The Astonishing Prefrontal Cortex: Part One - Four Astonishments

By ChatGPT.

This series of essays is based on what I call “four astonishments” as stated here.  Notice I don't say "the" four astonishments.  There is much that is astonishing about our world and being alive.  Here's four things, by no means all.  Don't worry if they don't make sense yet.  They will.

First Astonishment: The brain's prefrontal cortex's pre-adaptive development created cognitive potential for emergent properties that weren't demanded by evolution.

Second Astonishment: The synchronous development of the PFC with Broca's and Wernicke's areas created conditions for emergent cognitive capabilities through their unique integration.

Third Astonishment: Human history represents the gradual discovery of emergent capabilities within our neural architecture, primarily driven by the PFC's integration with other brain regions.

Fourth Astonishment: We're likely still in the early stages of discovering emergent cognitive capabilities, particularly because advances in neuroscscience, psychology and technology create new possibilities for neural integration.

Here's why these things are astonishing and what they mean.

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Dawn breaks over the African savanna. A female hominin freezes mid-stride, her fingers tightening around a half-eaten fruit. A rustle in the tall grass triggers an instant cascade of physical responses - quickened breath, tensed muscles, heightened awareness. She can see over the tall grass because her ancestors learned to walk on just two feet millions of years ago. This enabled her to stand and run as opposed to try to race along using the knuckles of her hands. Being upright gave her a greater sense of spatial awareness as it created binocular vision for the first time in our species.

In her newly manifested peripheral mind, images flash: the shadow-shape of a big cat, the gleam of teeth, the arc of a deadly pounce. Without conscious thought, her body prepares for either flight or defense. This is imagination in its most primitive form - the ability to simulate threat from subtle cues, an ancient survival mechanism shaped by countless encounters between predator and prey. Her hands grasp a flaked piece of stone, one of the first of its kind.

As the afternoon heat shimmers across the same grassland, a male hominin crouches at the edge of a woodland. The tribe's camp is behind him. His eyes track the movement of distant antelope, but his mind sees more than just their current position. In his mental imagery, he sees their likely path toward the hidden waterhole beyond the acacia trees. He visualizes where they will emerge from the tree line, how they will move across the open ground. This ability to project visual patterns into unseen spaces marks a new kind of imagination - one that extends sight beyond the immediate and visible

These two persons, both skilled at gathering and scavenging, will mate and have several children according to nebulous customs (passed down through the observation of limited, repetitive expressions, gestures and crude sounds) of their tribe. Most of their children will die for various reasons including the act of birth itself, which sometimes killed the mother too. The children's parents will likely die before they are 40 for various reasons like disease, starvation, predators, natural disasters, fighting, and stupidity (one of our oldest traits still around today). A few of the children carry on, grow to observe what others can teach them, and try very hard to remember it. They will mate and have children and then likely die before they are 40.  It is 3.3 million years ago.

Now it is one million years ago as a male hominin crouches at the edge of a woodland. His eyes track the movement of distant prey, but his mind sees more than just their current position. In his mental imagery, he sees their likely path toward the hidden waterhole beyond the acacia trees. He visualizes where they will emerge from the tree line, how they will move across the open ground. This ability to project visual patterns into unseen spaces marks a new kind of imagination - one that extends sight beyond the immediate and visible.  Lightning strikes with an instaneous clap of thunder.  He will go find the resulting fire, if there is one.

Under a blistering sun a half million years later, an elderly female (she is 50), born of the same ancient lineage, leads a small band across seemingly featureless terrain. Her highly developed hippocampus, evolved from the same neural foundations that have saved countless persons from predators, now weaves together decades of memories into detailed mental maps. In her mind's eye, she walks through a landscape rich with remembered landmarks - the lightning-struck tree, the mossy rock formation, the patch of sweet berries. This capacity for spatial memory would be passed down through her children, enabling future generations to navigate ever-larger territories.

A young male toolmaker, carrying his distant great-great-grandmother's genetic legacy, holds a stone core in his calloused hands. His fingers move across its surface with inherited precision. Before he strikes it, his mind has already traced the path of the perfect blow, felt the shock of impact, seen the flake that will peel away. This integration of touch, sight, and movement - a neural gift refined through countless generations - enables him to see finished tools within raw stone. His children will carry this capacity for transformative imagination forward, eventually leading to descendants who would shape not just stone, but metal and silicon.  It is 300,000 years ago.

Under a sky bright with unfamiliar star patterns, a young woman stands at the edge of her tribe's camp. Her brain, though she cannot know it, represents something unprecedented in the history of life on Earth. Behind her high forehead lies a neural architecture capable of abstract thought and complex language that she or anyone else she knows will barely use. Her mind, like her ancestors', still primarily processes immediate threats and opportunities. She watches the night shadows with the same ancient vigilance, but occasionally something different stirs in her awareness - fleeting sensations of thoughts beyond the concrete and immediate.

She belongs to a tribe of accomplished hunters and gatherers, their survival dependent on both tracking prey and intimately knowing every edible plant in their territory. When she teaches her daughter to weave grasses into carrying bags, her hands sometimes pause as if reaching for concepts she cannot quite grasp. Around the campfire, she sometimes finds herself consumed by questions that none of her ancestors could have conceived. Why do lights in the darkness overhead move in patterns? What lies beyond the mountains? She contemplates a dream. She will live and die never knowing that her skull houses cognitive potential far beyond what she'll ever use. Yet her descendants and their children will carry this same neural architecture forward through the generations, until eventually, slowly, humanity will begin to discover its latent capabilities, one abstract thought at a time.

A female shaman stands under the trees, her mind racing with possibilities. In her neural architecture, every cognitive gift - fear response, visual prediction, spatial memory, tool imagination, social understanding, and self-awareness – remain alert as she gathers fruits and leaves for rituals and medicine. These rituals are something new, something none of her ancestors possessed – the ability to construct complex future scenarios, to coordinate group actions through shared symbolic planning. She imagines not just the hunt, but how to teach future generations to hunt better, how to cut up and disseminate a kill, how to ensure the tribe's survival through changing seasons.

This simple story ends about 70,000 years ago just as a handful of our tribes began to migrate out of Africa.  It reveals something remarkable: the cognitive leaps made out of our brains were built upon neural architecture that was already in place, waiting to be used in new ways. This pattern - of brain structure preceding function - reached its most profound expression with the maturing development of the human prefrontal cortex.

The cognitive road map of this fictional lineage - from basic fear responses to complex strategic planning to focused intentions and imagination - represents the broader story of human consciousness. But this story contains a profound mystery. While we can trace the gradual development of brain regions and their capabilities across evolutionary time, the prefrontal cortex seems to break this pattern.

Unlike the amygdala's clear role in survival responses, or the hippocampus's advantage in spatial memory, the prefrontal cortex (PFC) emerged fully formed anatomically long before humans discovered its potential for complex planning and abstract thought. It was as if nature had built a supercomputer in our heads hundreds of thousands of years before we wrote the software to run it.  That is pre-adaptive evolution. So what was it used for during all that time?  It was underused mostly as an emotional regulator, far below its capacity.

This pre-adaptive development of the PFC - its existence long before its ultimate purpose was discovered or experienced by anybody at all - forces us to upgrade everything we thought we knew about human cognitive evolution. The evidence suggests that our capacity for creation and organization and abstract thought wasn't directly selected for by evolutionary pressures or by natural human behavior. Instead, it emerged as an inevitable capability, enabled by the coordination of brain structures that evolved for entirely different reasons.

Astonishingly, a fundamental insight emerging from current research is that the human PFC developed its current anatomical form long before humans actually used it for complex language or abstract thinking. We have literally been in the same brain for 200,000 years.  It was ready to go.  But we didn't know anything and didn't have much to say.  There were very few words and countless languages likely died out through the vastness of the human centuries.  

This pre-adaptive evolution appears to have been driven by anatomical changes related to bipedalism and forward-facing vision, rather than by cognitive demands.  Other explanations might be better but, whatever the reason, there were no cognitive demands pushing us to the limit as there are today.  It was truly an unintended consequence of things.  Nothing was needing all that neural space grow.  Truly form preceded function in this case.

According to a discussion on Quora by neurotheorist John Light in 2020: “When vertebrates first appeared, they were low to the ground, and the front part of the brain was primarily the olfactory bulb. The rest of the brain was behind that, with the spinal cord coming out the back. A thin cortex covered the midbrain. The front of the cortex (frontal cortex) was the motor cortex and somatosensory cortex, followed by the auditory and visual cortex. So the cortex was basically for sensory and motor modalities added onto the midbrain. Initially, brain expansion involved thickening the cortex.

“When still four-legged animals started lifting their heads off the ground, the front of the head tilted down relative to the spine, and this opened up more space in the cortex behind the frontal cortex. This allowed expansion of midbrain functions like memory into the cortex.

“Primates went even further, and their eyes remained looking forward in front of a vertical spine, opening up much more space for cortex growth, which was used for much larger visual processing areas and somewhat larger memory and hearing areas.

“The primate change also resulted in the eyes being positioned lower in the head to minimized optic nerve distance to the thalamus. This opened up space above the eyes for expansion of the cortex. Rather than move the motor cortex forward, which might have necessitated complex brain architecture changes, primates grew additional cortex in front of the motor cortex and found new uses for it.

“The new cortex in the front of the brain is called the pre-frontal cortex. Behind it is the motor cortex, which is really the only other part of the frontal cortex. The functions assigned to this new cortex seem to be new functionality rather than expansion of old functionality. The prefrontal cortex in primates grew as primates became exceptional in many ways, but it really took off in size as pre-humans became noticeably human.

“The prefrontal cortex seems to be the central site of language processing and understanding, and it also seems to be the site of judgment and human intelligence, though many other brain areas contribute to both.”  (Like Mithen's theory in Part Two, bipedalism might not have worked exactly like this, but the PFC's abrupt growth was triggered by something anatomically of this nature.)

A big chunk of those “other brain areas” involve the Broca's and Wernike's areas, which I will turn to soon enough.  The important thing for now is to note that, according to Light: “The prefrontal cortex in primates grew as primates became exceptional in many ways...”  Light is saying that, for example, we had opposable thumbs which allowed us to do all kinds of things with our hands that other animals could not.  That was exceptional in a general sense but we are also talking about “exceptional” individuals pioneering human cognition, particularly in our long years of slow, early cognitive acquisition.  This is an astonishing fact to which I will return.  

This pre-adaptive development created what might be called "unused neural real estate" that largely sat dormant or underused for over 150,000 years. The PFC reached its present anatomical form long before we find any evidence of widespread abstract thinking around 50,000 years ago.  The PFC was just sitting there, mostly idling, although it likely played a part in our migrations out of Africa which began around this same time, which is fascinating to consider!

This vast gap between having the neural hardware and discovering its potential raises profound questions about human consciousness and potential. Just as all descendants gradually discovered new ways to use their evolving brains, from basic threat detection to complex social cognition, our species has been haphazardly discovering things by using (without being aware of it, naturally) the PFC.

The first humans to tap into this latent cognitive potential were likely exceptional individuals - early “geniuses” who pioneered new ways of thinking and created frameworks that helped others access these capabilities.  They did this largely without actual intention, simply because they were geniuses and had absolutely nothing else to do with their exceptional cognitive minds in a world without much knowledge at all.  So they shared it with others who mostly had no clue what he or she was doing. 

This is why nothing changed for many thousands of millennia for our ancestors.  We were all really dumb except for how to survive and communicate with one another.  Of course, these are hopeful characteristics within us still, to be so old.  Language and survival skills kept the species alive (and do so even today) and allowed it, gradually through neurodivergence (genetic mutation) and geniuses, to evolve.  Consider how the toolmaker in our lineage discovered new ways to imagine future forms in stone, or how the elderly leader learned to construct complex mental maps. Each cognitive advance required someone to first discover these possibilities within their pre-existing neural architecture.

Something astonishing happened to the human brain hundreds of thousands of years ago.  The part of the brain that controls decision-making, reasoning, intentions, and much of our social behavior, the PFC, rapidly in evolutionary terms, blasted outward into the forehead of the skulls of our ancestors.  There was no great demand for this.  It was not the result of inherent environmental or psychological tension.  The PFC did not adapt to anything particularly.  It simply emerged over the course of many millennia.

Human beings did virtually nothing with this region of the brain for almost 185,000 years!  We have exactly the same brain structure today!  This is what I call the first astonishment.  For the most part, it just sat there.  We used it for social, emotional, or instinctual behavior but, though sophisticated, that did not tax its abilities.  "Dark cloud there means rain coming" (direct environmental pattern recognition). "That noise means danger" (immediate threat response). "Red berries here means food" (simple association). "Baby crying means give milk" (instinctual response).  This was the extent of human "thinking" at that time.  

These weren't "thoughts" as we understand them today - there was no internal monologue, no sense of "I" or "me," no abstract categorization. They were immediate associations between environmental inputs and behavioral outputs.

The PFC's primary role during this long period was regulating these basic responses, maintaining group cohesion through instinctual reactions to social signals, and coordinating simple survival behaviors. Even these vital functions utilized just a fraction of its capacity. The sophisticated self-awareness we take for granted - our ability to think about thinking, to imagine abstract scenarios, to construct complex causal chains - hadn't yet emerged. Consciousness was more immediate, focused entirely on direct experience rather than abstract contemplation. 

This vast gap between these simple pattern recognitions and our modern capacity for abstract thought demonstrates just how much of our cognitive potential remained untapped during this extended period.  Higher level demand for the PFC was limited to a random idea in special people that usually died out and emotional regulation to keep us from killing each other (though sometimes we did anyway, just as we do today).  

Almost no one was capable of comprehending complex planning and abstract cognition.  Furthermore, in absence of certain higher-level beliefs and practices that have only been around the past few thousand years, emotional control was (and still is to a large degree) more instinctual, sub-conscious.  Wise persons regulated their emotions very well, this is called emotional intelligence today.  It likely predates abstract thought by an immense amount of time. Such regulatory capability does not test the PFC's potential. Across the expanse of millennia the hardwiring of our brains to the PFC was initially minimal.

During that expanse of time, higher demand on the PFC was strictly the purview of neurodivergent people and geniuses who typically did not live very long.  These exceptional people passed along their “knowledge” by seeking to be observed by others who likely were uncomprehending of what they witnessed and could immitate.  Little if anything was learned, most everything was soon discarded, forgotten, or lost due to disease or predatory attacks or starvation or simple mindless neglect.  The PFC was there but no one used it to its full potential.  Extraordinary!

Perhaps even more extraordinary, however, is neuroscience has revealed that the PFC is not a single, uniform region but rather a sophisticated system of at least four, maybe five, specialized sub-regions, each handling different aspects of cognition and behavior. These include areas dedicated to executive function, emotional processing, social cognition, and complex decision-making.  Despite this diversity of these specialized regions, however, all of them reached their present anatomical form simultaneously around 200,000 years ago.

Without getting too bogged down here, one region is dedicated to working memory, planning, and cognitive flexibility while another specializes in cognitive control processes like task-switching and inhibition.  Another is involved in self-referential thinking, social cognition and emotional processing relevant to these. A fourth is involved in reward evaluation, decision-making and emotional processing of these behaviors.  There is also a region that is actually part of the brain's limbic system, but it works so closely with the PFC that it is often included in discussions of prefrontal function. It's involved in error detection, conflict monitoring, and the resulting emotional regulation pertaining to those functions.

Notice most of these sub-regions contain a strong element of emotional regulation in specific brain functions.  Clearly, as I have mentioned, the PFC was of great utility in this capacity long before the development of complex organizational and abstract thought.  It is reasonable to assume that the PFC was mostly an emotional regulator before more complex cognition evolved.  I will return to the importance of this fact later this series.

The precise evolutionary sequence of these sub-regions appears to have developed in synchronized fashion. Nature didn't just create empty neural space - it built an intricate, multi-faceted system with specialized components, all of which emerged before humans had any significant use for them. It's comparable to finding not just a basic computer, but a sophisticated multi-processor system, in the hands of someone who hasn't yet discovered electricity.

This complexity makes the pre-adaptive development even more astonishing. The PFC arrived with all its specialized machinery intact: regions for managing working memory and planning, areas for processing emotions and rewards, systems for social understanding and self-reflection. Yet for many thousands of generations, these sophisticated neural tools remained largely unused, waiting for humanity to discover their potential through the gradual development of complex language and abstract thought.  

This anatomical sophistication also helps explain the extraordinary range of cognitive capabilities that eventually emerged. When humans finally began accessing this neural architecture, they found not just raw processing power, but specialized systems capable of supporting everything from mathematical reasoning to artistic expression, from philosophical contemplation to scientific analysis. Importantly, we are still discovering new ways to utilize this remarkable neural inheritance today.

Which brings us to a second mystery about the brain is perhaps even more remarkable. As the PFC developed through millions of years, two other fundamental brain regions - Broca's and Wernicke's areas - were evolving separately toward their contemporary form. These emergent language-processing centers were driven by human learning itself, by our capacity to speak and to understand and behave accordingly.  Though these three brain regions all began to evolve at countless years apart, all three incredibly arrived at their present state inside our skulls at roughly the same time.  

This is the second astonishment.  These three brain regions reaching maturity, in concert with the instinctual and emotional aspects of the brain, created a cognitive architecture perfectly suited for abstract thought and complex communication, yet one that wouldn't be fully utilized for millennia.

This synchronous development suggests something profound about human cognitive evolution. While the PFC provided the potential space for abstract thinking and complex understanding, Broca's and Wernicke's areas provided the tools to manipulate, communicate  and understand abstract concepts. The first humans to bridge these capabilities - to use social language for non-social purposes (see Part Two) - were likely the earliest geniuses of our species. These cognitive pioneers discovered how to use their neural architecture in novel ways, creating the first abstract frameworks that others could follow.  By definition, they were neurodivergent.

Through countless generations, these exceptional individuals - shamans, toolmakers, healers, hunters and early leaders - pushed the boundaries of what was possible with their language. They created the first metaphors, the first abstract categories, the first complex narratives about unseen forces and future possibilities. Their insights, though often imperfectly understood by their contemporaries and often completely forgotten, gradually carved neural pathways that others could follow, slowly teaching humanity how to access the latent potential that had been waiting in their brains for thousands of generations.

This co-evolution of language and abstract thought created a powerful feedback loop. As language became more sophisticated, it enabled more complex abstract thinking. As abstract thinking developed, it required and inspired more nuanced forms of language. Each advance made new forms of thought and expression possible, gradually unlocking more of the potential that had been built into our neural architecture.

The evidence for this process can be seen in the archaeological record. Around 70,000-50,000 years ago, something remarkable started to happen inside the PFC.  Suddenly, the capabilities which had been there underused all along began to blossom. We begin to see the first clear signs of symbolic thinking: cave art, ritual burial, decorative objects, and more sophisticated tools. We migrated out of Africa.  This "explosion" wasn't the result of any new biological evolution.  Our brains are anatomically exactly the same as theirs.  Rather, it represented humanity finally beginning to discover how to use its pre-existing cognitive capabilities.

The PFC continues to shape human development today. The same prefrontal cortex that our ancestors used to create the first abstract categories now allows us to manipulate quantum equations. The same language areas that first enabled metaphorical thinking now let us program computers and compose symphonies.  Before the agricultural revolution about 12,000 years ago, the vast majority of people used their PFC haphazardly.  Masterful usage was only possible in select individuals.  Yet, everything that has happened since the growth of mass farming, big cities, collective religions, and a multitude of inventions has used the PFC to exist in our awareness.  This is the third astonishment.  The PFC is the inner structure of human history.

Other regions of the brain are clearly involved, of course, but without the PFC those other regions have completely different effects on behavior.  Studies conducted on PFC damage and impairment, exemplified by the famous case of Phineas Gage, provides incontrovertible insights into both the function of this brain region and its role in human cognitive evolution. After surviving an iron rod through his frontal lobe, Gage's personality and behavior changed dramatically while other cognitive functions remained intact. This pattern - specific loss of executive function and social cognition while basic abilities remain - characterizes PFC damage.

Individuals with PFC impairment show marked difficulties with planning, organization, impulse control, and abstract thinking. They struggle to regulate emotions, display inappropriate social behavior, and have reduced capacity for introspection.  This is who we used to be prior to migrating out of Africa.  Their memory, basic language skills, and motor functions typically remain normal. This suggests that the PFC provides a sophisticated layer of cognitive processing atop more fundamental brain functions.

The pattern of deficits seen in PFC damage - particularly the loss of abstract thinking while concrete abilities remain - offers a window into what human cognition might have been like before the full utilization of PFC capabilities. It suggests that accessing PFC capabilities isn't automatic but requires proper development of neural pathways, aligning with the theory that early humans had to gradually discover how to use these cognitive abilities, initially led by exceptional individuals who could first access them.

Finally, a fourth astonishment is realizing that there's no reason to think we've reached the limits of what our neural systems can do.  We mistakenly believe that because our cognition is the way it is now is the only way we are supposed to be.  Looking at my fictional lineage, no one really would have had such a thought but it is nevertheless true of each of them.  To be any other way would be strange.  Indeed, the very fact that our most sophisticated cognitive capabilities emerged from brain structures that evolved for other purposes suggests something remarkable: we may still be in the early stages of discovering our potential. There  are likely other latent capabilities or awarenesses waiting to be discovered in our remarkably pre-adapted brains.

Just as children today learn primarily through observation and imitation before developing the capacity for abstract thought in adolescence, our species, over vast stretches of time, followed a remarkably similar pattern. For hundreds of thousands of years, human learning was primarily imitative and observational. Only relatively recently, in evolutionary terms, did we begin to develop widespread abstract thinking and systematic mastering our environment.

This parallel between individual and species-wide cognitive development is an underappreciated fact. Just as adolescents all over the world, across all cultures are still learning to fully utilize their cognitive potential, humanity itself appears to be in a similar phase of development - as a species, we are measurably growing into our PFC. This developmental parallel provides further evidence that we're still in the early stages of our cognitive evolution, more akin to adolescents exploring new capabilities than mature adults who have reached their full potential.

This is the story we will explore - how an extraordinary happenstance of evolution created cognitive potential far beyond immediate survival needs, how early geniuses began to discover and develop these capabilities especially through language, and what this suggests about humanity's continuing cognitive evolution. It is a story that challenges our understanding of both our past and our future, suggesting that human consciousness itself might be better understood not as the end product of biological evolution, but as an ongoing discovery of capabilities that have been waiting all along inside our brains.

(to be continued)