The Ishango bone, found in what is now the Democratic Republic of Congo, is a baboon leg bone notched in groups. Some researchers see prime numbers or a lunar calendar. Others say it is a simple tally.
Truth label: Debated. Serious people disagree. You get both sides.
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The patterns
One column holds 11, 13, 17 and 19 notches, the primes between 10 and 20. That might be chance.
A Moon calendar?
Another reading counts about six months of lunar phases.
Learn
- Counting is ancient. Whatever its purpose, it shows people were recording numbers long before writing.
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What is the Ishango bone made from?
A baboon bone. It is the fibula of a baboon.
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