Israeli scholars find millions-year-old human traces in ‘Miracle’ Cave

Written by on April 26, 2021

A group of scholars from the Hebrew University of Jerusalem and the University of Toronto have unearthed traces of human activities dating back to millions of years in the Wonderwerk Cave in South Africa’s Kalahari Desert. Their findings were published in the May issue of the Quaternary Science Reviews.

The cave, whose name means ‘miracle’ in the Afrikaans language, offers some of the earliest evidence of use of fire and tool production.

The new study employed paleomagnetism and burial dating to scan some 2.5-meter thick sedimentary layer containing ashes, remains of animals, tools and fires.

“We can now say with confidence that our human ancestors were making simple Oldowan stone tools inside the Wonderwerk Cave 1.8 million years ago,” the lead author of the paper Professor Ron Shaar at HU’s Institute of Earth Sciences explained in a press release.

Wonderwerk Cave in South Africa. (Credit of Michael Chazan)Wonderwerk Cave in South Africa. (Credit of Michael Chazan)

Oldowans are the oldest tools produced by humans, usually consisting in crudely worked chopping tools chipped in two directions.

“Wonderwerk 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,” Shaar added.

Attributing traces of fires in open-air environments to human activity is more challenging because the influence of natural wildfires cannot be ruled off with certainty.

Paleomagnetism is the study magnetic rocks and sediments to document the history of the earth’s magnetic field, whose implications space from climate change to navigation systems.

When objects containing magnetic minerals burn at a very high temperature, those minerals are re-magnetized and therefore record the direction and the magnitude of the field in that precise moment.

While currently and in modern history the direction of the earth’s magnetic field has been associated to the geographic north, in the past it is known to have been completely neutral or even pointing south.

“We carefully removed hundreds of tiny sediment samples from the cave walls and measured their magnetic signal,” Shaar said. “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.  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.”

The remains offered testimonies of the first deliberate use of fire and production of more sophisticated tools – hand axes – about one million years ago.

They were also analyzed according to a second method to confirm the results.

“Quartz particles in sand have a built-in geological clock that starts ticking when they enter a cave,” Prof. Ari Matmon, Director of HU’s the Institute of Earth Sciences explained. “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 findings of the study have far-reaching implications to understand more about not only the vicissitudes of Wonderwerk Cave and ancient human evolution, but also present-day challenges.

“With a timescale firmly established for Wonderwerk Cave, we can continue studying the connection between human evolution and climate change, and the evolution of our early human ancestors’ way of life,” concluded Prof. Michael Chazan at the University of Toronto and Liora Kolska Horwitz at HU’s National Natural History Collections.

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