentados desde el s. XIX (origen anterior)
• administrative record-keeping

Links

Sources✓ verified 2026-09-25

• https://en.wikipedia.org/wiki/Tally_stick
• https://arxiv.org/pdf/1204.1019