A team of Israeli and Canadian researchers has unearthed the world’s oldest home, dating back nearly 2 million years.
South Africa’s Wonderwerk (“Miracle” in Afrikaans) Cave is potentially the first cave in the world to be occupied by humans and contains evidence of both fire and tool use. The cave itself is one of the rare sites in the world that preserves a continuous archaeological record spanning millions of years.
“The site is very unique in that it was occupied throughout many different periods in prehistory through to historical periods, so it’s a wonderful archive of human activity,” Dr. Liora Kolska Horwitz, an affiliate researcher with the Hebrew University of Jerusalem’s National Natural History Collections, told The Media Line.
Together with Prof. Michael Chazan of the University of Toronto, Horwitz co-directed the Wonderwerk Cave excavations, which have been ongoing for the past 15 years. The cave is 140 meters (about 460 feet) long.
The research, which was recently published in Quaternary Science Reviews, was a joint effort between geologists and archaeologists. It confirms that our human ancestors were making simple Oldowan tools inside caves millions of years ago.
Oldowan is the oldest-known stone tool industry and considered to be a significant milestone in human evolutionary history. The earliest Oldowan tools are nearly 2.6 million years old and were found in East Africa; however, Wonderwerk Cave is unique among ancient Oldowan sites because it is a cave and not open-air.
“We’ve managed to establish now that the earliest occupation is an occupation associated with the Oldowan stone tool industry,” Horwitz explained. “They’re only found in open-air contexts and here we actually have Oldowan tools that people are making inside the cave at just under 2 million years.
“It’s the oldest cave home in the world,” she added.
Together with the Oldowan tools (mainly sharp flakes and primitive chopping tools), archaeologists also found animal bones inside the cave, which they hypothesize could point to one of the earliest examples of cooking. In addition, they were able to successfully determine the shift from Oldowan tools to early handaxes over 1 million years ago.
In yet another layer deep within the cave that is roughly 1 million years old, archaeologists discovered one of the earliest indications of fire use among prehistoric humans.
“We have the earliest evidence in the world for the use of fire inside a cave,” Horwitz affirmed. “It’s based on a repertoire of features: One of them is burnt bones, burnt stones, burt sediment or soil, and we also have intact ash.”
At the moment, researchers are unable to ascertain if the hominins occupying the cave were making and controlling the fire themselves or simply bringing it into the cave from burning branches found outside. Up until now, other examples of early fire use had only been found in open-air sites where the potential role of wildfires could not be excluded. In other words, the findings inside the cave point more strongly to the deliberate use of fire.
“Wonderwerk is the most robust set of data to support the use of fire around a million years ago,” she said.
Throughout the years-long excavations, one of the primary challenges the researchers faced was dating the cave deposits.
Dating methods for such ancient sites are less refined and much more complicated than radiocarbon dating, a process that can reliably measure things that are up to 50,000 years old. For this reason, the team relied on two innovative processes. Firstly, paleomagnetism, a geological method that determines the magnetization recorded in the ancient sediments that entered the cave. Secondly, they used cosmogenic burial dating, a new method that accurately date when particular sediments entered the cave.
For the paleomagnetism, the team carefully analyzed a 2.5-meter (8.2-foot) thick sedimentary layer using hundreds of samples from the cave walls to measure magnetic signals.
While compass needles today point northward, the earth’s magnetic field has shifted over time. Ancient particles, which entered the cave from outside before settling on the prehistoric floor, preserve the direction of the earth’s magnetic field at that time.
“These particles became aligned with the geomagnetic field because some of them act like tiny magnets, like compass needles that tend to align themselves with the ambient magnetic field,” Prof. Ron Shaar, of Hebrew University’s Institute of Earth Sciences, told The Media Line.
“They settle down in a preferred orientation determined by an ambient magnetic field,” he specified.
Shaar, a lead author of the study, specializes in dating geological materials. Because the exact timing of these magnetic “reversals” is globally recognized, he said, they provide clues to the entire sequence of layers inside the cave.
According to Horwitz, the discoveries at Wonderwerk Cave have important implications for our understanding of human evolution.
“It corroborates firstly that people [at the time] had the cognitive ability to make tools inside caves,” she stressed. “They had a broader repertoire than we thought before. The second thing is that the early date on fire is an enormous shift in human evolution.
“The moment you adopt pyrotechnology, it opens a world in terms of protecting yourself, [and] the kinds of food you can eat.”