Mysterious Origins – What we don’t know about the emergence of humans
We humans are such a clever species. Our spaceships have landed on the moon and Mars. We have discovered life forms ten kilometers underground and in deep-sea fumaroles. Our geneticists have sequenced over 200 genomes, while our astronomers have discovered earth-like planets on the edge of space-time. We’ve speculated on the extinction of the dinosaurs, and now physicists at the Large Hadron Collider are close to unraveling the secrets of quantum mechanics.
And yet, when it comes to ourselves, there’s an awful lot we don’t understand. The brain for example. And how we became human.
Science writer Carl Zimmer wrote in 2003 that, “what we don’t know about our evolution vastly outweighs what we do know.”
Three main aspects of human evolution continue to frustrate scientists:
- The abrupt transformation—from African hominid to modern human about 46,000 years ago
- Physiology—why, despite sharing 99 percent of our protein-coding genes with chimps, do we look so different?
- Human nature—where did all the unique behaviours that distinguish us from other primates come from?
Let’s begin with the mysterious speciation event that suddenly created modern humans. “Few topics in palaeoanthropology”, Cambridge University Professor of Archaeology and Human Evolution Paul Mellars observed in 2005, “have generated more recent debate than the nature and causes of the remarkable transformation in human behavioral patterns that marked the transition from the Middle to the Upper Palaeolithic era in Europe.”
MIDDLE PALAEOLITHIC AND UPPER PALAEOLITHIC: These terms refer to different stages of human evolution. The Middle Palaeolithic denotes archaic humans and hominids, a period before art, culture, symbolic language etc.—in short, the time before we were ‘us’. Upper Palaeolithic refers to the new ‘smart’ homo sapiens —with a more sophisticated tool kit, representational art, symbolic language and creativity.
Although archaic hominids like Homo heidelbergensis had brains as big as ours 600,000 years ago, they never produced art, culture, complex language, symbolic thinking or any of the other tangible indicators of human capacity. This flowering of modern humanity has been described as ‘the human revolution’, the ‘dawn of human culture’, and the ‘explosion of human capacity’, but there is still no agreement on what precipitated it or why.
Excavated from a Middle Stone Age cave in South Africa, the 77,000 year-old block of red ochre (left) has been described as the earliest discovered art work. However, true representational art, like the magnificent horse from the Lascaux cave in France (right), did not appear until around 30,000 years ago.
It is a commonly held misconception that the Upper Palaeolithic revolution began in Africa. What the latest evidence shows is that a few isolated early examples of modern human behaviour did appear in Africa as early as 300,000 years ago4 including what may be an example of 77,000 year old art5. But none of these isolated flowerings of Initial Upper Palaeolithic culture ever ‘took off ’ on a grand scale across the continent, much less across the globe. While a few isolated tribes made shell beads, others did not. While most of them fashioned crude tools, a small number made more efficient ones. And a few appeared to have used ochre (presumably for decoration) while others did not.
In November 2008, geologist Zenobia Jacobs, from the University of Wollongong in Australia, reported in the journal Science that two such Initial Upper Palaeolithic cultures flourished for only a few thousand years before disappearing. One group (the Still Bay culture ) emerged around 72,000 years ago but vanished about 1000 years later. The second (the Howieson’s Poort culture ) emerged about 65,000 years ago but lasted only 5000 years.
Jacobs notes that, “this burst of innovation ended about 60,000 years ago, returning to a further 30,000 years of relatively crude stone-age technology."
Making shell beads like these from the Blombos cave in South Africa is generally considered a sign of modern behaviour, but the people who made them disappeared about 60,000 years ago. Photo: Chris Henshilwood and Francesco d'Errico.
The fact that these early African Upper Palaeolithic cultures were sporadic and short-lived came as a surprise to many anthropologists because it was assumed that Upper Palaeolithic culture would have spread like wild- fire as a result of an increase in hunting and gathering yields. This turned out not to be the case. Data from both the Middle and Upper Palaeolithic reveal quite convincingly that there was actually no significant difference in hunting effectiveness between the two eras.
This may seem odd because Upper Palaeolithic culture is now so indispensable to our modern lives that we can’t imagine life without it. Yet we need to remember that archaic humans had survived more than six million years (since diverging from the primate order)11 without Upper Palaeolithic culture.
That is not to say the transition to the Upper Palaeolithic didn’t result in minor increases in survival and reproductive rates. But while the acquisition of some Upper Palaeolithic behaviours in Africa may have been advantageous, or convenient, or simply pleasurable—and the tools they made more beautiful, like the 71,000 year-old spear points from Still Bay (left)—ultimately these behaviours were not so crucial for survival that everyone had to make the transition.
Still Bay spear points (Wikipedia).
As world authority on the Middle to Upper Palaeolithic transition Ofer Bar-Yosef from Harvard University explains, the isolated occurrences of African Upper Palaeolithic culture “ultimately had no impact on the general trend of human evolution”. In effect, these sporadic occurrences of Upper Palaeolithic culture did not spread throughout Africa because they were not essential to survival in that region.
So where did the real Upper Palaeolithic revolution begin? Where did the founder group first emerge that was to become today’s global population of humans? The archaeological evidence tells us that our founders came from an area in western Eurasia called the Mediterranean Levant ( see map below ), comprising present-day Israel, Lebanon, Syria, Palestine, the Sinai Peninsula and Jordan. It was these African immigrants, now living in the Levant, who made the transition to an Upper Palaeolithic culture and it was this specific culture that then dispersed across the globe.
Map of the Levant
This seminal transition occurred around 46,000 to 47,000 years ago. It was then that a selection of Upper Palaeolithic behaviours suddenly appeared in a population of Middle Palaeolithic people living at Tachtit Boker, in present-day Israel. Within a few thousand years, this vibrant new Upper Palaeolithic culture had spread to Europe, Africa and Asia.
This places the Mediterranean Levant at the geographical epicenter of humanity—the starting point for humanity’s global colonization of the planet.
The speed of the Upper Palaeolithic revolution in the Levant was also breathtaking. Anthropologists Ofer Bar-Yosef and Bernard Vandermeersch:
Between 40,000 and 45,000 years ago the material culture of western Eurasia changed more than it had during the previous million years. This efflorescence of technological and artistic creativity signifies the emergence of the first culture that observers today would recognize as distinctly human, marked as it was by unceasing invention and variety. During that brief period of 5,000 or so years, the stone tool kit, unchanged in its essential form for ages, suddenly began to differentiate wildly from century to century and from region to region… Why it happened and why it happened when it did constitute two of the greatest outstanding problems in paleoanthropology.
These are not the only outstanding problems. The abrupt metamorphosis of primitive hominids into modern humans that occurred in the Levant is particularly puzzling given that their ancestors in that region and elsewhere had survived for six million years without art, creativity, high intelligence, civilization or most of the other attributes of 21st century humans. If they had survived without language for all that time, why did they suddenly acquire it (as many researchers now believe) only about 50,000 to 100,000 years ago?
Then there are all the peripheral questions. Were Neanderthals and early humans one species? Did they socialize? Did they interbreed? These issues are still being hotly debated, while the big question—why did Neanderthals die out?—generates dozens of theories but no consensus.
This article is an extract from the chapter ‘Mysterious Origins’ in the book ‘ Them and Us: How Neanderthal Predation Created Modern Humans’ by Danny Vendramini and has been published with permission. To read more visit www.themandus.org.