Scientists find oldest evidence of ancient human activity deep in desert cave
The Cave of Wonders in South Africa is one of the few places on Earth where human activity can be continuously traced through millennia, and scientists have just established the oldest evidence of archaic human habitation in the cave: there is about 1.8 million years old.
It is based on an analysis of sedimentary layers containing animal bones, the remains of burning fires, and Oldowan Stone Tools: Objects made from simple rocks with chipped shards to sharpen them, representing what was once a significant advance in tool technology.
While tool artifacts at other sites were backdated 3.3 million years ago, the new findings are now believed to be the first sign of continued prehistoric human life within a cave – with the use of fire and tools in a fixed place inside.
“We can now say with certainty that our human ancestors made simple Oldowan stone tools inside the Wonderwerk cave 1.8 million years ago,” says geologist Ron Shaar of the Hebrew University of Jerusalem in Israel.
“Wonderwerk is unique among the ancient Oldowan sites, a type of tool first found 2.6 million years ago in East Africa, precisely because it is a cave and not an outdoor event. ”
While ancient evidence of forest fires and human fires may mix in outdoor sites, this is not the case in the Wonderwerk Cave. Additionally, other evidence of human fires has been found: burnt bones and ashes, for example, as well as tools.
The sediment sample examined in the new study was 2.5 meters (8.2 feet) thick, hominin activity in the cave over time. The layers were dated in two ways, first by paleomagnetism, by measuring the magnetic signal of the clay particles that had drifted into the cave.
These signals, trapped in time, show the direction of the Earth’s magnetic field in history. As the variation and inversion of this field through the centuries can be traced, scientists can date clay particles and whatever settles in them.
Second, the researchers used burial dating, an analysis of the radioactive decay of particles as they escape from the burst of cosmic radiation and are buried underground, or, in this case, inside. of a cave.
“Quartz particles in sand have a built-in geological clock that begins to run when they enter a cave”, says geologist Ari Matmon of the Hebrew University of Jerusalem.
“In our laboratory, we are able to measure the concentrations of specific isotopes in these particles and deduce how much time has passed since these grains of sand entered the cave.”
In addition to recording the use of Oldowan tools 1.8 million years ago, the team also spotted the transition to more complex hand axes (over a million years ago ) and the first deliberate use of fire (about 1 million years ago).
While exciting discoveries continue to be made around the world, very few places offer such a coherent record of the ancient comings and goings of man as the layers of sediment inside the Wonderwerk Cave – like the shows the new study.
“The precise ages of the Wonderwerk sediments are crucial to our understanding of the timing of critical events in the biological and cultural evolution of hominids in the region,” the researchers write in their published paper.
The research was published in Quaternary Science Examinations.