The Lebombo bone is a bone tool made of a baboon fibula with incised markings discovered in the Lebombo Mountains located between South Africa and Swaziland. Changes in the section of the notches indicate the use of different cutting edges, which the bone's discoverer, Peter Beaumont, views as evidence for their having been made, like other markings found all over the world, during participation in rituals.
The bone is between 44,200 and 43,000 years old, according to two dozen radiocarbon datings. This is far older than the Ishango bone with which it is sometimes confused. Other notched bones are 80,000 years old but it is unclear if the notches are merely decorative or if they bear a functional meaning.
According to The Universal Book of Mathematics the Lebombo bone's 29 notches suggest "it may have been used as a lunar phase counter, in which case African women may have been the first mathematicians, because keeping track of menstrual cycles requires a lunar calendar." But the bone is clearly broken at one end, so the 29 notches can only be a minimum number. Furthermore, in the many more notched bones since found there is no consistent notch tally, many being in the 1 - 10 range.