The Earth of the last Ice Age (about 26,000 to 19,000 years ago) was very different from today’s world.
In the northern hemisphere, ice sheets up to 8 kilometres tall covered much of Europe, Asia and North America, while much of the southern hemisphere became drier as water was drawn into the northern glaciers.
As more and more water was transformed into ice, global sea levels dropped as much as 125 metres from where they are now, exposing land that had been under the ocean.
In southernmost Africa, receding coastlines exposed an area of the continental shelf known as the Palaeo-Agulhas Plain. At its maximum extent, it covered an area of about 36,000km² along the south coast of what’s now South Africa.
This now – extinct ecosystem was a highly productive landscape with abundant grasslands, wetlands, permanent water drainage systems, and seasonal flood plains. The Palaeo-Agulhas Plain was likely most similar to the present day Serengeti in east Africa. It would likely have been able to support large herds of migratory animals and the people who hunted them.
We now know more about how these people lived thanks to data from a new archaeological site called Knysna Eastern Heads Cave 1.
The site sits 23 metres above sea level on the southern coast of South Africa overlooking the Indian Ocean. You can watch whales from the site today, but during the Ice Age the ocean was nowhere to be seen. Instead, the site looked out over the vast grasslands; the coast was 75 kilometres away.
Archaeological investigation of the cave began in 2014, led by Naomi Cleghorn of the University of Texas. This work shows that humans have been using the site for much of the last 48,000 years or more. Occupations bridge the Middle to Later Stone Age transition, which occurred sometime between about 40,000 and 25,000 years ago in southern Africa.
That transition is a time period where we see dramatic changes in the technologies people were using, including changes in raw materials selected for making tools and a shift towards smaller tools. These changes are poorly understood due to a lack of sites with occupations dating to this time. Knysna Eastern Heads Cave 1 is the first site on the southern coast that provides a continuous occupational record near the end of the Pleistocene (Ice Age) and documents how life changed for people living on the edge of the Palaeo-Agulhas Plain.
Before the Ice Age, people there collected marine resources like shellfish when the coastline was close to the site. As the climate began to cool and sea levels dropped, they shifted their focus to land-based resources and game animals.
I am one of the archaeologists who have been working here. In a new study, my colleagues and I analysed stone tools from the cave that date to about 19,000 to 18,000 years ago, and discussed how the techniques used to make them hint at the ways that prehistoric people travelled, interacted, and shared their craft.
Based on this analysis, we think the cave may have been used as a temporary camp rather than a primary residence. And the similarity of the tools with those from other sites suggests people were connected over a huge region and shared ideas with each other, much like people do today.
Robberg technology of southern Africa
In human history, tools were invented in a succession of styles (“technologies” or “industries”), which can indicate the time and place where they were made and what they were used for.
The Robberg is one of southern Africa’s most distinctive and widespread stone tool technologies. Robberg tools – which we found at the Knysna site – are thought to be replaceable components in composite tools, perhaps as barbs set into arrow shafts, used to hunt the migratory herds on the Palaeo-Agulhas Plain.
We see the first appearance of Robberg technology in southern Africa near the peak of the last Ice Age around 26,000 years ago, and people continued producing these tools until around 12,000 years ago, when climate conditions were warmer.
Read more:
What stone tools found in southern tip of Africa tell us about the human story
The particular methods and order of operations that people used to make their tools is something that is taught and learned. If we see specific methods of stone tool production at multiple sites, it indicates that people were sharing ideas with one another.
Robberg occupations at Knysna date to between 21,000 and 15,000 years ago, when sea levels were at their lowest and the coastline far away.
The Robberg tools we recovered were primarily made from rocks that were available close to the site. Most of the tools were made from quartz, which creates very sharp edges but can break unpredictably. Production focused on bladelets, or small elongated tools, which may have been replaceable components in hunting weapons.
Some of the tools were made from a raw material called silcrete. People in South Africa were heat treating this material to improve its quality for tool production as early as 164,000 years ago. The silcrete tools at Knysna were heat treated before being brought to the site. This is only the second documented instance of the use of heat treatment in Robberg technology.
Silcrete is not available near Knysna. Most of the accessible deposits in the area are in the Outeniqua mountains, at least 50 kilometres inland. We’re not sure yet whether people using the Knysna site were travelling to these raw material sources themselves or trading with other groups.
Archaeological sites containing Robberg tools are found in South Africa, Lesotho and Eswatini, indicating a widespread adoption by people across southern Africa. The tools from the Knysna site share many characteristics with those from other sites, which suggests people were sharing information through social networks that may have spanned the entire width of the continent.
Read more:
65,000-year-old ‘stone Swiss Army knives’ show early humans had long-distance social networks
Yet there are other aspects that are unique to the Knysna site. Fewer tools are found in the more recent layers than in deeper layers, suggesting that people were using the site less frequently than they had previously. This may suggest that during the Ice Age the cave was used as a temporary camp rather than as a primary residential site.
Left with questions
Stone tools can only tell us so much. Was Knysna Eastern Heads Cave 1 a temporary camp? If so, what were they coming to the cave for? We need to combine what we learned from the stone tools with other data from the site to answer these questions.
Read more:
Ancient human DNA from a South African rock shelter sheds light on 10,000 years of history
Something we can say with confidence is that we have a very long and rich history as a species, and our innovative and social natures go back a lot further in time than most people realise. Humans living during the last Ice Age had complex technologies to solve their problems, made art and music, connected with people in other communities, and in some places even had pet dogs.
Despite the dramatic differences in the world around us, these Ice Age people were not very different from people living today.
Sara Watson works for the FIeld Museum of Natural History and Indiana State University
