By Mick D’Alton
If you had owned a property on Agulhas Heights about 12 000 years ago, you would have been disappointed to find that you could not see the ocean from your front porch. That’s because the coastline was anything from 50 to 100 km south of where it is today, roughly along the outer edge of the present day Agulhas Bank.
But you would not have been faced by a vista of dried out seabed as one is accustomed to during spring low tide, but a vast fertile plain inhabited by an array of wild animals and
birds, many that you would recognise and some that are now extinct.
This was the PalaeoAgulhas Plain (PAP).
The Palaeolithic Period covers the time from 2,5 million years ago to about 10 000 years BCE which was also the middle stone-age period. The graph below shows how during the last 300 000 years the glacial cycles (ice ages) have occurred three times for periods of about 50 000 to 70 000 years each.
The sea levels receded as the moisture in the atmosphere was captured in glaciers and ice caps across the higher interiors of the world’s continents and new land was exposed. In the intervening periods between the glacial cycles and which were of roughly the same duration, the sea rose covering the PAP, and the coastline then lay more or less where it is today.
With each successive glacial cycle, the warm Agulhas current lessened the effects of the cold interior creating a mild climate with ample rain on the PAP. The land was cleansed and seeds were brought down with the flowing waters from the higher interior. In time the PAP became a fertile land of grass and wetlands with heavily wooded rivers and streams interspersed by large vleis.
Moving south to the Agulhas Plain
Scientists have described it as similar to the lowlands associated with the Kars, Heuningnes and Nuwejaars Rivers of today but with a much higher proportion of edible grasses. As the exposed land was being rejuvenated, the interior became colder, driving all the inhabitants of the continent south to warmer climes where vast new grazing fields were opening up, and soon the PAP was like a Serengeti of the south.
Like the animals, early humans also moved away from the cold and soon found the PAP, which was in their terms a land of milk and honey. The diverse and productive coastline provided shellfish and fish, bulbs and berries were plentiful in the surrounding vegetation and the large number of both big and small antelope encouraged the innovation of hunting methods and equipment.
And so it is thought that modern humans, Homo sapiens, evolved on our coastline from a tiny founder population that migrated into the rest of Africa and then, between 40 and 45 000 years ago into Eurasia, and from there to the Americas.
The tales told by diggings and fossils
These first inhabitants sheltered under rock overhangs and in caves where diggings have now revealed mammal remains. Coupled with fossil track sites, these show that at times, a large number of both extinct and extant mammals roamed the PAP during the last 400 000 years.
Animals such as the now extinct giant buffalo and giant zebra, as well as Cape buffalo, eland, kudu, black and white rhinoceros, black wildebeest, hartebeest, roan antelope, common reedbuck and even elephant and giraffe have left their mark. Not surprisingly blue antelope, quagga and bontebok were present and it is assumed that the plains zebra and blesbok were also amongst those fossils though not able to be separated from their close cousins.
As the sea levels rose and slowly covered the PAP during inter glacial periods, people and animals were forced to retreat before the rising water, some becoming trapped in the coastal strip now known as the Overberg. Isolated from the interior by the Cape Fold Mountains, the dry Little Karoo and the North Cape and Tankwa Karoo systems, they were forced to adapt to the vegetation of the Cape Floristic Region (CFR) which is generally of low nutrient value and unpalatable.
Within the CFR the smaller antelope such as steenbok and Cape grysbok were well established and persisted through the climate cycles, specialising in browsing the succulent leaves and tips of the fynbos. Fossils of these antelopes have been found at sites dating from 400 000 years ago. Of the many larger mammals that may have been trapped, only the bontebok, quagga and blue antelope were able to adapt, changing in habit and form to suit the conditions and utilising the grassy renosterveld to the full.
How stock led to change
Indigenous farmers from the north started to inhabit the area from about 2000 years ago, bringing with them their domesticated stock and being far less selective in their grazing requirements, competition for the scarce seasonal grass began.
Persecution by the herders of the wild animals trying to access this grass and overgrazing by the stock would have escalated dramatically with the arrival of the colonists and their firearms, and the competing herds of wild animals were either killed or forced into areas less able to sustain them. And so the domination of the scarce grasslands by domestic stock, the persecution of the competing wild herds by the herders and the very limited grazing value of the remaining fynbos drove the wild herds to collapse.
By the start of 1800 the blue antelope was already extinct. The quagga probably followed about 50 years later while the bontebok was saved from extinction by a few dedicated Bredasdorp farmers in the early 1900s.
References
The majority of the information included in this document has been drawn from papers and books by others listed below:
- Venter, J.A. , Brooke, C.F., Marean, C.W., Herve, F., Helm, C.W., (2019) Large mammals of the Palaeo-Agulhas Plain showed resilience to extreme climate change but vulnerability to modern human impacts.
- Marean, C., Cowling, R.M., Franklin, J. (2019) The Palaeo-Agulhas Plain: Temporal and Spatial Variation in an Extraordinary Extinct Ecosystem of the Pleistocene of the Cape Floristic Region
- Cowling, R.M., Potts, A.J., Franklin, J., Midgley, G.F., Engelbrecht, F., Marean, C.W., (2019) Describing a drowned Pleistocene ecosystem: Last Glacial Maximum vegetation reconstruction of the Palaeo-Agulhas Plain.
