The Ishango tribe lived in Zaire in Africa around 9000BC, and may have been amongst the forefathers of modern African people. Out of all the many archaeological discoveries that have been made regarding the Ishango, perhaps the most significant is a small tool, made out of a bone handle with a chunk of quartz set into the end. It’s thought that the Ishango Bone was used for inscription of some sort – perhaps engraving, maybe even writing. That alone would make it fascinating.
The Ishango Bone
But the Ishango Bone contains three sets of numbers, in the forms of columns of scratches marked into its sides. Although there remains some academic uncertainty, it is thought that each of the three groups represents a depiction of the tribe’s knowledge of mathematical processes – astonishing, given the era. The first column is the plainest. There is a 3 next to a 6, a 4 next to an 8, and a 10 next to a 5, along with a further 5 and a 7. Leaving aside the last pair for the moment, these pairs clearly indicate multiplication by two.
What mathematical processes would you guess that the other two sides indicate, and where do the remaining 5 and 7 from the first side fit?
Update:
So. The Ishango Bone.
The second side represents the importance of 10 as a number, by omission. 9 and 11, at either end, bracket 10; and 19 and 21, in the centre, bracket 20. Remember that 10 and 20 are very natural human numbers of importance, given our digits. The third side is the most stunning. It gives 11, 13, 17 and 19 – the prime numbers between 10 and 20, in order. The remaining 7 and 5 on the first side extend the sequence of primes to include all the prime numbers below 20 occurring after 4… the first non-prime number.
Fun with prime numbers. The first prime numbers are 1, 2 and 3. 2 x 3 = 6. 2 x 2=4. 2 x 2 x 2=8. 8 + 2=10. 5 is the next prime number, and 5 x 2=10. 1, 2, 3, 5, 7, 11, 13, 17, 19. 3 x 3=9. 9 + 10=19, a prime number. 3 x 7=21. 21 – 10=11, a prime number.