Dating techniques identify possible earliest evidence for cave occupation

This research could further our understanding of human biological and cultural evolution.

At Wonderwerk Cave, in South Africa’s Kalahari Desert, archaeologists have potentially identified evidence of the earliest cave occupation in the world, dating back to 1.8 million years ago, including some of the earliest signs of toolmaking, as well as the use of fire.

Wonderwerk Cave was first excavated in the 1940s. Its archaeological stratigraphy comprises evidence of human activity from the Early Stone Age in South Africa to the present day. 

According to a new paper, published in Quaternary Science Reviews, a team of researchers from the Hebrew University of Jerusalem (HU) and the University of Toronto used two different dating methods to determine the age of Oldowan tool industry at the cave, characterised by small sharp flakes, and to discover when it shifted towards Acheulean toolmaking, which saw the appearance of hand-axe manufacture.

The researchers took samples from a 2.5m-thick sedimentary layer which contained deposits of Stone Age botanical, faunal, and artefactual remains. A dating technique called palaeomagnetism was used, which involves analysing the magnetic signal of sediment particles. When dust was blown into the cave and formed a layer, as it settled, it preserved the direction of the earth’s magnetic field at that time.

Professor Ron Shaar of HU’s Institute of Earth Sciences taking samples for palaeomagnetism. Photo: Michael Chazan and the Wonderwerk Excavation Project.

The results indicate that Oldowan toolmaking in Wonderwerk Cave dates back to 1.8 million years ago, and that the Acheulean toolkit appeared one million years ago. Researchers also potentially identified one of earliest indications of intentional fire use ever found, as deposits containing burnt bone and ash in the Acheulean layer were dated to one million years ago.

The team used cosmogenic isotope burial dating to support their findings, which involves measuring the concentration of specific isotopes within sand particles, to deduce how much time has passed since they entered the dwelling.

According to the co-directors of the Wonderwerk Cave project, Professor Michael Chazan at the University of Toronto, and Liora Kolska Horwitz at HU’s National Natural History Collections, this evidence could be ‘an important step towards understanding the tempo of human evolution across the African continent’.