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THE CARVED ISHANGO BONE
WHAT IS IT?

Among the millions of objects discovered at Ishango by Jean de Heinzelin’s team, some are more interesting than others. One in particular has been in the spotlight and become a star of African archaeology- the carved Ishango bone.

It is known as ‘the Ishango Bone’. It is an object made from a piece of quartz and a bone handle. Its structure alone makes it a remarkable object, as there are very few surviving prehistoric composite tools. The very fine quartz at one end could have been used for precise work, such as the ritual scarification of skin, for example. The bone handle has been narrowed, scraped, polished and engraved, so we can no longer tell what kind of bone it is, although we do know it belonged to a mammal.

What is so interesting about it?
Hypotheses The Ishango Bone’s handle is its claim to fame, because the decoration has been raising questions about its possible meaning since its discovery. The handle is carved with 168 parallel marks. These lines are positioned in groups of parallel lines split into columns on three sides of the handle.

Hypotheses
The Ishango Bone’s handle is its claim to fame, because the decoration has been raising questions about its possible meaning since its discovery. The handle is carved with 168 parallel marks. These lines are positioned in groups of parallel lines split into columns on three sides of the handle. Jean de Heinzelin established the hypothesis that this group of lines represented numbers. In several historic periods it was common to write numbers using lines. From there Heinzelin looked for a possible mathematical connection to link these different numbers. What he found led him to believe that the bone was proof of advanced mathematics, unprecedented for such an early period. Here are some observations and interpretations expressed by Jean de Heinzelin in his 1957 article on the Ishango site:

Central Column
The central column shows a number and its double: three and six, four and eight, five and ten, and two numbers that do not fit this pattern (five and seven).

Right Column
From this side the numbers could have a link with the number ten, a well-known number base. Therefore we have:

• 11 = 10 + 1 
• 21 = 20 + 1 
• 19 = 20 – 1 
• 9 = 10 - 1

Left Column
The Ishangoans would have known that eleven, thirteen, seventeen and nineteen are the prime numbers between ten and twenty. A prime number is a number that can only be divided by two numbers: itself and one.

-Other researchers have shared their interpretations of the marks:
The mathematicians Dirk Huylebrouk and Vladimir Pletser looked into Jean de Heinzelin’s ideas about number notation, and came to the conclusion that the bone was a kind of sliding scale which involved variations of the three and four base numbers, and by extension of base number twelve (3x4). However, they concluded that there was not enough proof to confirm an understanding of prime numbers.

Alexander Marshack, a Harvard archaeologist, also believes it is a system of number notation, but one which is related to the lunar calendar.

Olivier Keller, another mathematician, cautions against the temptation to project our modern culture of viewing numbers everywhere onto the bone. In his opinion, it is a habit that prevents the viewer from noticing other forms of symbols, those which are present in a range of media (on bones, stones and cave art) from the Upper Palaeolithic era and which also deserve a thorough investigation.

Interesting isn’t it?
Especially when you keep in mind that it’s 25,000 years old…
If one day one of the mathematical hypotheses is confirmed, it means that Palaeolithic humans already had a well-developed understanding of mathematics. This raises yet more questions: what did they use it for? Why did they mix several calculation bases? Was this knowledge shared among all of them? Was it used by fishermen?

Even today, the Ishango site still has not revealed all of its secrets; the Semliki Valley still hides other prehistoric sites. This region of Africa has been inhabited by Homo sapiens sapiens for at least 100,000 years. We still lack a lot of information to truly understand the ancient Ishangoans’ lifestyle, settlement and way of thinking.

Therefore, sooner or later, archaeologists must return to the banks of Lake Edward to complete the puzzle that was started in the fifties. No doubt, the missing pieces are still hidden in the ground…


Created By: Association pour la Diffusion de l’Information archéologique (ADIA)
Royal Belgian Institute of Natural Sciences (RBINS)