Last seen two million years ago, one of the early stone tools discovered in Wonderwerk Cave.
Photo by M. Chazan
The earliest evidence for cave occupation by hominids has been discovered in South Africa.
Stone tools found at the bottom level of Wonderwerk Cave show that human ancestors were in the cave two million years ago, earlier than thought, according to an international research team led by Michael Chazan, director of the University of Toronto’s Archaeology Centre.
Geological evidence indicates that the tools were deposited in the cave by ancestors, not washed into the site from the outside, the team announced last week.
“There were a number of species of hominids in southern Africa two million years ago,” according to a University of Toronto news release. “The most likely candidate as the manufacturer of the stone tools found at Wonderwerk is Homo habilis.”
View of the Interior of Wonderwerk Cave
Photo by Royden Yates
The Wonderwerk Cave discoveries are close in age to the very earliest known stone tools and similar in date to the bottom levels at Olduvai Gorge, Tanzania, according to the release. The oldest known stone tools from sites in Ethiopia date to 2.4 million years.
To determine reliable dates for the age of the tools discovered in Wonderwerk Cave scientists used an unusual combination of tests.
Hagai Ron of the Hebrew University of Jerusalem took more than 50 small samples of soil from the cave where the tools were found. A method called paleomagnetic dating measured changes in the earth’s magnetic field across a sequence of samples to calculate the age of the soil around the tools.
Hagai Ron taking samples from the section at Wonderwerk Cave.
Photo by M. Chazan
Ari Matmon, also from the Hebrew University, took soil samples for a different test known as cosmogenic burial age. These samples were sent to an atomic accelerator in the United States where a procedure to measure isotopes, much like the method used in carbon dating, was carried out.
“The combination of stone tools indicating the presence of human ancestors and the dating of the level leads to the conclusion that human ancestors were in the cave two million years ago,” the University of Toronto’s Archaeology Centre stated.
Archaeological investigations of the Wonderwerk cave — a South African National Heritage site due to its role in discovering the human and environmental history of the area — began in the 1940s and research continues to this day.
The cave formed by water action in dolomite rocks more than two billion years old, some of the oldest rock on Earth. The age of the cave itself is not known.
Map of Wonderwerk Cave generated by 3-D scanning carried out by Heinz Ruther of the Department of Geomatics, University of Cape Town. The inset shows a view of the front excavation area where the dating project took place.