Human Evolution: An introduction
10mya - 12th millennia BCE
Humanity has made itself with many hands, through much turmoil. If we consider the whole timescale of hominin existence – back to quadrupedal, ape-like creatures all the way to the furless dominators of the planet – we can see the gradual accumulation of knowledge by succeeding species about the physical world in which they lived. Knowing the physical world in turn has allowed hominins and modern humans to manipulate it. “Nothing comes from nothing”, as the song goes. But what Rodgers and Hammerstein were reiterating was a profound philosophical and theological argument that has substantial scientific justification.
To establish how one species came to occupy the world and its spheres, interfering in interplanetary space and even outer space, I need to understand how that species first emerged and secured itself. The process of evolution is itself a form of accumulation. For most humans this remains a controversial proposition. Had I begun with pre-scientific explanations of human existence, I would have been acting ahistorically as the myriad mythologies, religions and philosophies postdate the physical presence of humanity. While scientific explanation is a recent invention, the physical reality of humanity is the oldest record we have. There is, in short, no sound way of circumventing the view that humans came long before all traditions. Indeed, as we will see, the mental ability to engage in complex language and symbolism are defining features of what makes us human.
Genomically, Homo sapiens is a mammalian species that emerged around 200,000 year ago (ya) on the African continent from which it spread to the rest of the earth’s landmass some 60kya. Palaeoanthropology tells us that when the new species spread, it did so into the territories of older hominins, including Homo erectus and Homo Neanderthalensis, which had also come from Africa. It was in Africa the human race and its predecessors (and relations) were able to genetically coalesce. To this day, the human populations on that continent are genetically more diverse than elsewhere. The same is true of language, with African languages having the highest number of phonemes.
The evidence supports the following claims: Humans emerged in modern-day Botswana around 200kya. For 100k years, the population of this new species grew slowly, although not in cultural complexity. Around 100kya, the first signs of symbolic thought are evinced at Blombos Cave with the use of iron oxide (red ochre) as a pigment for colouring shells. Symbolism is in full flight by 80-75kyrs at the same location, with geometric and representational art. The population had by then spread throughout Africa, driven by climate change. The last glacial period (the Ice Age) caused aridification as freshwater was locked up in ice closer to the poles. At around 60kya, there was an exodus of humans in eastern Africa which rapidly populated the Asian continent and major Oceanian islands (excluding New Zealand). Examples of symbolism in modern-day Indonesia date to 40kya, while in Europe, Aurignacian art dates to 35kya.
A helpful text by Ian Tattersall, Understanding Human Evolution (2022), explains the biology underpinning the key evolutionary moments for humanity. The dearth of evidence pertaining to human evolution arises in part because of the structural vulnerability of humans to the elements, with most finds being made in dark, dry, cool caves away from the equator. The fossil record generally is patchy, so Homo sapiens is not unique in having ‘missing links’. Another significant contributor to scarcity is climate change: where once there was fertile coast there is now sea; where there was rich forest there is now sand. What can be said is that hominins developed bipedality at least 4.4mya as forest turned into savannah. From here, the genus Australopithecus existed until 1.5mya. And it is here we can start to see how accumulation intensifies. For it was this genus that made the first stone tools, tamed fire and invented cooking, further encouraging brain growth and innovation to the point a new genus emerged: Homo.
I have divided the topic ‘human evolution’ into the following subtopics:
Toolmaking: Handwork
Cookery: The pivotal art
Language: The first youth subculture
Childhood: The long years
Shamanism: The first religion
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