New research at a refuge on the edge of the Kalahari Desert in South Africa challenges the assumption that modern human origins and complex behaviors were limited to coastal environments. A collection of unusual artifacts that are more than 100,000 years old suggests that inside homo sapiens they were as innovative as their coastal cousins.
There is a widespread belief that the origins of modern humans and modern human cognition can be located in southern Africa. Since many of the archaeological sites related to early human activity are on the coast, experts assumed homo sapiens they also developed their symbolic and technological behavior in this region. But a new study published in the journal Nature paints a very different picture.
One of the stone tools excavated at Ga-Mohana Hill North Rockshelter. (Credit: Jayne Wilkins)
The oldest test for modern humans in the Kalahari Desert
An international team of scientists explored the Gash-Mohana Hill North Rockshelter, a site overlooking the savannah of the Kalahari Desert and more than 600 km (370 miles) inland. The study’s lead author, Dr Jayne Wilkins, of the Australian Research Center for Human Evolution at Griffith University, explained the importance of the discovery in a University of Innsbruck press release, saying :
“Our conclusions from this refuge show that overly simplified models are no longer acceptable for the origins of our species. Evidence suggests that many regions of the African continent participated, with the Kalahari being only one […] There have been very few well-preserved and dateable archaeological sites in the interior of southern Africa that can tell us the origins of homo sapiens far from the coast. A rock shelters on the hill of Ga-Mohana, which rises above an expansive savannah in the Kalahari, it is one of these places ”.
According to the press release, the work of scientists has also provided “the oldest evidence for modern humans in the Kalahari Desert in Africa.”
Archaeological excavations at Ga-Mohana Hill North Rockshelter were the first evidence of the complex homo sapiens behaviors were recovered. (Credit: Jayne Wilkins)
Looking at “Miniature Clocks”
An analysis of the site and the artifacts found in the rock refuge provides evidence that the behavior patterns of homo sapiens at the site it was parallel to what was happening on the coast 100,000 years ago. The main evidence comes from a collection of calcite crystals and ostrich eggshell fragments, which researchers believe could have been used as a container to store water.
Using optically stimulated luminescence (OSL), the team determined the age of the different archaeological layers in which the artifacts were found and dated the objects to 105,000 years old. Michael Meyer, head of the OSL laboratory at the Institute of Geology at the University of Innsbruck and a geologist who led the OSL analysis, explained the technique:
“This method exploits the signals of natural light that accumulate over time in sedimentary quartz grains and feldspars. You need to think of each grain as a miniaturized clock. Under controlled laboratory conditions we can read this natural light or the so-called luminescence signal, which in turn informs us of the age of the archaeological sediment layers. The more light the larger the sediment. ”
The researchers also noted that the climate of the Kalahari Desert used to be much wetter, as evidenced by the tuff formations (a type of limestone) that lie around the rock refuge. The dating of these features with uranium-thorium provides an age of between 110,000 and 100,000 years, the same time that ancient humans inhabited the site.
A collection of Kalahari crystals: symbols of a very ancient sacred palace?
At first, the collection of 22 calcite crystals presented a bit of a mystery because, unlike the ostrich shell pieces, researchers could not see any obvious utilitarian purpose for them. Then they decided that was a clue. Dr. Wilkins said, “Our analysis indicates that the crystals were not introduced into the deposits by natural processes, but were deliberately collected objects probably related to spiritual beliefs and rituals.”
Crystals collected before homo sapiens south of the Kalahari 105,000 years ago. (Credit: Jayne Wilkins)
The co-author of the study, Dr. Sechaba Maape, of the University of the Witwatersrand, agrees and said that “this is remarkable considering that the site is still used for ritual activities today.” The archeological team is aware of the fact that Ga-Mohana Hill is still of spiritual importance to the local communities and they claim that they are trying to limit its impact on the local use of the rock shelter site. “Leaving no visible traces and working with the local community is critical to the sustainability of the project,” noted Drs. Wilkins, that this is also important. Homo sapiens al Kalahari “.
The archaeological site of a rock refuge in the Kalahari Desert in South Africa. More than 100,000 years ago, people used the so-called Ga-Mohana Hill North Rockshelter for spiritual activities. (Credit: Jayne Wilkins)
The article, entitled “Innovative homo sapiens behaviors 105,000 years ago in a wetter Kalahari, ”it is published in the journal Nature.
Top image: A crystal of calcite is excavated from deposits more than 105,000 years ago in the northern refuge of Ga-Mohana Hill in the Kalahari Desert in South Africa. Source: Jayne Wilkins
By Alicia McDermott