Updated: Dec 7, 2020
Deep, dark secrets entombed on Table Mountain.
During the last 50,000 years, following the expansion of modern humans across much of the world, somewhere between 109 and 120 billion people have been born into life. That’s an awful lot of people that have walked this planet. As of this evening, 25 April 2020, an estimated 7,780,216,354 souls are supposedly alive, although we can’t be sure how many of 'us' are truly conscious.
Human population numbers have waxed and waned over time but have been growing exponentially over the past 150 years (following the eradication of infectious diseases and supported by medical advancements and industrialized agriculture).
It wasn’t always so.
There have been times in our past when human populations have plummeted to levels perilously close to extinction.
Sometime around 80,000 – 100,000 years ago – at the time when modern humans were well established in Africa and beginning to permeate into Eurasia in small groups of pioneering populations - something dramatic happened (a volcano, disease, climate change…) which caused a sudden dramatic decline of people especially in sub-Saharan Africa. Some estimates, based on genetic studies, suggest that from an estimated global population of 1.5 million, fewer than 2,000 survived. The notion of a “biblical Eve” has gained traction in the scientific community, especially among geneticists, who purport, based on the analysis of mitochondrial DNA, that the entire population of the planet today can trace its ancestry back to a handful of women, perhaps even just ONE woman, who lived in southern Africa.
But I digress…
Along an inaccessible ridge-line high-up on Table Mountain is an unusual cave like none other. It extends deep into the mountain for some 20 metres and has a long depositional history. The location is a closely guarded secret (to preserve its scientific integrity). In 1989 I was part of an interdisciplinary team that excavated and analysed the sediments from a ‘pillar box’ (1m x 1m) excavation down to bedrock that took place in this cave under the auspices of UCT’s archaeology department. My work revealed a crude but fascinating record of depositional history and some trends in vegetation and climate change over many 1000’s of years on Table Mountain, since the last Ice Age.
But what was most fascinating for me (and which remains an enigma), was the discovery that this cave had been frequently used, or had been inhabited, by people associated with the Middle Stone Age.
At the time we conducted our research, we were unable to accurately date the older layers associated with the archaeological remains. We were in effect ‘beyond the limits’ of conventional radiocarbon dating techniques at the time. But we can infer a few things. We know with some certainty that these old layers are more than 30,000 years old based on the limits of C14 dating. We can also infer, based on the stone tool assemblages (from dated layers elsewhere) that the stone tools we uncovered here closely resemble derivatives of the stone tools found at Howieson’s Poort which are classical Middle Stone Age artifacts dating to 50 - 70,000 + years old.
So, what we can deduce is that people (our modern human ancestors) were either living in this cave or frequenting it (perhaps for ritual reasons) for thousands of years somewhere between 70,000+ – 50,000 years ago.
Then something happened.
All evidence of human occupation disappears. In a cloud of ash. Gone forever.
A sudden, perhaps dramatic, event occurred – we can see it in the sedimentology. A clearly defined lens of ash arrived in the cave sediments and all evidence of human occupation ceases from that point onward. There is no evidence that people ever visited this cave again (until it was inadvertently 'discovered' in the 1920s).
There are many theories that have been put forward to account for the rapid and inexplicable population decline in Africa during the last inter-glacial. For many years it was attributed to the volcanic eruption of Mt Toba in Indonesia (circa 75,000 years ago) which plunged the earth into a nuclear winter – but the impact of Toba has been downplayed in recent years. More recent theories include climate change and perhaps even disease. Who really knows? In time, these secrets may be revealed.
For now, I take heart from the fact that as a species we’ve encountered repeated obstacles in our evolutionary history - and we've survived (albeit just, in some instances).
I can’t wait to be able to visit the cave of our ancestors again - and to sit in reverence and to be grateful for my life.