Out of this World and into the Next — how life began on Earth, and how human civilisation will expand beyond it

Daily Maverick

5 days ago

A theoretical physicist's grand tour of how life emerged on Earth and how human civilisation will begin expanding beyond our home planet​.
In Out of this World and into the Next, theoretical physicist Adriana Marais explores the discoveries that lie beyond our world. This extract reflects on the origins of human exploration, particularly space exploration and how it can be traced back to early technological advancements in South Africa.
Explorers
The day cosmonaut Yuri Gagarin bravely hurtled around Earth in the first ever craft to take a human into Earth orbit was arguably the beginning of human space exploration. Going back even further, however, palaeo­anthropologist Francis Thackeray, former director of the Institute for Human Evolution in Johannesburg, makes the case that the first steps towards space exploration were taken right here in my home country, South Africa. Here there are multiple cave sites that have been exca­vated by archaeologists for about 100 years, generating a range of insights into human prehistory. For example, the controlled use of fire was inferred from burnt bones discovered at Swartkrans in the Cradle of Humankind World Heritage Site. The bones had been heated to tem­peratures higher than that of naturally occurring grass fires. Other evidence was obtained at Wonderwerk cave, 30 metres in from the entrance. The fires were proba­bly used in the same place, over and over again. The people responsible were possibly of the species Homo erectus, the first human ancestor to spread from Africa throughout Eurasia, existing between around 2 million years ago up until about 300,000 years before present. Evidence of the controlled use of fire at least 1 million years ago, in Africa, is the earliest technological precur­sor to rocket propulsion. Wonderwerk means miracle in Afrikaans.
Our origins: forged in fire
During the COVID-19 pandemic lockdown of 2020, my partner at the time, Kurdt Greenwood, and I built a cabin deep down in a valley in the ancient indigenous Tsitsikamma forest. We lived there over the first half-year of lockdown, the only access being a 1.2-kilometre rugged footpath down a 300-metre descent and across a river, the route the two of us carried down a couple of tonnes of supplies to build the cabin. It was a time to contemplate resources, the most important of these being shelter, power, water and food; if we did not collect kindling from the upper slopes of the valley during sun­shine, during rain, we would have no hot water or cooked food. Collecting water and driftwood from the river, and medicinal plants in what appeared to be ancient terraced north-facing gardens above our cabin, I had the feeling of being part of a long lineage of humans living beside this ancient stream.
We spent a lot of time exploring the area, and one day Kurdt discovered a collection of seashells in the compacted ground under a rock overhang beside the river. This is around 13 kilometres, or a six-hour trek, upstream from the coast where, at the river mouth, one of the largest shell midden deposits on the planet is located in a rock shelter; home to the earliest people of Southern Africa, the San, for over 12,000 years, and a place I've been visiting with my dad to look for stone tools since I was a child. A collection of seashells in compacted ground so far from the coast could mean just one thing.
We returned to the site about a kilometre upstream from our cabin the next day with brushes and buckets and started digging. Kurdt's hole revealed pebbles carved into fishing sinkers and long bone hooks, stone cutting blades and smooth grinding rocks. As a survival expert and animal behaviourist, he was hopping with excite­ment, theorising that the tool maker fished for eel in the deep pockets of the river, and immediately planned to try the technique himself.
The hole I dug right next to his contained nothing at all, so I stepped back to look around. I was drawn to the very back of the overhang, where some fine, dry sand lay in the shadow. I crouched under the overhang and brushed away slowly at the surface. I found a piece of an old bottle, then a pottery shard, then beneath that a collection of crystals and small animal bones, and then suddenly a round, hard shape appeared. A sense of gravity fell upon me. Even as we discussed whether it was a stone, a bulb, a baboon skull … I knew it was someone's story we were uncovering, a voice that had last spoken thousands of years ago, in another time. We alerted local archaeologists, who confirmed from the tools with the skeleton, as well as the position in which the body was laid to rest facing east, that it is a San burial site. We await the dating of the site, which could be any­thing between a couple of hundred to tens of thousands of years old.
The night of the discovery, the forest was so close as I closed my eyes to sleep; the deep, damp stillness of the trees, the gurgle of the stream over the rocks, which often sounded like women and children laughing upstream, as they had done in this valley for at least 10,000 years. With some trepidation, I asked that the person whose remains we had uncovered, if unhappy about us doing so, would come to me and let me know. I fell uneasily asleep into a strangely clear dream: I saw a time-lapse of layers of atoms and molecules accumulating through life and weather on the surface of the Earth; I saw that the person who had once lived in this body was no longer attached to the layers of matter left behind. I was told that I was free to sift through this record of what was, if I so desired. I felt more at ease for the rest of our excava­tion. While so much has changed since this person last roamed the Earth, holding the tools that they used to navigate this same environment so long ago, I felt the unity of all humanity through the ages; a continuity in the story of who we are. DM