October 31, 2010

Out of Africa

Posted in Language and Myth tagged , , at 11:07 pm by Jeremy

This section of my book, Finding the Li: Towards a Democracy of Consciousness, covers the exodus of modern humans from Africa, and describes what happened when they met the Neanderthals in Europe.  It’s taken from the chapter “The Rise of Mythic Consciousness.”  The section begins by answering the question posed at the end of the previous section, called the “sapient paradox”: if modern humans evolved over 150,000 years, why did it take until 40,000 years ago for human to show symbolic behavior in the Upper Paleolithic revolution?

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Out of Africa

Well actually, according to a growing number of experts, it did happen sooner.  A lot sooner.  In fact, there’s evidence that the beginnings of cultural modernity may have occurred at least seventy-five thousand years ago.  It’s just that it wasn’t in Europe that these stirrings of modernity first showed up, but in South Africa.  In recent years, excavations at two important sites on the coastline of South Africa – Howieson’s Poort and Blombos Cave – have uncovered startling new evidence of symbolic behavior by our human ancestors a full thirty-five thousand years before the Upper Paleolithic revolution in Europe.  Some of the findings include engraved ostrich eggshells and perforated shells that were probably used as personal ornaments, but the most striking treasure unearthed to date has been one particular piece of ochre with a series of complex cross-hatched lines engraved into it.[1] [Figure 3.]  These lines, in the view of archaeologists Renfrew and Mellars “seem certainly to be deliberate patterning”  and represent “the earliest unambiguous forms of abstract ‘art’ so far recorded,” and, along with the other findings, suggest that “the human revolution developed first in Africa … between 150,000 and 70,000 years ago.”[2] In fact, some additional engraved pieces have been found that are even older, leading Mellars to assert that “there is now no question that explicitly symbolic behavior was taking place by 100,000 years ago or earlier.”[3]*

Ochre with cross-hatching from Blombos Cave, South Africa

If our ancestors were thinking symbolically and behaving like modern humans a hundred thousand years ago, then what about the Upper Paleolithic revolution and the Great Leap Forward?  Doesn’t it perhaps begin to seem like a series of tentative steps rather than a great leap?  Certainly some observers think so.  Two archaeologists, Sally McBrearty and Alison Brooks, have caused a stir with an article entitled “The revolution that wasn’t: a new interpretation of the origin of modern human behavior,” arguing exactly this point.[4] And even the momentous findings in Blombos and Howieson’s Poort seem to peter out of the archaeological record after that, suggesting “intermittent” advances in modernity rather than one sweeping tidal wave of progress.[5] Mellars describes the process as possibly “a gradual working out of these new cognitive capacities” of our human ancestors “under the stimulus of various kinds of environmental, demographic, or social pressures.”[6]

But if the excitement of the Great Leap Forward is somewhat diminished, another epic story, perhaps grander than any other, has come into the foreground.  It’s a story that’s emerged through advances in mitochondrial DNA analysis, through which scientists can trace the patterns of previous molecular changes in the DNA of modern humans and thus establish accurate time estimates regarding the migrations of different human groups.  The story can only be called “Out of Africa”  and it goes something like this.  At some time around sixty to eighty thousand years ago, a certain lineage of humans (known as L3 based on their mitochondrial DNA type)  began to expand throughout Africa, becoming the majority population throughout the continent with the exception of the Khoisan (Bushmen) and the Biaka (Pygmies). One group of this L3 lineage got as far north as Ethiopia and from this group a small initial contingent, no more than a few hundred people at most, migrated across the mouth of the Red Sea, through Arabia and eastward along southern Asia until reaching Australia.  This epic journey happened sometime during the period between fifty to sixty-five thousand years ago.   A some point during this migration, another group headed north into western or central Asia, and from there arrived in Europe, where their descendants eventually instigated the Upper Paleolithic “revolution.”  A couple of startling facts arise from this story.  The first is that all non-African people currently alive today are descendants of this very small group of several hundred that made its way across the Red Sea.  Secondly, because of this, there is a far wider genetic diversity between different African populations than between all other non-African people on the planet. [7]

It’s a grand story, but it still raises as many questions as it answers.  What led to the original expansion of the L3 group through Africa?  And how does that tie in with the findings at Blombos Cave?  And we still have the “sapient paradox” to contend with: if humans were acting so modern all this time, why is there nothing special to show for it in the archaeological record other than some pierced shells and cross-hatched ochre until the flowering of achievements in Europe forty thousand years ago?

Archaeologist Richard Klein believes that the answer to the first set of questions may be genetic.  In his view, a genetic mutation, most likely in the “neural capacity for language or for ‘symboling’,” is the best explanation for the dramatic changes that ensued.  Here’s how he argues his case:

When the full sweep of human evolution is considered, it is surely reasonable to propose that the shift to a fully modern behavioral mode and the geographic expansion of modern humans were also coproducts of a selectively advantageous genetic mutation. Arguably, this was the most significant mutation in the human evolutionary series, for it produced an organism that could alter its behavior radically without any change in its anatomy and that could cumulate and transmit the alterations at a speed that anatomical innovation could never match. As a result, the archeological record changed more in a few millennia after 40 ky ago than it had in the prior million years.[8]

There are, however, other explanations for the dramatic transformation in human behavior which don’t require a genetic mutation to happen just at the right time.  Mellars has suggested that a positive feedback loop may have begun with the more efficient hunting weapons that the Blombos and Howieson’s Poort groups would have been capable of constructing.  Increased hunting efficiency, along with expanded trading and exchange networks between different groups, may have led to a sustained growth in population.  In fact, the mitochondrial DNA analysis does suggest rapid population growth between sixty and eighty thousand years ago.[9] Another group of archaeologists has produced mathematical studies showing that once a certain demographic critical size is reached, there is a greater impetus for more innovation and, perhaps most importantly, these innovations are more likely to be copied by other communities, creating a “cultural ratchet effect.”[10]

Either a genetic mutation or the positive feedback loop from denser populations could explain the successful migration out of Africa.  But neither of these are sufficient to explain the Upper Paleolithic revolution.  The population densities in Europe were no greater than those in Africa, and the people who made it to Europe were genetically no different than the rest of the L3 group.  So how might we explain that explosion in symbolic behavior and thus resolve the “sapient paradox”?  An important clue might be found in examining what these L3 humans encountered when they arrived in Europe.

Neanderthals: modern humans met them when they first arrived in Europe

When our human ancestors first showed up in Europe, they weren’t the only ones around.  The continent was already populated by Neanderthals, close cousins of homo sapiens who had diverged genetically only a few hundred thousand years earlier.[11]*  The Neanderthals had withstood more than two hundred thousand years of climatic variations in the cold reaches of Ice Age Europe, and with their heavy-set bodies they would have seemed better equipped than the homo sapiens arriving from Africa to handle Europe’s Ice Age climate.  But within ten thousand years of the arrival of homo sapiens on the scene, the Neanderthals were extinct.

To many anthropologists, the evidence seems cut and dried: the Neanderthals were outcompeted by their cognitively superior cousins.  They were “driven to extinction” by the homo sapiens invaders simply because they were “unable to compete for resources.”  They “perceived and related to the environment around them very differently” than our human ancestors and, as a result, “wielded culture less effectively.”  There’s even been mention of a “Pleistocene holocaust” prompting some observers to look at our more recent historical record and note acerbically that “homo sapiens has not been notable for a tolerance of differences or a drive toward coexistence with differing cultures – to say nothing of competing species.”[12]

Other archaeologists have, however, argued that the situation was not so simple.  In fact, they claim, the Neanderthals showed evidence of symbolic behavior just as sophisticated as that of their homo sapiens competitors.  Traditionally, when bone tools and ornaments were dug up from Neanderthal sites, they were dismissed by arguments that the Neanderthals were just mimicking the homo sapiens invaders without understanding the true meanings of these things.  But recently, the same kind of ornaments have been discovered that date back to fifty thousand years ago, or ten thousand years before modern humans came on the scene, offering unequivocal evidence of Neanderthal symbolic thought.[13] So what should we make of that?

A possible resolution to this debate arises if we go back and consider the three stages of language evolution posited in the previous chapter.[14] Under that hypothesis, the hominids living around three hundred thousand years ago had reached the second stage of language evolution, with a protolanguage that accompanied the stone-working complexity known as Levallois technology (which is associated with the Neanderthals).  Possibly, the Neanderthals had reached that level of cognitive sophistication, but were unable to make the leap across the metaphoric threshold to modern language.  It’s easy to imagine how a group that could say to each other “fire stone hot” would be outcompeted by another group that could say “I put the stone that you gave me in the fire and now it’s hot.”  A recent paper by Coolidge and Wynn speculating on the Neanderthal mind is consistent with this hypothesis, proposing that homo sapiens had greater “syntactical complexity” than the Neanderthals, including the use of subjunctive and future tenses, and that this enhanced use of language may have given modern humans “their ultimate selective advantage over Neandertals.”[15]

However, the competition between homo sapiens and Neanderthals was probably fierce and most likely endured for thousands of years.  In fact, it’s this very competition that might have been the catalyst for the dramatic achievements of the Upper Paleolithic revolution, thus providing a possible solution to the “sapient paradox.”  As we know from modern history, warfare is frequently the grim handmaiden of major technological innovations, and it’s reasonable to believe that the same could have been true of that much earlier conflict.   Conard, for example, has raised the possibility that “processes such as competition at the frontiers between modern and archaic humans contributed to the development of symbolically mediated life as we know it today.”[16]*

There’s more at stake in the possible distinction between Neanderthal and modern human cognition than just a forensic post mortem of how the Neanderthals became extinct.  As we’ll see in the next section, this distinction may help us to understand the underlying sources of the mythic consciousness that became the hallmark of everything accomplished by homo sapiens from that time on.

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[1] Henshilwood, C. S., d’Errico, F., Vanhaeren, M., van Niekert, K., and Jacobs, Z. (2004). “Middle Stone Age Shell Beads from South Africa.” Science, 304, 404; Henshilwood, C. S., and Marean, C. W. (2003). “The Origin of Modern Human Behavior: Critique of the Models and Their Test Implications.” Current Anthropology. City, pp. 627-651; Henshilwood, C. S. et al. (2002). “Emergence of Modern Human Behavior: Middle Stone Age Engravings from South Africa.” Science, 295, 1278-80.

[2] Renfrew, op. cit.; Mellars, P. (2006). “Why did modern human populations disperse from Africa ca. 60,000 years ago?  A new model.” PNAS, 103(June 20, 2006), 9381-9386.

[3] Mellars (2006) op. cit.  Notably, the program director at Blombos, Christopher Henshilwood, sees these findings as evidence that, “at least in southern Africa, Homo sapiens was behaviorally modern about 77,000 years ago,” and other archaeologists who were initially skeptical of these claims are increasingly coming around, acknowledging that “the new material removes any doubt whatsoever.”  See Heshilwood (2002) op. cit., and Balter, M. (2009). “Early Start for Human Art?  Ochre May Revise Timeline.” Science, 323(30 January 2009), 569, quoting archaeologist Paul Pettitt.

[4] McBrearty, S., and Brooks, A. S. (2000). “The revolution that wasn’t: a new interpretation of the origin of modern human behavior.” Journal of Human Evolution, 39(2000), 453-563.

[5] Powell, A., Shennan, S., and Thomas, M. G. (2009). “Late Pleistocene Demography and the Appearance of Modern Human Behavior.” Science, 324(5 June 2009), 1298-1301.

[6] Mellars (2006) op. cit.

[7] Forster, P. (2004). “Ice Ages and the mitochondrial DNA chronology of human dispersals: a review.” Phil. Trans. R. Soc. Lond. B, 359(2004), 255-264; Mellars (2006) op. cit.

[8] Klein, R. G. (2000). “Archeology and the Evolution of Human Behavior.” Evolutionary Anthropology, 9(1), 17-36.

[9] Mellars (2006) op. cit.

[10] Powell, A., Shennan, S., and Thomas, M. G. (2009). “Late Pleistocene Demography and the Appearance of Modern Human Behavior.” Science, 324(5 June 2009), 1298-1301; Culotta, E. (2010). “Did Modern Humans Get Smart Or Just Get Together?” Science, 328, 164.

[11] The Neanderthals and other hominids (for example, homo erectus) had already colonized southern Asia and Europe beginning over a million years ago.  See Mithen, S. (1996). The Prehistory of the Mind, London: Thames & Hudson, 29; Forster, P. (2004) op. cit.

[12] Quotations taken, in order, from the following sources: Forster, P. (2004) op. cit.; Mithen, S. (2006). The Singing Neanderthals: The Origins of Music, Language, Mind, and Body, Cambridge, Mass.: Harvard University Press; Tattersall, I. (2008). “An Evolutionary Framework for the Acquisition of Symbolic Cognition by Homo sapiens.” Comparative Cognition & Behavior Reviews, 3, 99-114; Klein, R. G. (2003). “Whither the Neanderthals?” Science, 299, 1525-1527; Proctor, R. N. (2003). “The Roots of Human Recency: Molecular Anthropology, the Refigured Acheulean, and the UNESCO Response to Auschwitz.” Current Anthropology, 44(2: April 2003), 213-239; Ehrlich, P. R. (2002). Human Natures: Genes, Cultures, and the Human Prospect, New York: Penguin.  See also Mellars, P. (2005). “The Impossible Coincidence. A Single-Species Model for the Origins of Modern Human Behavior in Europe.” Evolutionary Anthropology, 14(1), 12-27 for a valuable discussion on the topic.

[13] Bahn, P. G. (1998). “Neanderthals emancipated.” Nature, 394(20 August 1998), 719-721; Zilhao, J. (2010). “Symbolic use of marine shells and mineral pigments by Iberian Neandertals.” PNAS, 107(3), 1023-1028; d’Errico, F., Zilhao, J., Julien, M., Baffier, D., and Pelegrin, J. (1998). “Neanderthal Acculturation in Western Europe?  A Critical Review of the Evidence and Its Interpretation.” Current Anthropology, 39(Supplement), S1-S43.

[14] See page 41.

[15] Wynn, T., and Coolidge, F. L. (2004). “The expert Neandertal mind.” Journal of Human Evolution, 46(4), 467-487.

[16] Conard (2010) op. cit.  This viewpoint is also argued by David Lewis-Williams who writes: “It was not cooperation but social competition and tension that triggered an ever-widening spiral of social, political and technological change that continued long after the last Neanderthal had died, indeed throughout human history.”  See Lewis-Williams, D. (2002). The Mind In the Cave, London: Thames & Hudson, 96.

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5 Comments »

  1. Richard Choquette said,

    I am fascinated by this topic. Thanks for posting.

    Here are some questions and I acknowledge that answers must be speculative: Can we identify a beginning point for consciousness in prehistory? Was consciousness at some point overlaid upon a substrate of sufficiently advanced cognition? Or does our DNA have a code for what we call consciousness?

    Lately, my speculation has centered around a possible inherant conflict between our DNA natural selection programming and a consciousness that does not hold individual survival as the prime directive.

    I ponder these things because we have no greater mystery to ponder.

    • j-man said,

      Thanks for your feedback, Richard. You might be interested in a post I’ve written called “The bacterium, the fly and the sugar bowl”, which explores the notion of human free will with implications for the development of what we might think of as primary or animate consciousness.

      If you want to get a better sense of the development of our uniquely human form of consciousness – secondary or conceptual consciousness – you could take a look at Chapter 2 of my book, Towards a Democracy of Consciousness, entitled “So What Really Makes Us Human.”

      I hope these help in your search.

  2. Sharon Woods said,

    As a scientist-turned-artist, I’ve studied pictures of European ice age cave paintings. These crosshatches resemble a symbolic method of counting that appears in the form of red or black spots on or above game “kills,” hatches, and perhaps even the abstract basketry patterns. Hatches are also found on very realistically carved miniatures of ice age animals (mammoths and cave lions), with hatch marks or crosses that look like these. These “primitives” were very sophisticated in their art. I think cave paintings doubled both as a beautiful adornment for what I believe were Ice Age homes, and also advertisement to other clan or family members.

  3. […] Out of Africa , post by Jeremy Lent  https://jeremylent.wordpress.com/2010/10/31/out-of-africa/ […]


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