This is Part 6 of a subscriber-only preview of my upcoming book Outsourcing Consciousness: How Social Networks are Making Us Lose Our Minds. We will release the first six chapters through the end of the year. Read Part 1, Part 2, Part 3, Part 4, and Part 5.
O for a Muse of fire, that would ascend
The brightest heaven of invention
Chorus from the Prologue to Henry V by William Shakespeare
One of the most fascinating features of the human obsession with creation stories is our parallel obsession with damning the humans who seek to lay claim to their power. When Prometheus steals the fire of the gods, the source of the knowledge and creativity necessary for civilization, he is chained to a rock, condemned to death by vulture-pecking, and regenerates each morning to withstand the agonies once more. The Golem, Frankenstein’s monster, the Sorcerer’s Apprentice, Tolkien’s flame imperishable, and even modern animated films like Disney’s Moana are all cautionary tales about the consequences of humanity’s hunger for the power of creation and imagination. God’s reaction to Adam and Eve in Genesis 3:22 is the among the earliest such tales: the man has become like one of us. To seek to be like a god is seemingly a near-universal crime.
Pride and the fall are also common themes in literature. Pride leads to excessive risk-taking, so it stands to reason that cultural reinforcement of ‘pride is bad’ stories might propagate across disparate cultures. And there’s not much you can do that shows more pride than to seek to become a god. Institutions and governments with cultural authority have a vested interest in curtailing the ambitions of the people to supplant them, especially if they have claimed a mandate from the gods. So it also stands to reason that ‘ambition beyond your station is bad’ stories might propagate across disparate cultures. Whether there is some more fundamental reason or just ideas that various human cultures have chosen to enforce, we seem to be attracted to the idea that creation and destruction are deeply related. It is appropriate, then, that the first story ever told was about a tool of both creation and destruction. But it isn’t the kind of story we usually think about when we think about a story. It isn’t a myth, a tall tale, a nursery rhyme, or a narration of the day we had at work. But it is a story all the same – a complex symbol built from a temporal or causal sequence of other symbols.
So far, our own story tells how Homo erectus, through a series of evolutionary graduallies and suddenlies, came into possession of a highly encephalized brain and a suite of physiological and social adaptations that went just a bit beyond a janky hip. Homo erectus also possessed fine motor skills, which he employed around 1.8 million years ago in the manufacture of a special kind of tool. Humans and other apes had made use of tools for millions of years at this point, of course. There are even a few impressive examples. For example, chimps have been known to sharpen wooden sticks for hunting[i]. They also throw rocks at trees and stack them in a pile afterward in what appears to be a sort of bizarre mating display, which isn’t all that impressive but does show that males of all species will do weird things to get laid. By and large, however, early tools were either rocks that could be used to smash nuts or other rocks that could be used to smash nuts against.
That had begun to change even before Homo erectus came around. Not the part about trying to get laid, I mean. The part about the tools made by archaic humans. In the last chapter, I briefly mentioned the Oldowan industry, whose artifacts from roughly 2.5 mya were found scattered about the Olduvai Gorge in Tanzania. While this early find gave the industry its name, it did not describe the extent of its spread. Oldowan-style tools have been found in dozens of archaeological sites, from Anhui Province in eastern China[ii] to Occitania in the south of France[iii]. Relative to the sharpened sticks we observe chimps using today – which we may assume might have been well within the capacities of Caliban and his children – Oldowan tools show signs of greater sophistication. They demonstrate stone knapping techniques through which a percussive impact against a certain kind of stone would produce both flakes and a core. Flakes are the bits that come off when you strike the right kind of rock with another one called a hammer stone. The core is what is left after you have struck off one or more flakes. Most of the Oldowan tools we have found are flakes that would have been used as sharp cutting instruments. The modified cores were often used as more robust choppers, too.
Mary Leakey and others involved with some of the first explorations of the Olduvai Gorge site characterized Oldowan as a pebble tool industry[iv]. In broad strokes, that means that the primary material for a variety of tools typically would have been a stone already shaped by nature – often water-based erosion – to look like the tools it would become. Maybe the stone had a protrusion that looked like a flake its maker had seen before, or perhaps it had a holdable, disc-like shape that already seemed to have an edge. As a dad to an 8-year-old, I find it helpful to think about Oldowan and analogous pebble tool industries like you might about your kid playing Harry Potter in the backyard and finding a stick that already kind of looks like a magic wand.
I observed earlier that the bonobo Kanzi struggled to produce tools at an Oldowan level of sophistication. There are a few reasons for this, each of which suggests how Homo habilis and australopithecines potentially involved in the industry may have evolved in the 4-6 million years after Caliban. Kanzi’s greatest difficulty was his struggle to apply the right amount of force at the correct angle while striking the core. This may suggest that the archaic humans responsible for Oldowan tools had developed finer motor skills by this point. Some of those motor skills may have been attributable to the physical structure of the hand. Many more were certainly the result of changes in the brain.
Positron emission tomography (PET) analysis of modern human brains during the replication of Oldowan techniques confirms that these methods activate what we call the parietofrontal network, especially elements which enhance sensorimotor adaptation. Sensorimotor adaptation is how the brain helps you to adjust how hard to strike an object as you learn more about the hardness or brittleness of a material, as you learn more about the striking area of your hammerstone, or as you get used to holding a stone steady as you strike it with another. Much of this network is associated with the posterior parietal lobe. That is an area of the brain for which endocasts of various archaic humans present when the Oldowan industry emerged – including Homo habilis – demonstrate changes in both size and morphology[v]. To put it in much simpler terms, scientists had modern knappers simulate Oldowan techniques and found that doing so activated parts of the brain that would have been enhanced in the hominins of 2.5 mya and not in Caliban or our closest ape cousins.
The evidence is circumstantial, but this is precisely what you would expect given the facts that we have laid out so far. Nature selected obligate bipedalism for Caliban’s children, whether that was in response to changes in social structure and the realities of arboreal child-rearing, a changing ecological niche in the midst of Late Miocene drying, or both. With the adaptation of bipedalism, a changing diet, a rapidly shifting social structure, and other environmental factors, both gestural communication and fine motor skills would have been fruitful areas for natural selection. Some of those adaptations facilitated changes in human physiology, from hand structure, to musculature, to posture. Some of those physiological adaptations, in turn, would have facilitated further adaptations in spinal cord and brain stem structure. All of these would have influenced and been influenced by changes in human social structures and communication. But at various points, both gestural communication and fine motor skills would have reached a natural limit governed by the brains of Caliban’s children.
To be clear, each of the physiological changes mentioned above could not have avoided producing changes in the structure of the brain even in the absence of the selection of any new traits which directly influenced its size or structure. The selection of a modified gene which changed the musculature of the hand, for example, would have caused even the genetically unmodified brain to restructure itself in a variety of ways. Yet it seems likely that the evolutionary advantages of better tools and more thorough voluntary communication would also create direct selection pressure for a mind capable of exploiting them. What we know from endocasts of late australopithecines and limited Homo habilis skulls is that changes not only in the internal structure of the brain but in its size and morphology had taken place – general encephalization and expansion of the posterior lobe chief among them. What PET analysis tells us is that this very brain structure and its role in governing sensorimotor adaptation would be associated with the execution of the Oldowan industry. What we can infer is that the selection of genetic modifications which would result in modest general encephalization and the specific expansion of the posterior parietal lobe almost certainly took place between Caliban (8 mya) and Homo habilis (2.5 mya). What we might also infer is that both these and various musculoskeletal adaptations would have produced internal changes to the neuronal structure and connectedness of the brain which played a role in facilitating this industry.
Yet it is what the PET imaging did not show that might be more important to our story. And what it did not show was meaningful activation of key areas of the brain’s working memory network during execution of Oldowan techniques[vi]. That includes both the pre-frontal cortex (PFC) as well as the ventral precentral gyrus (vPrG). As I alluded to briefly, the PFC might be thought of as the control center of the brain. Beyond its central role in the working memory network, it is the structure which is most responsible for suppressing our immediate instinct to be concrete and deterministic in our thinking. It is the brain structure most involved with keeping our mind open to possibilities, to various ways things might relate to other things rather than fixating on what things seem to be causally related to (indexical relationships) or represent in themselves (iconic relationships). The vPrG also plays a role in working memory but is more narrowly focused on visual working memory associated with sensorimotor functions. Imagine a physical process which requires planning a sequence of movements, coordinating multiple body parts, integrating sensory feedback, and maintaining a motor plan. An amateur golfer suffers through mid-swing thoughts of correcting a nasty slice habit, or else a slightly intoxicated millennial tries desperately to recreate what they remember of the Macarena.
The manufacture of Oldowan tools is too simple to require activation of such brain structures, some of which were probably underdeveloped in early hominins of 2.5 mya anyway. Instead, it basically required the ability to flake tools off a core that typically started out in a rough version of its final shape. To exaggerate somewhat the claims of Putt et al for dramatic effect, it was a process much closer to the stick sharpening of chimps than the later toolmaking of neolithic hominins like Homo erectus[vii]. It required some fine motor control and the capacity and respond and adjust to visual stimuli, but not much else. Given the spread of its techniques across several continents over a period of a million years, it almost certainly benefitted from social structures and other cognitive adaptations which would allow it to be taught and learned and passed on to others, if only through mimicry. But it didn’t necessarily require this. Neither did it require a mind that could plan or imagine, at least not to degrees that vastly exceeded the capacities of other apes. Nor did it require the capacity to suppress the instinct to dismiss a potential core as inappropriate because it did not match the target shape of the tool.
In theory, the worldwide spread of Oldowan industry could simply suggest that hominin fine motor skills had permitted the independent discovery by individuals in far-flung locales of how useful it might be to look for stones that already look like a tool. In semiotic terms, we could call this an iconic sign relation, of a kind that would not require social reinforcement. The spread of the industry might also reflect mimicry of a cause-and-effect relationship between a simple striking motion and a sharp flake popping off. We would call this an indexical relation, dependent on some context or experience for understanding the underlying casual relationship but similarly independent of social or cultural reinforcement. In practice, however, archaeological evidence still suggests that early hominin social structures and rudimentary forms of proto-communication almost certainly accelerated the spread of this technology. But however widespread, the product of improved fine motor skills and social structures which had evolved somewhat since Orrorin took his hesitant first steps in Late Miocene Africa is not the telling of a story.
What happened a little less than a million years later and about 600 miles north of the Olduvai Gorge is another matter. Here, about 1.8 million years ago, humanity told its first story. Or if you are so pedantic as to deny me that poetic license, this is the age of the oldest artifacts which indicate very strongly that what I will argue constitutes story was being produced by archaic humans. It is the story of the axe that never was.
The Acheulean Industry
What paleoanthropologists call the Acheulean industry – named for where we first discovered it near Saint-Acheul in northern France – is another method for the creation of stone tools. In many ways, Acheulean tools are very much like Oldowan tools. To you and me they might not be indistinguishable, but neither would they seem to represent the great leap I am attributing to them. Both industries leverage percussive lithic reduction techniques to produce stone tools that cut things, chop things, and bang on things. Yet as modest as the visual change in the product of these industries might be, the changes in the hominin brain required to manufacture them were more significant.
Unlike the Oldowan industry, the Acheulean industry was not a pebble tool industry. Relying forever on the good fortune to locate stones that already looked like the end tool would have been a hindrance to productivity and whatever adaptive benefits the tools might have in the first place. With this new technology, archaic humanity escaped this requirement. Acheulean tools were the products of planning and selection of stones based on other qualities, conducted with the understanding that cores could be shaped and flaked into appropriate and useful end shapes at a later stage in production. In certain cases, for example, we can observe that practitioners were even in the habit of creating blanks. Those are partially pre-shaped stones which could be conformed later to a variety of different shapes and tool purposes that any group of archaic humans required.
In expanding the set of possible materials from which to fashion tools, Acheulean industry consequently required the systematization of core preparation. The hallmark of the Acheulean industry was the production of large cutting tools, most notably the distinctive hand axe. These tools were characterized by their bilateral symmetry and bifacial construction, features that required a level of planning and execution far beyond what was necessary for Oldowan tools. The toolmaker had to carefully remove flakes from both sides of the core, maintaining a symmetrical edge around the entire perimeter. This process often involved hundreds of precisely aimed strikes, in which each removal influenced subsequent flaking decisions. Those decisions might be driven by the desired tool use, how the stone chosen responded to different sorts of pressure, the nature of the tool being used to shape and flake it, or tradeoffs between strength, sharpness, and symmetry. The result was a tool with a regularized form, typically almond-shaped or ovate, with a sharp cutting edge around its circumference. To achieve this, the production of these tools also required an understanding of the properties of different stone materials. Toolmakers showed a clear preference for fine-grained rocks like flint or quartzite, which allowed for greater control in shaping and produced sharper edges. In many cases, these materials were transported over long distances, indicating foresight and planning in resource acquisition.
While Oldowan tools varied widely in shape and size, Acheulean hand axes often adhered to specific forms that were replicated across vast distances and time periods. This standardization suggests not only a shared mental template among toolmakers but also the ability to teach and learn complex sequences of actions. More importantly, it suggests the capacity to communicate and internalize the meaning or purpose of those actions, since they often would not have been self-evident in isolation.
The sophistication of Acheulean industry is demonstrated further by the development of more specialized tools alongside the ubiquitous hand axe. These included cleavers, picks, and various forms of scrapers, each designed for specific tasks. The ability to create a diverse toolkit, with each implement requiring its own production sequence, speaks to a level of cognitive flexibility, creativity, and complex social organization not seen in earlier industries. Perhaps most telling is the emergence of ‘final shaping' techniques in later Acheulean assemblages. These involved the careful removal of small flakes to refine the tool's edge and overall shape, a process that required not only exceptional motor control but also a clear vision of the desired end product. This ability to hold an abstract mental image – a symbol – of the finished tool and work towards it through multiple stages of reduction is a clear indicator of advanced cognitive capabilities, bridging the gap between the concrete world of physical objects and the abstract realm of concepts and plans.
So why is the axe that never was humanity’s first story? Because we know that a human mind somehow successfully conveyed symbolic thought – that of an axehead in an end state which did not resemble its starting state or many of its interim states – as part of a causal sequence that would lead to its construction. Because we know that simple mimicry without the understanding of the meaning of that symbol, without the capacity to suppress the iconic and indexical impulses to associate actions with an end state they indicated, could not have produced the Acheulean industry. The Acheulean axehead required the imagination and communication of a symbolic causal sequence.
But in the same way that it would be wrong to say that it is the size of the human brain alone which distinguishes us as a species, it would be wrong to conclude that simple advances in raw cognition were what distinguished Homo erectus and the Acheulean industry. The advancements in tool production techniques in the Acheulean industry correlate strongly with certain of the specific neurobiological changes we may observe in Homo erectus. In a variety of neuroimaging studies and techniques, the precision required for bifacial knapping, the maintenance of symmetry, and the planning involved in creating standardized forms point to increased activation of the frontal lobe rather than the predominant activation of the posterior parietal lobe typical of Oldowan tool manufacture. Disproportionate widening of the frontal lobe beyond what general encephalization of hominin brains would predict is a feature of archaic human evolution beginning in earnest with Homo erectus[viii]. Exactly which structures of the frontal lobe are involved in Acheulean manufacture, however, is a matter of more recent debate. It is also one of some interest to us.
In a pair of studies led by the now-director of the Center for Mind, Brain & Culture at Emory University, Dr. Dietrich Stout, a team of paleoanthropologists identified significant activation of the prefrontal cortex during modern replication of the manufacture of Acheulean tools[ix]. This region of the brain, as previously mentioned, is crucial for executive functions such as planning, along with working memory and inhibitory control. It is not difficult to imagine how this would aid the Acheulean manufacturing process. The ability to suppress immediate responses in favor of long-term goals – to resist, for instance, the urge to strike at an obvious protrusion in favor of maintaining the overall symmetry of the tool – is a logical case study for the engagement of the prefrontal cortex. Acheulean toolmaking often involved a multi-stage process where the final shape emerged gradually. This might require the toolmaker to inhibit the urge to remove too much material too quickly. He needed to anticipate future stages of the tool's development and preserve adequate core material for these later steps. This might well involve suppressing the desire for immediate progress in favor of a more measured, long-term approach.
The creation of advanced Acheulean tools also involved alternating between rough shaping and fine detailing. This might require the toolmaker to inhibit the motor patterns associated with forceful, large-flake removal when switching to the delicate work of edge refinement. The ability to rapidly switch between these two modes of working, suppressing the motor habits of one to engage in the other, demonstrates cognitive flexibility and motor inhibition that are characteristic of prefrontal cortex function. It also engages similar lateralization to what we'd observe with another complex cognitive task – the production of language. This level of controlled, context-dependent behavior shift is not evident in the simpler, more repetitive techniques of the Oldowan industry.
And yet a subsequent study – the 2017 paper submitted to Nature by a group led by Stone Age Institute postdoctoral fellow Dr. Shelby Putt mentioned earlier this chapter – found something a bit different. They reproduced Stout’s analysis with a couple important modifications. First, they used a different neuroimaging technology called functional near-infrared spectroscopy, which may produce fewer artefacts than PET or comparable imaging methods. More importantly, they attempted to isolate whether the study participants who engaged in Oldowan or Acheulean manufacturing tasks learned or imitated the method in response to a verbal language-based description or a non-verbal demonstration. It turned out that the simulation only reproduced the unusual prefrontal cortex activity for those who learned the Acheulean method by hearing it. Those who learned by watching principally engaged a source of visual working memory through the ventral precentral gyrus (vPcG), a fold in the brain containing a functional area known as the ventral premotor cortex (vPMC). Since few scholars believe anything approaching structured language existed as far back as 1.8 mya, the results allow us to infer a more indirect relationship between the neurological capacities underlying toolmaking and language than what Stout’s earlier work implied to many scholars. Still, both the PFC and vPMC are frontal lobe features and implicated, if not positively indicated, by the peculiar expansion of frontal lobe width in Homo erectus.
For reasons I will explore in greater detail, it is likely that the rapid and disproportionate growth and connectivity of the PFC and related distributed networks played a significant role in the development of human symbolic thought, language, storytelling, and cognition more broadly. As a result, the stories Stout and Putt tell about how and when we acquired our mantle of storyteller and storyseeker are similarly instructive. They are also somewhat different. In short, we might have inferred from Stout that the expansion of the prefrontal cortex in Homo erectus was a prerequisite for more advanced toolmaking, a process which would have redoubled various selection pressures on the continued expansion and connectivity of the PFC to various brain functions. From Putt, we may instead infer that PFC expansion was perhaps selected as the result of something slightly different – the rising working memory and coordination demands of communicating and thinking in multiple different modes. Either way, what sent Caliban into exile from Eden would also transform Homo erectus into the first storyteller on our planet: managing multi-modality.
Managing Multi-Modality
I have argued that the axe that never was constitutes humanity’s first story. But how did Homo erectus tell it? We know that Acheulean tools were surprisingly consistent across time and distance, implying some measure of precision to how other archaic humans acquired the knowledge of their construction. Given that artifacts from Acheulean industry can be found in India, Kenya, Tanzania, and England, too, we know that the spread of the tool required a mind in some that could carry that story. Perhaps even to conduct a rudimentary form of trade with other groups of the same and co-existing species of Homo. We know that Homo erectus had a big brain. We know that it had developed certain neural structures that would later become necessary for producing and interpreting structured language. But surely such language did not exist 1.8 million years ago, at least beyond what some researchers have called a pragmatic grammar of short symbolic sequences. If it did, we would be left to wonder why it did not produce clearer signs of rapid growth in sociocultural complexity like the ones we can observe from 60,000 – 130,000 years ago[x]
There are other possibilities. In 1992, a group of Italian cognitive neuroscientists led by University of Parma scholars Giuseppi di Pellegrino, Luciano Fadiga, Vittorio Gallese and Giacomo Rizzolatti published a seminal paper in the Experimental Brain Research journal that provided an intriguing such possibility. What the Parmigiani discovered was a class of neuron in a major premotor control region of the brain of the Macaque monkey – the ventral premotor cortex we just met from Putt’s Acheulean industry replication study. Those neurons demonstrated a special property. Unsurprisingly for this part of the brain, they discharged when the monkey executed a particular motor action, like grasping, tearing, or holding an object. Rather more surprisingly, they also discharged when the monkey observed one of the human researchers performing those actions. Neuroimaging also showed that the areas with neuron activity were often highly specific to the action being executed and witnessed. The region of a monkey’s brain activated by a motor action, like gripping an object, were often the same whether the monkey was doing it or just observing it. Those regions were often different from those activated by a different motor action, like tearing or holding[xi]
Groundbreaking as the mirror neuron might have been, the initial response to the discovery was tepid. Lead scientist Rizzolatti later recalled his initial submission of the paper to Nature, perhaps the most widely read and prestigious scientific journal. They rejected it, he said, because of its ‘lack of general interest.[xii]‘ This response mirrored, if you will, the initial response to earlier research from this same group showing similar neuron activity when a monkey performed a motor action and when it saw an object that would be associated with that motor action. The ‘gripping’ region of premotor areas of the brain lit up on the simple appearance of a ‘grippable’ object. In retrospect, it is surprising that the response was so limited. The mirror neuron indicated a potential explanation for the unique capacity of Homo sapiens not just to mimic but to learn through such acts of mimcry – a mimetic impulse, to borrow a phrase from the Greeks.
Despite the lethargic initial reaction, over the ensuing years researchers continued to find new evidence of sympathetic neuron response in the acts of observing and executing varieties of actions. Most importantly, those findings began to include direct evidence of these responses in humans themselves and not just Macaque monkeys. There were two complications, however. The first is that expanded neuroimaging of humans showed mirror neuron response well outside premotor and motor control areas of the brain. If neurons were firing in so many places, was the response in the premotor and motor regions of the brain special or just a coincidence? Was it just part of a broader brain response to sensory inputs? The second complication was that there was far less evidence that non-human apes engaged in similar learning through imitation, at least in the way that humans did it[xiii]. If neurons fired upon observing an action by an ape who did not really learn by imitation, could it really explain mimetic learning and communication in humans?
Over time, researchers began to resolve these complications. Yes, the human mimetic brain is different[xiv]. And far from being a problem for the mirror neuron theory, the broad neural response outside of premotor and motor control regions of the brain ended up being part of the theory’s best proofs. Around 2010, one study from a team of Australian neuroscientists explored an area of the brain called the superior temporal sulcus, or STS. If you think of the brain as having hills and valleys, the STS is a long, shallow valley that runs along the side of your brain, almost from the front to the back, just above your ears. It separates two hills in a part of the brain called the temporal lobe. A lot of special things happen in this valley. When you passively watch another human perform a physical action, neurons in the STS fire. When you perform a similar action, neurons in the STS fire. When you perform the action upon hearing a verbal command to do so, neurons in the STS fire. But when you perform the action in imitation of another, neurons in the STS go wild[xv]. Our brains evolved to imitate, to teach through demonstration, and to learn through imitation. The mirror neuron system, as we now understand the much more complex and multi-faceted human version of this adaptation, is a key feature of that evolution, and the STS is one among many brain structures that appear to be part of it.
The implications of the discovery of mirror neurons were significant. Even before deeper research into the Acheulean industry, scientists from a variety of fields had long known that pre-language humans must have been capable of forms of symbolic thought – of suppressing the instinct to assume iconic or indexical relationships between two things. They knew that because they had found archaeological evidence that humans were doing things which required social behaviors, planning, or organization, or else abstract, symbolic thinking at various points in pre-history. Many archaeological finds suggest the presence of both. For example, systems of food storage or long-distance voyages tell us about planning, group coordination, and the development and teaching of technologies. Ornamentation and other evidence of rituals tell us about both abstract and communicative social practices.
There is a great deal of such evidence beyond what is implicit in toolmaking methods like the Acheulean industry we have spent so much time discussing. For example, in southern Africa we have discovered ‘eminently symbolic’ art that stretches beyond the boundaries of when structured oral language was thought to exist, from 100,000 years ago or more[xvi]. Geometric engravings by Homo erectus are visible on a shell found in Indonesia from at least 400,000 years ago[xvii]. In Northern Germany, we surmised from the remains of slaughtered animals that even our cousins the Neanderthals had the capacity to set up elaborate hunting strategies and meat processing operations[xviii]. There is evidence of pigmentation use in modern South Africa from at least 300,000 years ago that seems indicative of coalition signaling[xix]. All these achievements would have required abstract thought and the transformation of that abstract thought into forms digestible, recognizable, and learnable by other humans. You can imagine, I hope, the importance of the discovery of the mirror neuron to this mimetic theory of learning and communication. It offered more than a circumstantial argument from the archaeological record or a compelling causal argument based on the general truths of evolutionary biology. It identified a physiological mechanism whereby demonstration, observation, and imitation facilitated the exchange of complex, abstract, and symbolic ideas from one brain to another without a word of structured language.
On this basis alone, we might argue that Acheulean industry might even have been a story told by and through mirror neurons – that we came to understand the purpose and meaning of steps in the manufacture of more sophisticated tools, that we could envision a template in our mind consistent with that of another by using our brain’s ability to inhibit the concrete cognition demanded of us by Oldowan and other more primitive stone toolmaking industries. And yet we cannot limit the origins of human storytelling only to the strictly mimetic. As noted previously, Homo erectus fossils show evidence of movement on the path to speech. We may infer from the shape and position of the hyoid bone and increased flexion in the cranial base, for example, that he would have possessed a lowered larynx that was on the path to more human-like morphology and position. This would have increased the size of the pharyngeal cavity and allowed for a greater range of vowel sounds than earlier hominins. Homo erectus also boasted an enlarged thoracic vertebral canal, suggesting it might have exercised enhanced control over respiratory muscles. This would also have been crucial for sustained vocalization. While certainly not as developed as in modern humans, these adaptations collectively suggest that Homo erectus had significantly enhanced vocal capabilities compared to its predecessors, potentially enabling more complex forms of vocal communication.
Beyond advances in vocalization capacities, Homo erectus also exhibited several adaptations that would have affected its ability to process the sounds of vocalized communication, especially compared to australopithecines and Homo habilis. For example, analysis of fossilized cochleae from Homo erectus specimens reveals structural changes that might have made it more sensitive to frequencies typical of human speech, with structures more closely resembling those of modern humans[xx]. Its middle ear anatomy, particularly the configuration of the ossicles, appears more human-like than that of earlier hominins. This may have allowed for better transmission of speech-relevant frequencies[xxi]. The structure of the temporal bone shows modifications consistent with enhanced auditory capabilities, especially within the frequency range of human speech[xxii].
None of these changes in auditory processing or vocal apparatuses would have made Homo erectus anything like the vocal communicator that Homo sapiens is, but it is important these many traits were selected in the first place. The more frequently stereotyped calls of other apes and early hominins probably would not have benefitted greatly from such adaptations. Considering both sets of adaptations in tandem, it is improbable that these changes would not have been connected to an increase in the conscious and intentional use of speech, even if it were not part of anything approaching what we might call language.
Neither should we fail to consider the extent to which the sophistication of gestural communication may well have been a beneficiary of the very same neurobiological and musculoskeletal adaptations which so benefitted other fine motor skills. Beyond the general encephalization that took place, Homo erectus endocasts show significantly expanded asymmetry in Broca’s cap, a structure which plays an important role in both verbal and gestural language[xxiii]. The density of neural circuitry necessary for the pooling and sharing of information among brain structures so critical to all communication had expanded, too[xxiv]. Even as early as Australopithecus afarensis there was evidence of reorganization of the posterior parietal cortex that probably permitted enhanced visuospatial and sensorimotor integration critical to more advanced gesturing[xxv]. While only indicated in Homo erectus by endocast impressions of the larger structures which it connects in the brain of modern humans, it would not be unreasonable to speculate some growth in the arcuate fasciculus, too. That is a neural pathway that is critical to the integration of gesture and speech[xxvi].
The story from Caliban to our storytelling selves is, once again, a story of co-evolution and multi-modality. It is a story of the increasing need for the adaptation of brain structures like the modern human’s prefrontal cortex and precuneus to coordinate multiple modalities of thinking and communicating. We could certainly suppose that a single sequence of events led from bipedal hominins to anatomically modern humans, but this is rarely how the story of evolution goes. The plasticity of the human brain and the network-forming tendencies of all but the most modular structures of those brains all lend themselves to a narrative in which multiple physiological, neurobiological, and cultural features of archaic man underwent a period of evolving together, mutually reinforcing the growth of new neural networks and the selection of further adaptations that might make the most of them.
For our purposes, anyway, whether Stout or Putt have the right of it doesn’t really matter. Under Stout we assume that the rise of the prefrontal cortex which transformed us into what Deacon called the ‘symbolic species’ was already very much underway by the time Homo erectus got around to telling the story of the axe that never was. Under Putt we may infer (or at least strongly suspect) that growth in the ventral precentral gyrus and other motor and working memory-oriented structures became part of a set of adaptations which kicked off a selection process that led to a restructuring of the brain around the growth, executive function, working memory, and inhibitory functions of the prefrontal cortex and an associated working memory network at some point thereafter.
Since there is no consequence to the story we are telling in choosing between the two, I don’t mind saying that Putt’s contention seems the more likely. I say that in part because the imaging data presented makes a compelling case that the PFC may not have played as core a role in advanced toolmaking from 1.8 million years ago, even though evidence of the physical restructuring of the prefrontal cortex was already evident in australopithecines from two million years earlier. Putt showed that Acheulean industry activated both visual and auditory working memory centers but not otherwise distinct verbal centers. Her hypothesis is that the ventral premotor cortex may well have been an ‘integration area’ that served as a ‘starting point for the evolution of verbal [working memory],[xxvii]’aided by its indispensable role in the human mirror neuron system. I think that Putt’s case accordingly supports a more comprehensive narrative in which the co-evolution of auditory, gestural, mirror neuron, cognitive, and at some point probably verbal functions created the demand for evolution’s selection of a more central coordinating function – just the job for the prefrontal cortex. More complex decision-making places more demands on it[xxviii]. Switching between mental sets, like might take place when communicating or learning through multiple modalities simultaneously, requires it[xxix]. The coordination of multiple cognitive operations – like receiving reinforced training in a new skill while performing and mimicking the motor actions and imagining various end results of those actions – would very likely lean heavily on the prefrontal cortex and other functional areas responsible for executive function, too[xxx].
Rather than conclude that man told his first story through mirror neurons, vocalizations, gestures, an inner voice, or some other means altogether, the story of Homo erectus’s various communication adaptations and the consistent spread of the Acheulean industry imply that all of them probably played a role. I think humanity’s first story was told by gesture, by mimetic imitation, and perhaps at some stage during the period of dominance of the Acheulean industry, by the earliest examples of protolanguage. Whether or not that protolanguage could have been present at the earliest stages of Acheulean production, whether it evolved gradually over the next 1.7 million years, or whether it exploded rapidly from protolanguage to fully structured language over the last 150,000 years is a matter of ongoing debate among paleoanthropologists. It is deeply fascinating and worth knowing.
But it doesn’t particularly matter to our topic.
The story of the outsourcing of consciousness depends only on this: that humanity was symbolic before it was oral, and that the way it became oral almost certainly rapidly adapted to that symbolic nature to be more easily acquired and spread. It is this latter consideration which must occupy our attention as we follow Caliban’s children after they stole fire from Hephaestus. After God declared that the man had become like us. For it is not only the co-evolution of our brain, bodies, and societies to become multi-modal communicators but also the evolution of symbolic systems like storytelling that made us so susceptible to the alien lifeform we call the social network.
There is nothing more important to the understanding of 'what social networks are doing to us' than the way our brains acquire symbolic systems and the way that symbolic systems adapt to become more easily acquired by our brains.
Continue with Chapter 6.
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