Lebombo Bone: One of the World's Oldest Counting Devices

The Lebombo bone is a small notched fragment of baboon fibula found in Border Cave in the Lebombo Mountains of southern Africa. Marked with 29 deliberate notches and dated to roughly 44,000-43,000 years ago, it is often called one of the oldest known counting devices. Whether its maker was really counting cannot be proven, but the object is a key piece of evidence for early record-keeping.

Border Cave

Border Cave is a large rock shelter high on the western cliff of the Lebombo Mountains, in KwaZulu-Natal province, South Africa, overlooking the border with Eswatini (formerly Swaziland). Its deposits, several metres deep, record human use of the cave across more than 200,000 years.

The cave was dug for fertiliser in the 1930s and then investigated by archaeologists. Its most extensive excavations were directed by Peter Beaumont in the 1970s, and the notched fibula was recovered in that period. Since 2015 a new team led by Lucinda Backwell, Francesco d’Errico and Lyn Wadley has reopened work there.

Border Cave is famous for organic remains that rarely survive elsewhere: grass bedding, wooden digging sticks, a lump of beeswax mixed with resin, and a stick that may carry traces of poison. In 2012 d’Errico and colleagues argued that several of these items resemble tools used by recent San hunter-gatherers, suggesting that elements of San material culture are very ancient.

The bone and its marks

The object is a fragment of the fibula, the thin lower leg bone, of a baboon. It is about 7.7 cm long and carries 29 parallel notches cut across one face. The notches were made with a stone edge and are clearly deliberate rather than butchery marks.

One end is broken, so the bone may originally have been longer and carried more notches. Microscope studies of notched bones from Border Cave have shown that some sets of marks were cut with different tools, possibly at different times. That pattern fits the idea of adding marks over a period, as a tally would require.

Tally, calendar or decoration?

The simplest interpretation is a tally: one notch for each item, day or event being recorded. Tally sticks were used by many societies until modern times, and San communities in Namibia are reported to have used notched sticks as calendars.

Because 29 is close to the length of a lunar month (about 29.5 days), some popular writers have called the Lebombo bone a lunar calendar, and occasionally a menstrual calendar. These ideas are attractive but cannot be tested. The broken end alone means the original number of notches is unknown, and notches can also be decorative or functional, for example to improve grip.

Tallying does not require a system of numbers or words for large quantities. A person can match one mark to one object, animal or day, and later compare the marks with what is in front of them. Many researchers regard this kind of one-to-one correspondence as an important step towards counting, because it turns a quantity into a lasting, visible record.

Dating

Early accounts gave an age of about 35,000 years, reflecting the radiocarbon dates available at the time. Later work combining radiocarbon with other methods placed the relevant layers at around 44,000-42,000 years ago, and the bone is now usually described as about 43,000 years old. This makes it around twice the age of the Ishango bone from central Africa, the other famous early notched bone.

Border Cave’s wider importance

The notched bone is only one of many remarkable finds from Border Cave. Human remains from the site include the burial of an infant accompanied by a perforated seashell, dated to around 74,000 years ago. Researchers have also reported layers of grass bedding around 200,000 years old and charred starchy plant roots, suggesting people were cooking such foods around 170,000 years ago.

Taken together, these finds make Border Cave one of the key sites for studying the long development of human behaviour in southern Africa. The notched bones belong to the later part of this record, when tools and ornaments similar to those of recent San communities began to appear.

Myths and facts

• Myth: it proves Stone Age people knew mathematics. It shows deliberate repeated marking, which is consistent with counting but does not demonstrate arithmetic.
• Myth: it is a proven lunar calendar. The lunar reading rests only on the number 29, and the bone is incomplete.
• Fact: it is not unique. Border Cave and other African and European sites have produced several notched bones, and older engraved objects such as the ochre from Blombos Cave show that people made deliberate marks long before.

Timeline

• c. 200,000+ years ago: People begin using Border Cave.
• c. 44,000-42,000 years ago: The layers containing the notched fibula are deposited.
• 1930s: Diggers remove deposits from Border Cave for fertiliser, exposing archaeological layers.
• 1970s: Peter Beaumont’s excavations recover the notched baboon fibula.
• 2012: d’Errico and colleagues publish a study of Border Cave’s organic artefacts, including notched bones.
• 2015: A new excavation programme begins at Border Cave.

Why it matters

The Lebombo bone is one of the earliest objects that may record information outside the human mind. Along with other finds from southern Africa, such as the engraved eggshell flasks of Diepkloof Rock Shelter, it shows early Homo sapiens using marks in structured, repeated ways tens of thousands of years before writing.