This woman is displaying the Oksapmin 27-body part counting system (see figure at left). In the video, you will see her enumerate body part names beginning with the thumb on one hand (1) proceeding up to the nose (14) and down to the little finger on the other side of her body (27). At the end of the count, as has been standard practice, she exclaims a fists raised "tit fu!", indicating that she's completed all of the body parts of the system.* Similar 27-body part systems have been used traditionally throughout the larger Mountain-Ok region of central New Guinea (see map below). Note the direction of the count is arbitrary and meaning is linked to the act -- the woman is using a right-to-left trajectory whereas the upper left schematic shows the opposite direction. Traditionally, if people need to count beyond the 27th body part, they loop back to tan dopa (28), or the wrist on the other side (28th position).
Traditional uses of the system did not involve arithmetical functions. With the introduction of currency and people's engagement with economic exchanges with currency in tradestores, some Oksapmin people elaborated arithmetical functions for the system. To observe a tradestore owner using the body system to accomplish an arithmetical problem, go to the following link: Oksapmin tradestore owner solving 16-7=?
Schooling was another context in which Oksapmin elaborated arithmetical functions for the system. To observe a fourth grader constructing an arithmetical function for the body system, go to the following link: fourth grader solving 16-7=?
*Although the woman labels every body part with its appropriate body part name, she inadvertantly skips one body part in the system - tan kata (18). Tan kata (18) means shoulder-on-the-other-side (or the 18th position)).