New research at a rock shelter 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 over 100,000 years old suggests that inland 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 linked to early human activity are located on the coast, experts assumed that Homo sapiens its technological and symbolic behavior in that region also evolved. But a new study published in the journal Nature paints a very different picture.
One of the stone tools excavated from Ga-Mohana Hill North Rockshelter. (Credit: Jayne Wilkins)
The oldest evidence of modern humans in the Kalahari desert
An international team of scientists explored Ga-Mohana Hill North Rockshelter, a site overlooking the Kalahari desert savanna and more than 600 km (370 miles) inland. The study’s lead author, Dr. Jayne Wilkins of Griffith University’s Australian Research Center for Human Evolution, explained the significance of the discovery in a press release from the University of Innsbruck, saying:
“Our findings from this rock shelter show that oversimplified models for the origins of our species are no longer acceptable. Evidence suggests that many regions of the African continent were involved, with the Kalahari being only one […] There have been very few datable and well-preserved archaeological sites in the interior of southern Africa that can tell us about the origins of Homo sapiens offshore. TO rock shelter on Ga-Mohana hill, which sits on a vast savannah in the Kalahari, is one such site. ”
According to the press release, the scientists’ work has also provided “the oldest evidence for modern humans in the Kalahari desert in Africa.”
Archaeological excavations at Ga-Mohana Hill North Rockshelter where the first complex evidence Homo sapiens behaviors rebounded. (Credit: Jayne Wilkins)
Looking at “miniature clocks”
An analysis of the site and artifacts found in the rock shelter provides evidence that the behavior patterns of Homo sapiens at the site it paralleled 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 the researchers believe may have been used as a container for storing 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. Michael Meyer, head of the OSL Laboratory at the Institute of Geology at the University of Innsbruck and the geologist who led the OSL analysis, explained the technique:
“This method takes advantage of the natural light signals that accumulate over time in the sedimentary grains of quartz and feldspar. You have to think of each grain as a miniature clock. Under controlled laboratory conditions we can read this natural light or the so-called luminescent signal, which in turn informs us about the age of the archaeological sediment layers. The more light, the older the sediment. ”
The researchers also noted that the Kalahari desert climate used to be much more humid, as evidenced by the tuff (a type of limestone) formations found around the rock refuge. The uranium-thorium dating of these characteristics 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 some mystery because, unlike the ostrich shell pieces, the researchers could not see any obvious utilitarian purpose for them. So they decided it was a clue. Dr. Wilkins said: “Our analysis indicates that the crystals were not introduced into the deposits through natural processes, but were deliberately collected objects, probably related to spiritual beliefs and rituals.”
Crystals collected early Homo sapiens in southern Kalahari 105,000 years ago. (Credit: Jayne Wilkins)
Study co-author Dr Sechaba Maape of the University of the Witwatersrand agrees, saying “this is remarkable considering that the site is still used for ritualistic activities today.” The archaeological team is aware of the fact that Ga-Mohana Hill still has spiritual significance for local communities, and they say they are trying to limit its impact on the local use of the rock refuge site. “Leaving no visible traces and working with the local community is critical to the sustainability of the project,” noted Dr. Wilkins, that this is also important “So that Ga-Mohana Hill can continue to provide new insights into the origins and evolution of Homo sapiens in the Kalahari “.
The archaeological site in a rock shelter 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, titled “Innovative Homo sapiens behaviors 105,000 years ago in a more humid Kalahari ”, is published in the magazine Nature.
Top image: Calcite crystal excavated from 105,000-year-old deposits at Ga-Mohana Hill North Rockshelter in the Kalahari desert in South Africa. Source: Jayne Wilkins
By Alicia McDermott