A team of paleoanthropologists from the Hebrew University of Jerusalem, CNRS and the University of Toronto has examined artifacts and sediments found in Wonderwerk Cave, a 140-m-long cave located in the eastern flanks of the Kuruman Hills, between the towns of Danielskuil and Kuruma, in the Northern Cape Province of South Africa.
“We can now say with confidence that our human ancestors were making simple Oldowan stone tools inside Wonderwerk Cave 1.8 million years ago,” said Professor Ron Shaar, a researcher in the Institute of Earth Sciences at the Hebrew University of Jerusalem.
“The cave is unique among ancient Oldowan sites, a tool-type first found 2.6 million years ago in East Africa, precisely because it is a cave and not an open-air occurrence.”
Professor Shaar and colleagues analyzed a 2.5-m thick sedimentary layer in Wonderwerk Cave that contained stone tools, animal remains and fire remnants.
“We carefully removed hundreds of tiny sediment samples from the cave walls and measured their magnetic signal,” Professor Shaar said.
Magnetization occurred when clay particles settled on the prehistoric cave floor, thereby preserving the direction of the Earth’s magnetic field at that time.
“Our lab analysis showed that some of the samples were magnetized to the south instead of the north, which is the direction of today’s magnetic field,” Professor Shaar said.
“Since the exact timing of these magnetic reversals is globally recognized, it gave us clues to the antiquity of the entire sequence of layers in the cave.”
“We relied on a secondary dating method to further confirm when the earliest humans may have occupied the site,” said Professor Ari Matmon, also from the Institute of Earth Sciences at the Hebrew University of Jerusalem.
“Quartz particles in sand have a built-in geological clock that starts ticking when they enter a cave.”
“In our lab, we are able to measure the concentrations of specific isotopes in those particles and deduce how much time had passed since those grains of sand entered the cave.”
The researchers were able to identify the shift from Oldowan tools — mainly sharp flakes and chopping tools — to early handaxes over one million years ago.
They were also able to date the deliberate use of fire by our prehistoric ancestors to one million years ago, in a layer deep inside Wonderwerk Cave.
The latter is a particularly significant because other examples of early fire use come from open-air sites where the possible role of wildfires cannot be excluded. Moreover, the cave contained a full array of fire remnants: burnt bone, sediment and tools as well as the presence of ash.
“The findings at Wonderwerk Cave are an important step towards understanding the tempo of human evolution across the African continent,” said Professor Michael Chazan from the Department of Anthropology at the University of Toronto and Dr. Liora Kolska Horwitz from the National Natural History Collections at the Hebrew University of Jerusalem.
“With a timescale firmly established for the cave, we can continue studying the connection between human evolution and climate change, and the evolution of our early human ancestors’ way of life.”
The results were published in the journal Quaternary Science Reviews.
Ron Shaar et al. 2021. Magnetostratigraphy and cosmogenic dating of Wonderwerk Cave: New constraints for the chronology of the South African Earlier Stone Age. Quaternary Science Reviews 259: 106907; doi: 10.1016/j.quascirev.2021.106907