A number line made of the body
Papua New Guinea has more than 800 languages, and its peoples have counted in a wide variety of ways: with fives, with twenties, with pairs, and in some places with the body itself. In a body-counting system, the words for numbers are the names of body parts, and counting means touching each part in a fixed order. The sequence is the body, and the last part touched tells the total.
The Oksapmin, who live in the mountains of the West Sepik region, are the people most often described in English-language accounts. They were studied in detail by the psychologist Geoffrey Saxe, who worked with them from the late 1970s and wrote about how they used the system and how it changed.
How the Oksapmin sequence goes
As usually described, a person starts at the thumb of one hand and moves through the fingers, then up the arm through the wrist, forearm, elbow and upper arm to the shoulder. The sequence continues across the neck and up to the ear, eye and nose. It then runs back down the other side of the body through the same parts in mirror order, ending at the little finger of the other hand. The total is 27 positions, with the nose at the fourteenth point, in the middle. The count of 27 works out because there are 13 positions on each side of the nose, and 13 plus 13 plus the nose itself is 27.
Each point has a name, and that name is the number. There is no separate abstract word for “fourteen”. If someone says the name of the eye on the right side, the listener understands both a body part and a position in the count. The word is therefore also close to what linguists call ordinal numbers, because it names where you are in a sequence as much as how many items have been counted.
To count a pile of objects, a person touches a body point for each object. To tell someone a number, they may name or touch the final point. A number above 27 can be handled by continuing round again or by combining the system with other words; reports differ on how this is done, and it is not a clean base 27.
Why it works, and what it cannot do easily
The great strength of body counting is that it needs nothing else. The tools are always present, the order is easy to remember, and the places are shared by everyone in the community. It also gives each number a physical location, which makes the sequence hard to forget.
The limits show up in arithmetic. Adding two quantities means moving along the body from one point by the other’s count, which is possible but unwieldy, and larger or exact calculations are tiring. Because the same point means both a body part and a number, ambiguity can arise: someone saying a body word may be naming the part, not counting. Context usually settles it.
Neighbours and parallels
Similar systems have been reported among other peoples in the same part of New Guinea, including groups speaking languages related to or near Oksapmin, though the points used and the number of them vary. Late nineteenth-century accounts of the Torres Strait Islands, between New Guinea and Australia, also describe counting by body parts. These reports come from outside observers, and the exact forms and extent of use are less clearly documented than the Oksapmin case.
Body counting is a cousin of the finger methods found elsewhere, such as the medieval finger reckoning of European monks. It differs in assigning names to larger body points, instead of using finger positions as signs for digits.
Change and survival
Reports describe the system changing as new tools arrived. Trade stores, a national currency and schools using written numerals gave people reasons to count and calculate in new ways, and Saxe documented how people adapted the body system to prices and money, sometimes with difficulty. Younger people educated in school may rely on written numerals and the national language’s number words, and the older sequence may be used less often.
This is a common story for traditional counting systems: they tend to survive for the tasks they suit and recede when new needs and tools appear. It does not mean the older method was inferior, only that a ruler marked in written numbers is better for some jobs than a thumb.
What it adds to the wider picture
Body counting is useful evidence for a broader point. People can count exactly without the long, regular list of number words that English speakers take for granted, because the sequence can be carried by something other than the voice. Researchers interested in languages with limited number words and in how number words develop keep returning to examples like this one, since it shows that the idea of a counting sequence can be physical.