Jeff Hawkins, On Intelligence (2004)

The scenario described in the previous post (see October 26, 2013 post) of the mass of commuter humanity changing trains in a crowded subway station, silently cooperating to avoid colliding with one another as they cross paths was intended to introduce the subject of humans reading and understanding the intentions of others as a foundation of human cooperative activity.  But there is another characteristic of the human brain besides mindreading that supports this outcome:  the human brain constantly anticipates, predicts the future.  In this scenario, it predicts (perhaps not perfectly) the future behavior of others (more likely their immediate behavior), where they are directing their motion, where they are turning, whether they are accelerating or slowing down.  Jeff Hawkins labels this intelligence:  how the brain predicts behavior and future events is the subject of On Intelligence. Hawkins' interest is in understanding human intelligence to build a foundation for improved machine intelligence. The focus of his inquiry is the neocortex, the outermost layers of the human brain, and memory.  What Hawkins offers up is the memory-prediction framework of intelligence.  This differs from a computational framework.

Hawkins is not out to explain what makes us human (compare September 27, 2009 post).  Nor is he out to explain human consciousness (compare April 8, 2011 post).  But he does briefly touch on these matters.  Previous posts in the blog address human imagination and creativity as a hallmark of what makes us "human,"  (see November 6, 2011 and May 22, 2011 post), and Hawkins presents a model discussed below about the role of the neocortex in imagination, including imagination by false analogy.  What he does not touch on is the role of the brain in generating and controlling emotions, the subject of Jaak Panksepp's research (see May 19, 2013 post), which naturally links to the origins of the moral and social aspects of what makes us human.  (See November 21, 2012 post).  So while Hawkins does connect the neocortex and thalamus within his memory-prediction framework (see below), he does not elaborate upon the role of the large thalamo-cortical system that resides in the human brain that plays a substantial role in what makes us human and the biological basis of human consciousness.  (See April 8, 2011 post).

Prior posts identify the critical role of the hippocampus in memory formation, but ultimately long-term memory is shifted to the cerebral cortex through a process known as consolidation that occurs during sleep.   (See September 10, 2013 and November 6, 2011 posts).  As a prior post described:  "Memories are distributed in the same parts of the brain that encoded the original experience. So sounds are found in the auditory cortex, taste and skin sensory memories are found in the somatosensory cortex, and sight in the visual cortex. But procedural -- "how to" --- memories are stored outside of the cortex, in the cerebellum and putamen, and fear memories are stored in the amygdala."  Hawkins' thesis is that the cortex is critical to human capacity to predict events because of the linkage to memory storage in the cortex.  In focusing on the neocortex, Hawkins is looking at, evolutionarily speaking, the most recent adaptation in the development of animal neurological systems.  The neocortex is unique to mammals, and the human neocortex is larger than the neocortex in any other mammal, facts that suggest the human neocortex is critical to understanding what makes us human. This is just the opposite of Jaak Panksepp's focus on the older parts of the brain, the brain stem and the midbrain.  (See May 19, 2013 post).  It is not as though Hawkins believes these older parts of the brain are irrelevant to human behavior.  "First," Hawkins says, "the human mind is created not only by the neocortex but also by the emotional systems of the old brain and by the complexity of the human body.  To be human you need all of your biological machinery, not just a cortex."  But Hawkins is ultimately interested in the creation of an intelligent machine, and he believes that in the pursuit of that interest he needs to understand what makes humans "intelligent."  He finds that understanding in how the neocortex is structured and proposes a model for how it operates to predict future events. 

Hawkins' model is based on our current knowledge of the structure of the neocortex.  That much is known.  And here is a graphical representation of that structure:



                                                           SENSORY INPUT

Each region of the neocortex is known to consist of four areas, labeled 1, 2, 4 and IT. The graph above represents those four layers, with IT at the top and 4, 2, and 1 below it for one of the regions of the cortex (visual, auditory, somatosensory, motor). The visual cortex layers are labeled, from bottom to top, V1, V2, V4, and IT; the auditory cortex layers labeled A1, A2, A4 and IT; the somatosensory (touch) cortex layers labeled S1, S2, S4 and IT, and similarly for the motor cortex.  The arrows are pointed in both directions, indicating that information moves in both directions between the areas. 

Neurons fire in a specific pattern in response to a specific sensory stimulus.  For the exact same sensory stimulus, the same neurons will fire in the same pattern within this hierarchy.  For a different sensory stimulus, different neurons will fire in a pattern.  The brain's capacity to recognize (predict) these patterns is at the heart of memory.

Recall the discussion in connection with Rodrigo Quiroges' book, Borges and Memory (September 10, 2013 post):  "Each neuron in the retina responds to a particular point, and we can infer the outline of a cube starting from the activity of about thirty of them [retinal neurons].  Next the neurons in the primary visual cortex fire in response to oriented lines; fewer neurons are involved and yet the cube is more clearly seen.  This information is received in turn by neurons in higher visual areas, which are triggered by more complex patterns --- for example, the angles defined by the crossing of two or three lines.  . . As the processing of visual information progresses through different brain areas, the information represented by each neuron becomes more complex, and at the same time fewer neurons are needed to encode a given stimulus."  The arrows representing sensory input from the retinal neurons are the arrows pointing to area V1 of the visual cortex.  A particular pattern of neurons firing in V1 leads neurons in V2 to fire, and all the way up to IT.  As just noted, in each higher layer "fewer neurons are involved."  In V1, the cells are spatially specific, tiny feature-recognition cells that infrequently fire depending on which of the millions of retinal neurons are providing sensory input; at the higher IT, the cells are constantly firing, spatially non-specific, object recognition cells.  One of way of thinking about this is that certain neurons in V1 fired in recognition of two ears, a nose, two eyes, and perhaps even more details like the texture of skin, facial hair, the color of hair; neurons in IT fired in recognition of an entire head or face.  Cells in the IT encode for categories; Hawkins calls them "invariant representations."  In philosophy, these invariant representations might be analogous to Plato's forms.  It is here one would find neurons firing in response to things --- rocks, platypuses, your house, a song, Jennifer Aniston or Bill Clinton.  (See September 10, 2013 post). 

Psychologists recognize the same phenomenon, although in different terms.  Paul Bloom asserts that humans are "splitters" and "lumpers," but for the most part we are lumpers. Borges' Funes was a splitter.  (See September 10, 2013 post).    "Our minds have evolved," Bloom says, "to put things into categories and to ignore or downplay what makes these things distinct.  Some categories are more obvious than others: all children understand the categories chairs and tigers; only scientists are comfortable with the categories such as ungulates and quarks.  What all categories share is that they capture a potential infinity of individuals under a single perspective.  They lump."  Bloom says, "We lump the world into categories so that we can learn."  He adds, "A perfect memory, one that treats each experience as a distinct thing-in-itself, is useless.  The whole point of storing the past is to make sense of the present and to plan for the future.  Without categories [or concepts], everything is perfectly different from everything else, and nothing can be generalized or learned."     

The neocortex consists of six horizontal layers of cells (I-VI) each roughly 2mm thick (shown below for area V1 of the visual cortex).   The cells within each layer are aligned in columns perpendicular to the layers.  The layers in each column are connected via axons, making synapses along the way.  "Columns do not stand out like neat little pillars," explains Hawkins, "nothing in the cortex is that simple, but their existence can be inferred from several lines of evidence."  Vertically aligned cells tend to become active for the same stimulus. 

 

Again, as was the case with the different areas of a region of the cortex, information is moving both up and down the layers of a given area.  Inputs move up the columns; memories move down the columns.  "When you begin to realize that the cortex's core function is to make predictions, then you have to put feedback into the model; the brain has to send information flowing back toward the region that first receives inputs.  Prediction requires a comparison between what is happening and what you expect to happen.  What is actually happening flows up, and what you expect to happen flows down."
 
Memories are stored in this hierarchical structure.  "The design of the cortex and the method by which it learns naturally discover the hierarchical relationships in the world.  You are not born with knowledge of language, houses, or music.  The cortex has a clever learning algorithm that naturally finds whatever hierarchical structure exists and captures it.  When structure is absent, we are thrown into confusion, even chaos. *** You can only experience a subset of the world at any moment in time.  You can only be in one room of your home, looking in one direction.  Because of the hierarchy of the cortex, you are able to know that you are at home, in your living room, looking at a window, even though at that moment your eyes happened to be fixated on a window latch.  Higher regions of cortex are maintaining a representation of your home, while lower regions are representing rooms, and still lower regions are looking at window.  Similarly, the hierarchy allows you to know you are listening to both a song and album of music, even though at any point in time you are hearing only one note, which on its own tells you next to nothing."  Critical to this capability is the brain's ability to process sequences and recognize patterns of sequences.  "Information flowing in to the brain naturally arrives as a sequence of patterns."  When the patterns are repeated through a repeated firing of a particular combination of neurons, the cortical region forms a persistent representation, or memory, for the sequence.  In learning sequences, we form invariant representations of objects.  When certain input patterns repeat over and over, cortical regions "know that those experiences are caused by a real object in the world." 

One of the most important attributes of Hawkins' model is a concept called auto-associative memory.  This is what enables the brain to recall something by sensing only a portion of that memory.  In the case of the brain, that input may belong to an entirely different category than what is recalled.  Auto-associative memory is part of pattern recognition:  the cortex does not need to see the entire pattern in order to recognize the larger pattern.  The second feature of auto-associative memory, says Hawkins, is that an auto-associative memory can be designed to store sequences of patterns, or temporal patterns.  He says this is accomplished by adding a time-delay to feedback. 

The cortex is linked to the thalamus.  Hawkins says that one of the six layers of cells (L5 - second from the bottom in a given cortical area) within the neocortex is wired to the thalamus, which in turn sends information back to Layer I (the highest layer in a given cortical layer), acting as a delayed feedback important to learning sequences and to predicting.  The thalamus is selective in what it transmits back to the cortex because the number of neurons going to the thalamus exceeds the number of neurons back to the cortex by a factor of ten.  This requires an understanding of reentrant activity and recursion, which need not be explained here.  But Layer 1 (at the top of a given cortical area) is also receiving information from higher cortical areas (e.g. in the case of the visual cortex, layer 1 in V4 from layer 6 in IT; layer 1 in V2 from layer 6 in V4, etc.)  So layer 1 now has two inputs:  from the thalamus and from the higher cortical area.  Layer 1, Hawkins emphasizes, now carries "much of the information we need to predict when a column should be active.  Using these two signals in layer 1, a region of cortex can learn and recall multiple sequences of patterns." 

Cortical regions "store" sequences of patterns when synapses are strengthened by repeated firing.  "If this occurs often enough, the layer 1 synapses [at the top of the region] become strong enough to make the cells in layers 2, 3, and 5 [below] fire, even when a layer 4 cell hasn't fired--- meaning parts of the column can become active without receiving input from a lower region of the cortex.  In this way, cells in layers 2, 3, and 5 learn to 'anticipate' when they should fire based on the pattern in layer 1.  Before learning, the column can only come active if driven by a layer 4 cell.  After learning, the column can become partially active via memory.  When a column becomes active via layer1 synapses, it is anticipating being driven from below.  This is prediction.  If the column could speak, it would say, 'When I have been active in the past, this particular set of my layer 1 synapses have been active.  So when I see this particular set again, I will fire in anticipation.'  Finally, layer 6 cells can send their output back into layer 4 cells of their own column.  Hawkins says that when they do, our predictions become the input.  This is what we do, he adds, when we daydream, think, imagine.  It allows us to see the consequences of our own predictions, noting that we do this when we plan the future, rehearse speeches, and worry about future events.  In Hawkins' model, this has to be part of what Michael Gazzaniga refers to as our decoupling mechanism.  (See May 22, 2011 post)

This is Hawkins' model of the brain's capacity to predict, intelligence if you will.  Of course, it is a  more complex than I have regurgitated here.  "If a region of cortex finds it can reliably and predictably move among these input patterns using a series of physical motions (such as saccades of the eyes or fondling with the fingers) and can predict them accurately as they unfold in time (such as the sounds comprising a song or the spoken word), the brain interprets these as having a causal relationship.  The odds of numerous input patters occurring in the same relation over and over again by sheer coincidence are vanishingly small.  A predictable sequence of patterns must be part of a larger object that really exists.  So reliable predictability is an ironclad way of knowing that different events in the world are physically tied together.  Every face has eyes, ears, mouth and nose.  If the brain sees an eye, the saccades and sees another eye, then saccades and sees a mouth, it can feel certain it is seeing a face."

This begins at a very early age in our post-natal development.  The two basic components of learning, explains Hawkins, are forming the classifications of patterns and building sequences.  "The basics of forming sequences is to group patterns together that are part of the same object.  One way to do this is by grouping patterns that occur contiguously in time.  If a child holds a toy in her hand and slowly moves it, her brain can safely assume that the image on her retina is of the same object moment to moment, and therefore the changing set of patterns can be grouped together.  At other times, you need outside instruction to help you decide which patterns belong together.  To learn that apples and bananas are fruits, but carrots and celery are not, requires a teacher to guide you to group these items as fruits.  Either way, your brain slowly builds sequences of patterns that belong together.  But as a region of cortex builds sequences, the input to the next region changes.  The input changes from representing mostly individual patterns to representing groups of patterns.  The input to a region changes from notes to melodies, from letters to words, from noses to faces, and so on.  Where before a region built sequences of letters, it now builds sequences of words,  The unexpected result of this learning process is that, during repetitive learning, representations of objects move down the cortical hierarchy.  During the early years of your life, your memories of the world first form in higher regions of cortex, but as you learn they are re-formed in lower and lower parts of the cortical hierarchy."

Michael Shermer (see June 12, 2011 post) made the same point in a slightly different way when he referred to "patternicity."  According to Shermer, as sensory data flows into the brain, there is a "tendency" for the brain to begin looking for meaningful patterns in both meaningful and meaningless data. He calls this process patternicity. Shermer asserts that patternicity is premised on "association learning," which is "fundamental to all animal behavior from which is "fundamental to all animal behavior from C. elegans (roundworm) to homo sapiens." Because our survival may depend on split-second decisions in which there is no time to research and discover underlying facts about every threat or opportunity that faces us, evolution set the brain's default mode in the position of assuming that all patterns are real, says Shermer. A cost associated with this behavior is that the brain may lump causal associations (e.g. wind causes plants to rustle) with non-causal associations (e.g. there is an unseen agent in the plants). In this circumstance, superstition --- incorrect causal associations --- is born. "In this sense, patternicities such as superstition and magical thinking are not so much errors in cognition as they are the natural processes of a learning brain." Religion, conspiracy theories and political beliefs fit this model as well.

My surmise is that beliefs and concepts rooted in false analogy become stored in memory in higher cortical areas when they are reinforced over and over through cultural transmission.  Something like this may be what Edward O. Wilson means when he refers to epigenetic rules and culture. "Human nature," Wilson says, is the "inherited regularities of mental development common to our species. They are epigenetic rules, which evolved by the interaction of genetic and cultural evolution that occurred over a long period in deep prehistory. These rules are the genetic biases in the way our senses perceive the world, the symbolic coding by which we represent the world, the options we automatically open to ourselves, and the responses we find easiest and most rewarding to make. . ."  (See April 8, 2013 post).  Storytelling --- the creation of works of fiction --- may be important to making and reinforcing memories.  (See August 15, 2011 post).  Thus, when a prediction based on a false analogy is violated and one would normally recognize an error, the error message is transmitted back up to the higher cortical areas for a check.  But because the belief based in false analogy resides there in the higher areas, the false analogy may never be corrected. The false analogy becomes an invariant representation.  Paul Bloom explains in Descartes' Baby just how these concepts and beliefs can be rooted in our brains at a very early age, and as Hawkins describes above, memories formed earlier in life form in the higher regions of the cortex.  These false analogies can be difficult to dislodge.

Hawkins has been helpful in providing a model of the cortex as the part of the brain devoted to our capacity to predict.  When tied into the models of other parts of the brain relating to consciousness and emotion discussed elsewhere in this blog, we begin to assemble the whole human brain and begin an appreciation of what makes us "human."  (See September 27, 2009 post discussing Michael Gazzaniga's reference to Jeff Hawkins).  While Hawkins' interest lies in the intelligent machine, he does not believe a machine can ever become "human."

And finally, Hawkins confirms why I have had held to my instinct that John Searle's Chinese Room argument was intuitively correct.  The man in the Chinese Room must have been human.

Jaak Panksepp and Lucy Biven, The Archaeology of Mind, Neuroevolutionary Origins of Human Emotions (2012)

At its most fundamental level, the neurosensory system of every animal, including humans, is a physiological system related to monitoring our entire physical system, whether the animal is awake or not, and, when awake (including the sleep-wake transition period), reacting to stimuli.  The latter is referred to as the arousal system.  In the case of vertebrates, four neurotransmitters (chemicals) --- acetylcholine, norepinephrine, dopamine, and serotonin --- stimulate different arousal systems originating in the brain stem, evolutionarily the oldest part of the vertebrate brain, and motivate certain behaviors such as seeking food, flight or fight behavior, and sexual activity.  There are certain emotional systems that are virtually at the core of the arousal system, at least during periods of wakefulness, and for several decades now, Jaak Panksepp has been researching and advocating that these emotional systems have their origins with animals evolutionarily older than humans, located in the older subcortical areas of mammalian brains and only later connected with the cortical areas. 

The Archaeology of Mind begins and ends with vertebrate animals, yet the evolutionary story is older, and to tell the story of what is missing from Panksepp's account I excerpt heavily from Steven Rose's The Future of the Brain, which outlines the evolution of the brain from unicellular organisms, to eukaryotes, to invertebrate animals and vertebrates.  This excerpting is important to a point I wish to make.  Rose says this:

"By the time that cells capable of metabolism and faithful replication, of symbiogenesis and competition appear, all the defining features of life have emerged:  the presence of a semi-permeable boundary separating self from non-self; the ability to metabolise -- that is, to extract energy from the environment so as to maintain this self --- and to self-repair, at least to a degree when damaged; and to reproduce copies of this self more or less faithfully.  All of these features require something we may term adaptability or behavior --- the capacity to respond to and act upon the environment in such a way as to enhance survival and replication.  At its simplest, this behavior requires neither brains nor  nervous systems, albeit a sophisticated set of chemical and structural features.  What it does require is the property that some would call a program:  at its most general way of describing both the individual chemical components of the cell and the kinetics of their interactions as the cell or living system persists through time. ***

"Built into this program must also be the possibility of modifying its expression, transiently or lastingly, in response to the changing contingencies of the external environment.  *** One way of conceiving of this capacity to vary a program is as an action plan, an 'internal representation' of the desired goal-- at its minimum, that of survival at least until replication is achieved.  I will be arguing that, in multicellular organisms, such action plans are ultimately what brains are about.

"Amongst the most basic forms of adaptive behavior drawing on such action plans is goal-directed movement-- of a unicell swimming towards food for instance. [Emphasis added].  Dip a thin capillary tube containing a solution of glucose into a drop of bacteria-rich liquid, and the bacteria collect around the mouth of the capillary from which the glucose diffuses--a phenomenon first noted as long ago as the nineteenth century.  Such simple responses engage a series of necessary steps.  First, the cell needs to be able to sense the food.  In the simplest case the food is a source of desirable chemicals --- perhaps sugars or amino acids-- although it may also be the metabolic waste products excreted by another organism.  Indeed the molecule does not have to be edible itself provided it can indicate the presence of other molecules that can be metabolized-- that is, it acts as a signal.  *** But signals are only signals if there is recipient who can interpret the message they bear.  Cell membranes are studded with proteins whose structure is adapted to enable them to trap and bind specific signaling molecules floating past them, and hence read their message.  This chemical detection system is the most basic of all sensory mechanisms.

"Interpreting the message --- using it to develop a plan of action -- should make it possible for the cell to determine the direction of the gradient and finally to move up it to the source.  Moving towards a specific chemical source --- chemotaxis --- requires that the cell possess some sort of direction indicator or compass.  One way of creating such a compass, employed by bacteria, is to swim in a jerky trajectory, enabling the cell to interpret the gradient by comparing the concentration of the attractant chemical at any moment with that a moment before.***"

If Jaak Panksepp were reading this passage he would certainly connect it to his research of emotions in animal brains.  It describes the precursor to what Panksepp regards as the most central emotional system in mammals: the SEEKING system (see below).  Rose continues:

"The molecules trapped by the receptor on the surface membrane serve as signals, but very weak ones.  To produce as dramatic a cellular response as turning and moving in the right direction requires that signals are highly amplified.  The mechanism by which this is carried out, even in the seemingly simplest of unicells turns out to be the basis on which the entire complex apparatus of nervous systems and brains is subsequently built.  The receptors are large proteins, oriented across the lipid membrane, with regions sticking out into the external environment, and also 'tails' which reach into the interior of the cell (the cytoplasm).  When the signal receptor binds to the receptor protein its effect is to force a change -- a twist, if you like -- in the complex shape of the receptor.  ***

"One way of speaking of this process, favoured by neurologist Antonio Damasio, even in so limited an animal as Paramecium, is as 'expressing an emotion.'   Emotion for Damasio, is a fundamental aspect of existing and a major driver of evolution.

"*** With multicellularity, 'behaviour' becomes a property of the organism as a whole, to which 'needs' of individual cells are subordinated.  The internal representation which makes possible the action plan for organism can be delegated to specific cell ensembles.  This requires new modes of communication to be developed.  Where previously there were only two classes of signals -- those arriving from the external environment to the cell surface, and those internal to the cell --- there are now three.  Signals from the external environment are still registered by sensory cells on the surface and are transmuted by molecular cascades with them, but now the response to those cascades requires that further messages be sent from the sensory cells to other regions of the body, including of course the contractile cells.  Sometimes the sensory cells make contact with intermediaries whose task it is to synthesise and secrete the necessary 'messenger molecules.'  [Emphasis added]. The messengers can then be distributed through the body either by way of a circulatory system or by diffusion through the extracellular space between the body cells, and are detected as before by specialized receptor proteins on the surface membranes of their targets.  When molecules that served such messenger functions were first identified in mammals, they were given the generic name of hormones.  It was only later, and to some surprise, that it was discovered that many of the same molecules also serve as intercellular signals in very early multicellular organisms, another powerful example of evolutionary conservation.***

"It is easy to imagine a sequence whereby neurons evolved from secretory cells.  Instead of discharging their contents generally into the surrounding space and circulatory system, the secretory cells could have put out feelers (called 'processes') enabling them to make direct contact with their targets so as to signal rapidly to them and them alone.  Messages could be conveyed between the two either electrically or chemically --- by a depolarizing wave or by secreting a messenger molecule across the membrane at the point where the two cells touch.  In fact, both phenomena are know to occur.

"The first step towards such nervous systems can be seen among the large group of Coelenterates, believed to be amongst the earliest true multicellular animals.  The best known is perhaps the Hydra, a tiny creature that sits at the bottom of streams attached to rocks or water plants, waving its tentacles above its mouth.   When a potential source of food brushes past its tentacles, the Hydra shoots out poisonous threads, collects the paralysed victim and thrusts it into its mouth.  *** A well fed Hydra is quiescent; when hungry it waves its tentacles vigorously, or moves its location by repeatedly turning head-over-heals, seeking food-rich or oxygen-rich environments (once again, Damasio would regard these acts 'expressing emotions').***

"What distinguishes a fully-fledged nervous system --- our own for instance --- is a one-way flow of information through the system, from dendrites to axon, from sensory cell to effector.  Of course this is mediated via all the feedback loops, but none the less there is a directionality to it that the Hydra's does not possess.

"Whereas the Hydra's neurons are scattered throughout the body, the next crucial step was to concentrate them within an organized system. *** C. elegans  has a head and tail end, and as it is more important for it to know where it is going than where it has been, many of its sensory cells are clustered at its head end.  From these, nerve connections run to clusters of interneurons, pack into groups (ganglia) with short interconnecting processes between the cells within the group and longer nerve tracts leading out along its gut and ultimately to the effectors:  contractile, egg- and sperm producing cells.  These neurons use many of the neurotransmitters that are found in mammalian brains (notably the amino acid glutamate), an indication of how far back in evolutionary terms these molecules were adapted for signaling functions.***

"The evolutionary track I have been mapping," writes Rose, "has led from proto-cells to faithfully replicating eukaryotes capable of responding adaptively to patchy environments, from single-celled eukaryotes to multicellular animals with internal signaling systems, and from these to fully-fledged nervous systems capable not merely constructing action plans, but of modifying those plans, at least temporarily, in response to environmental contingencies.  But we haven't yet arrived at brains.  This must have been the next step along the evolutionary path that led to humans.  Concentrating neurons in ganglia is a way of enhancing their interactions and hence their collective power to analyze and respond to incoming stimuli.  Locating them at the front end of the organism is the beginning of establishing not merely a nervous system but a brain, though head ganglia or brains only slowly begin to exert their primacy over the other ganglia distributed through the body.*** [Turning to invertebrates] although insect (arthropod) and molluscan neurons are pretty similar to human neurons, and the biochemical motors that drive the system -- their electrically excitable membranes and the neurotransmitters --- work in the same way, the organization of the system is entirely different.  In molluscs and arthropods the central ganglion --- the nearest any amongst these huge numbers of species have to a brain --- and the principal connecting pathways between it and other ganglia lie arranged in a ring around their guts.  This is a device that can be seen even in earthworms, and it imposes a fundamental design limitation on the complexity of the nervous system.***

"The development of large brains required two major changes in the construction of nervous systems:  the separation of the nerves themselves from the gut, and the concentration of nervous power.  It also required the first step towards the development of a bony skeleton.  Amphioxus,  small sea-floor fish, is an example.  Less behaviourally sophisticated than octopus or bee, it has a flexible rod of cartilage, a notochord, running down its back --- the forerunner of the spinal column --- with the merit of providing a bracing device against which muscles can pull.  More relevantly for the present argument is that eh major nerves and central ganglion lie in a continuous tube running the length of the creature's body, thus disentangling them from the gut and giving space for growth."

We have not even discussed Panksepp's research yet, but there is much here in Steven Rose's account of the evolutionary development of the animal nervous system that indicates the system of neurotransmitters and specialized receptors found in vertebrates long preceded the development of the brain stem in vertebrates.  And there is a suggestion by Steven Rose that this system was capable of "expressing emotions," although probably not in the same sense that Panksepp intends.  But it would be fair to say that human emotional systems and those of other mammals not only have their origins in vertebrate animals older than humans, but in the earliest forms of life on earth.  This is an anthropomorphic view of human emotions as described by Frans DeWaal in The Ape and The Sushi Master (see June 17, 2010 post).  To be sure, Panksepp is careful to admonish in his discussion of similarities between the neurological systems of humans and other mammals that "similar does not mean the same."  There are similar structures and similar transmitters and receptors in the brain, but their location within the brain may be slightly different or even vastly different, and those differences may result in small or even large differences between humans and other mammals.  But in identifying these similarities, Panksepp observes, as the book's subtitle hints, the neuroevolutionary origins of human emotions.  Panksepp decries the history of human psychological research that declined to recognize emotions in animals.  There is considerable research available today that rebuts that notion.

Panksepp discusses several emotional systems, but central to nearly all of them is what he has labeled the SEEKING system.  And in beginning this discussion, we can think back to Steven Rose's reference to the "goal-directed movement-- of a unicell swimming towards food for instance." 

Panksepp is controversial within the neuropsychiatric community, challenging some of the dogmas of neuroscience and human psychotherapy.  One of the dogmas is reflected in this statement from Rita Carter's Mapping the Mind (see November 6, 2011 post):  "A huge volume of evidence suggests that consciousness emerges from the activity of the cerebral cortex that the particular type of consciousness that includes the sense of self requires activation in the frontal lobes.  Ask yourself this:  Where, precisely, do I feel that "I" am centered?  If you are like most people, you will point to a position just above the bridge of your nose.  It is right behind here that you will find the prefrontal cortex --- the area of the frontal lobe most closely associated with the generation of consciousness.  This region is also responsible for our conscious perception of emotion and our ability to attend and focus.  Most important of all, it endows the world with meaning and our lives with a sense of purpose.  The symptoms of schizophrenia, depression, mania and Attention Deficit Disorder are mainly due to frontal lobe disorder."  Carter's sentiment reflects a view that leads psychotherapists to focus on treating the executive, regulatory capacity of the human brain in the frontal cortex in order to overcome these disorders.  While Panksepp does not dismiss the role of the prefrontal cortex in the conscious life of humans, he does disagree with the directionality implicit in this statement:  for Panksepp, like Antonio Damasio (see April 8, 2011 post) "the generation of consciousness" begins with the evolutionarily older parts of the brain --- in the midbrain, where neurotransmitters are generated  --- as well as the limbic system, which together are at the foundation of the seven emotional systems he describes in Archaeology of Mind.   It is here that the "core self" of consciousness emerges, or as Panksepp calls it, the core affective self.  The symptoms of certain mental disorders, Panksepp believes, are not "mainly due to frontal lobe disorder" but may have more to do with the imbalanced (excessive or diminished) production of specific chemicals in the brain in the more ancient parts of the brain.  And as the previous post suggests, epigenetics provide some explanation in the case of stress disorders caused by early childhood abuse leading to excessive production of cortisol that overwhelms the ability of the limbic system to restore calm. 

The seven emotional systems described by Panksepp (and he does not rule out that there may be more) are these:

The Seeking System.  This does not immediately sound like it describes an emotional system, but clearly Panksepp is correct in characterizing the Seeking System.  This is the system "that allows animals to search for, find and acquire resources that are needed for survival.  Arousal of this Seeking System produces all kinds of approach behaviors, but it also feels good in a special way.  It is not the kind of pleasure we experience when eating a fine meal, or the satisfaction we feel afterwards.  Rather it provides the kind of excited, euphoric anticipation that occurs when we look forward to eating that meal . . . the anticipation of sex . . . the thrill of exploration."  Panksepp refers to the Seeking System as the primary process emotional powers that makes animals into active agents in their environments.  "Among animals in the wild, it is easy to see the Seeking system in action.  Resources are not readily available and animals must persistently seek them out in order to survive.  They must hunt or forage for food and search for water, find twigs or dig holes to fashion sheltering nests.  The Seeking system urges them to nurture their young, to search for a sexual partner, and when animals live in social communities, to also find nonsexual companions, forming friendships and social alliances. . . Although this system vigorously responds to homeostatic needs, to emotional urges and to enticing temptations, it operates more or less continuously in the background, albeit at much lower levels when people and animals are not in any particular need of resources or troubled by problems that urgently require solutions.  This system keeps animals constantly exploring their environments so they can remember where resources are."  Importantly, in Panksepp's view, it is the Seeking System that is the motivator behind the intellectual pursuits of the neocortex:  "the neocortex does not provide its own motivation; the neocortex is activated by subcortical emotional systems . . . the neocortex is the servant of our emotional systems."  It is the Seeking System that urges architects, artists, writers, politicians, and scientists to discover new and better ways to solve problems and express themselves.  It "energizes all human creativity."  Seeking arousal "is an anticipatory gift of nature that provides seemingly infinite opportunities for learning; with the developmental/epigenetic emergence of higher mental processes, it gradually fine-tunes reasonable expectations, working hypotheses, as in the conduct of science."  It is intimately connected with learning, which Panksepp describes as an "automatic, unconscious process that enhances are natural proclivity to engage with the world in ever more subtle ways as our minds mature."  In contrast, affect (behavioral outcomes connected to arousal of instinctual emotional systems) is never unconscious; it is felt.

Chemically, the Seeking System is understood to be aroused by dopamine transmitters, but glutamate, which functions in learning and memory, and neuropeptides such as orexin and neurotensin are understood to activate the Seeking System while dynorphin is believed to deactivate it.  The neurons for these transmitters are found in the midbrain:  anatomically, ventral tegmental area, the medial forebrain bundle, the lateral hypothalamus, the nucleus accumbens, and then running to the medial prefrontal cortex via the mesolimbic and mesocortical dopamine pathways.  "In all mammals," notes Panksepp, "the nucleus accumbens interacts with the medial frontal cortex to promote simple appetitive learning (and addictions).  Because the Seeking System energizes the frontal neocortical regions, especially the medial zones that focus on immediate emotional needs, we are able to devise strategies to obtain rewards and escape sanctions (pain) and other pitfalls.  We remember particularly pleasurable experiences and the possibility of addiction is created.  Dopamine transmitters are associated with drugs of abuse, and when they are overly excited there can be negative consequences from addiction.  On the other hand, when the Seeking System is underactive, depressive feelings can emerge. Humans differ from other animals here in one important respect; the dopamine pathways that energize the cortex are linked not only to the frontal cortex but to other sensory-perceptual cortices in the back of the brain.

The Rage System.  The Rage System needs little explanation:  the foundation of anger and aggression.  What it is not deserves some explanation:  it probably has little to do with war among societies (group aggression), nor is it about predatory aggression such as seeking food.  In contrast to the Seeking System, which is largely a "positive" emotion, the Rage System produces unpleasant affects.  The Rage System is connected to dominance systems in species.  The Rage System runs from the medial areas of the amygdala to the medial hypothalamus to areas of the periaqueductal gray (PAG). As with the Seeking System (and all the other emotional systems Panksepp describes), these are the ancient areas of the brain.  The chemicals that can promote rage include testosterone (known to promote physical aggression in males to a greater extent than females), Substance P (important to pain perception), norepinephrine, glutamate, acetylcholine, and nitric oxide synthases.  The Rage System can be controlled by chemical inhibitors such as gamma-aminobutyric acid (GABA) and oxytocin. 

The Fear System.  Similarly, the Fear System needs little explanation.  Like the Rage System, it is not a positive emotion; it produces anxiety, stimulates flight, fight or freezing.  The Fear System operates between the PAG and the amygdala and it is aroused by external and internal stimuli, notably pain, but some responses appear to be innate caused by hard-wired sensory inputs.  Panksepp mentions rats fear of open spaces, sudden movements and loud noises as example innate fear responses.  But fear is connected to memory as well, and memory plays a significant role in conditioning fear responses.  On memory, Panksepp explains, that learning and memory are automatic and involuntary responses (mediated by unconscious mechanisms of the brain), which in their most lasting forms are commonly tethered to emotional arousal. Emotional arousal is a necessary condition for the creation of fear-learning memories.

The Lust System. The Lust System drives basic mammalian physical impulses (sexual affects) on the one hand and social emotions on the other, which can be both positive and negative.  It can drive anti-social behavior (rape, stalking) as well as building families and promoting other forms of well-being.  In the male brain the center of primary sexual urges is in the medial regions of the anterior hypothalamus, (although Panksepp notes that "the precise brain location varies from one species to another).  Testosterone stimulates pleasure in the male, which activates neuropeptides such as vasopressin and promotes sexual ardor, courtship, intermale aggression and possibly jealousy.  Testosterone also activates nitric oxide in the brain, which promotes heightened sexual eagerness.    In females, estrogen and progesterone (the estrus cycle) controls sexual arousal, but adrenal testosterone plays a role in sexual receptivity.  The Lust System, Panksepp says, "recruits" the Seeking System "dopamine-fueled search for companionship.

The Care System.  The Care System is not universal in the animal kingdom, but nearly all mammals and birds exhibit maternal care for their young.  In fish, the job of tending to a nest of eggs is left to fathers, and the brain circuits that drive this behavior Panksepp calls the Care System.  Panksepp notes that researchers learned of the existence of the Care System in mammals when they discovered that blood transfusions from postpartum female rats to virgin rats would lead to maternal behavior in the virgin rats, including nest building, hovering over young, and gathering the young who strayed from the nest.  Panksepp concedes that researchers still do not which chemicals in the transferred blood interact in the brains of virgin rats to cause these behaviors, but given similarities between the urge to provide Care and the urges underlying the Seeking System, brain arousal from dopamine in conjunction with opioids, as well as oxytocin and prolactin are likely involved.  Panksepp hypothesizes that the evolution of the Care System might be traced back to chemicals found in the Lust circuits of reptiles, such as vasotocin, which has a calming effect and promotes nurturant moods in some birds, and neuropeptides like mesotocin that may have evolved in vasopressin and oxytocin, which is recognized as a key maternal chemical.  The maternal (and paternal) nurturing behavior must be recognized as a critical factor in the development of social brain systems.  Research shows that both oxytocin and vasopressin strengthen social memories and are believed to be promote social bonds among mammals.  (See July 16, 2010 post).

Research on the Care System in rats also reveals evidence of epigenetic changes leading to more prosocial behavior.  Female rats lick their pups during early development and this has been shown to influence the emotional abilities of young rats later in life.  Abundantly licked rats grow up to be less anxious, more resistant to stress, and more capable of exhibiting learning and other adaptive behavior later in life.  These adult rats have diminished stress hormones (corticotrophin-releasing factor (CRF)) and adrenocorticotrophic hormone (ACTH), more GABA receptor cites, which promotes reduced anxiety, and more receptors for glutamate and norepinephrine, which facilitate learning.  Emotionally, these animals are less anxious, showing more activity and fearlessness, and better learning and performance in a variety of fear-inducing situations.  This research could have been cited by Nessa Carey in The Epigenetic Revolution.  (See April 28, 2013 post). 

The Panic/Grief System.  Panic and grief intuitively seem like strange bedfellows but the common emotional/behavioral link in this "system" is separation anxiety, something that is seen across a number of species.  Grief connotes a sadness that arises from social loss; panic connotes a separation from a secure or stable environment.  Immediately, one can conjure linkages between what Panksepp labels the Panic/Grief System and the Care System, the Fear System.  The Panic System is seen in early childhood development over anxiety in separation of mother and child ("Born to Cry" is the title of this chapter), but it has also been found to be less active in adults.  The Panic/Grief circuits are found in several of the same subcortical areas identified with other systems, including the PAG and surrounding subcortical regions including the dorsomedial thalamus, the ventral septial area, the dorsal preoptic area and the bed nucleus of stria terminalis.  Previously identified stress neuropeptides such as CRF and  ACTH, and glutamate (an excitatory neurotransmitter associated with every emotional response) arouse the Grief System.  Imbalances in the Grief System are a key factor in a variety of emotional disorders because so much mental illness, Panksepp notes, is rooted in the incapacity to enjoy the security of warm interpersonal attachments.  Panic attacks, depression, autism, and a variety of other social phobias are part of the Grief pathologies.  The identification of neuropeptides that actually diminish separation distress and mediate the Care System, such as oxytocin and prolactin,and the stimulation of mu-opioid receptors in the brain may have role in treatments of these disorders.

The Play System.  Finally, but not least, something that one might not think of as an emotional system, but Panksepp clearly documents that it is, particularly in mammals: the Play System.  "Physical playfulness is a birthright of every young mammal and perhaps of many other animals as well. . . It is now certain that a genetically determined Play network that mediates positive affect exists in mammalian brains, although many details remain to be worked out."  The Play System is likewise concentrated in subcortical brain regions, intimately linked to the Seeking System: the urge to play is like a type of hunger, and is not necessarily a social need, although it is linked to social emotional systems. Play is linked to the capacity to laugh, a positive emotional affect. Laughter is not merely found in humans, but also noises made by rats, chirping of birds.  Laughter is stimulated early in children, including mimicry.  Like the Seeking System, dopamine, which is engaged during activity that entails considerable positive anticipation and euphoria, is believed to fuel the Play System because it is aroused (correlated) during play.  Play activates sensory inputs, such as touch, which go directly to older midline regions of the brain such as the parafascicular complex and the posterior dorsomedial thalamic regions. 

In the foregoing, I have catalogued for each of Panksepp's seven emotional systems of the brain the suspected chemistries and at the outset I tried to demonstrate that research documents the ancient role of chemicals in the neurological systems of species and their potential link to the development of emotional system.  My objective in this outline is to highlight a point in a previous post about social emotions, including moral emotions.  In his book Moral Origins, Christopher Boehm concludes by saying that in a few generations we "may have identified some of the genetic mechanisms that help us to behave egoistically, nepotistically, and altruistically, along with others that make for sympathetic generosity, domination and submission, and a variety of other socially significant behaviors that are relevant to morality, including our shame responses."  The earlier post (see November 21, 2012 post) observed that "Boehm may well be right that we will identify the genetic mechanisms behind moral and immoral behavior in a few generations, but the roadmap of investigation is already before us and it begins with emotions.  I say this for two reasons:  first, if anything, genes code for our body chemistry; genes may or may not code for specific behavior (moral or otherwise), although I doubt it (see November 30, 2009 post).  But emotions are driven by electro-chemical actions and reactions in our various body systems and ultimately the neurological system leading to our brains, and genes do code for these electro-chemical actions and reactions and genes code for our brain and other body organs.  If we want to understand the genetic basis for moral and immoral behavior we will look for the genes tied to these body systems and the chemistry that drives emotions."   Panksepp's aggregation of the research on these primary process emotions is a good peek into the links between genes, chemistries, and anatomical structures related to emotions.  In addition to linking genes with the chemicals and brain structures that drive these emotional systems, the inquiry contemplated by Boehm would presumably link these seven emotional systems to other more complex emotional systems not considered "primary process" systems,  including the social emotions discussed in the November 21, 2012 post such as embarrassment, shame, guilt, contempt, indignation, sympathy, compassion, awe, gratitude, and pride. 

One cannot help read The Archaeology of Mind without feeling that Panksepp believes he has been walking in the wilderness of neuroscientific research that treats emotional systems as fundamental, more fundamental than research of the neocortex.  While he now believes that Antonio Damasio has joined his crusade with the publication of Self Comes to Mind (see April 8, 2011 post), in which Damasio gave a tip of the hat to Panksepp's research, Panksepp is skeptical of Damasio's earlier somatic marker hypothesis and the assertion that core consciousness (a higher order mapping process outside the subcortical regions) generates inner emotional feelings of what is happening by synthesizing information from maps abut the body and about the environment. As stated earlier, it is the subcortical emotional system that energizes the neocortex, says Panksepp, not the other way around.  Fundamentally, Panksepp believes that mental and emotional disorders go hand in hand and are best understood as a chemical problem, and when understood in that leads to two important conclusions:  (1) that chemistry will have a key role in providing treatment, and (2) it will cause psychotherapists to recognize that treatment must deal with the emotional aspects of the older subcortical parts of the brain.  For Panksepp, the key question for all neuroscientists and biological psychiatrists is this:  "How are raw affective experiences created in the brain?"  The answer he believes will clarify the foundational nature of experience in general as well as affective disturbances.  For example, Panksepp writes, for depression he would ask:  Why does depression feel so bad?  Why does depression hurt?  Why is it so psychologically painful?  What does it mean to experience social pain?  Few neuroscientists have been willing to ask these questions.

One cannot conclude a statement about Panksepp's research without noting what he neither ignores, but nonetheless does not dwell on: the role of the cortical areas of the brain in human consciousness.  When he does acknowledge higher order BrainMind structures, he says this:  "Although arousals of the primary process emotional networks of mammalian brains are intensely experienced by humans and other animals, it is especially important to recognize that the secondary processes of the BrainMind, the basic forms of learning, memory, and habit formation are among the most unconscious 'mental' processes of them all.  Once we understand this, then many of the bizarre and faulty views from psychology's past may be rectified.  For instance, 'free will' is not a figment of our imagination as too many scientists are ready to claim these days.  Free will is a higher tertiary-level neurocognitive function that we use on a regular basis (and quite effectively when we are not too emotionally aroused) for future planning actions.  This is brought out beautifully in the concept of 'autonomy' and 'self-determination' as developed by Ryan and Deci (2006).  However, we cannot readily will ourselves out of underlying emotional turmoil that has been created through the consolidation of maladaptive affective patterns at primary and secondary levels of BrainMind organization.  At primary-process levels of emotional processing there is no free will, there is no 'controlled cognitions.' Neither do the automatic secondary processes of learning and memory functions, that are molded by our wild animal passions developmentally, exhibit free will.  That can only emerge from well-sculpted, deeply reflective, cognitive attitudes."  He adds, "It is surely our vast cerebral 'thinking cap' --- our extensive cortico-cognitive apparatus --- that distinguishes us mentally from our animal ancestors.  That adds layers of complexity that cannot be readily addressed with animal models."  Michael Gazzaniga would agree.  (See September 27, 2009 post). But "language," Panksepp says," our most unique cerebral skill, "emerges through emotional guidance.  Through language, however, we can uniquely study the extended tertiary-process cognitive affective consciousness of humans.  And this is why there continues to be enormous growth in descriptive (ie. nonneuroscientific) emotion studies in psychology (Davidson et all., 2003)." 

And with that paragraph, I pull the next book off of The Bookshelf. 

Nessa Carey, The Epigenetics Revolution (2012)

A recurring theme running through the posts on this blog is the recognition  of a unit of information as the fundamental units of physical nature.  Collateral to this theme: the transmission of information and the avoidance of errors in translation during transmission, whether those communications are at the cellular level or communications among species or between individuals of a species.  (See March 6, 2012, August 15, 2011, November 27, 2010,  August 23, 2009, and August 17, 2009 posts).  A slight change in a unit of information can potentially change the "meaning" of a larger assembly of units of information, things akin to what we might label words, a sentence, a paragraph, an entire story.  Matthew Ridley uses this kind of analogy when he discusses the genome.  (See November 27, 2010 post):

"Ridley calls the genome a book, the chromosome a chapter, the gene a story, an exon a paragraph, a codon a word consisting of three letters, and a base is a letter, either (in the case of DNA) an A, C, G, or T (or U in the case of RNA), for adenine, cytosine, guanine, and thymine, each consisting of one or two aromatic rings and arrangements of carbon, hydrogen, nitrogen, and/or oxygen atoms. These chemical units are the basic units of information that comprise life forms, but alone they do not give rise to life. What gives rise to life is (1) the pairing of these letters along a double helix that makes up DNA, and (2) their subsequent transcription into RNA to form three letter codons, which, (3) are subsequently "translated" into a specific amino acid depending on which three of the four letters are transcribed and their sequence. (4) The particular chain of amino acids creates a protein. By this process, it is said that "genes" code for "proteins." While the RNA amino acid chains may have been the earliest form of life, "life" as we know it received a boost with the creation of cellular membranes to form the first cells that carried the proteins containing genetic information central for the cell's organization. This development is still not fully understood.

"This ability of the genes to copy themselves, read and transmit their story, under the right conditions, is the ability to create another life form. . . . [T]hese units of information [have the ability] to communicate among themselves --- an electrochemical means --- to say "Let's stick together," or "Let's avoid each other," and then to store itself as if in memory. This is what we find in the genome, whatever the species."

"Life began with RNA --- which by itself can replicate itself, and translate and transmit its meaning, as well as catalyze with --- break up or join with --- other chemicals, creating amino acids and proteins. The storage device for these words and paragraphs is DNA. An RNA gene found on chromosome 1 translates the information found in DNA to proteins, which become the primary agent for carrying out the direction specified by the information contained in the genes within a cell." 

A prior post discusses how alterations in the structure of DNA and the chromosome, what we typically refer to as mutations, can lead to changes in species.  (See December 14, 2010 post):

"And there are a variety of mutations of the genetic code. The most common is the equivalent of a typographical error in the process of copying the genetic code --- a substitution of one of the four letters for another. But there are also mutations involving deletions of code and insertions of repeating code or duplications. Sometimes these mutations actually mean something --- changing something about the phenotype in which the genetic code resides, but many, many times these changes mean nothing --- they don't change a thing about how the gene works. Some genes simply lose their meaning over time because they are no longer used, and these are called fossil genes. And some mutations that do have meaning simply do not survive to live another generation because selection is neither accommodating nor forgiving. When mutations occur repeatedly and have meaning --- in the sense that it changes something about the phenotype in which it resides --- and selection favors the survival of that mutation, then given enough time (many generations, thousands of years) we can find new species evolving. Carroll has reduced his mantra of chance, selection and time to this expression: "i) given sufficient time, ii) identical or equivalent mutations will arise repeatedly by chance, and iii) their fate (preservation or elimination) will be determined by the conditions of selection upon the traits they affect."

Epigenetics concerns a molecular examination of genetics, and how substitutions of molecules on a piece of DNA can have consequences for the phenotype of which the DNA is a part.  This does not involve a change in the arrangement of the genetic letters, or the words, or the paragraph or the chapter, in Ridley's terms.  These molecular alterations change the way in which genes are expressed.  Broadly speaking, the "environment" is believed to play a role in these alterations, importantly during embryonic development, but at any stage of life.  And recent research is beginning to show that epigenetic changes can be inherited for a generation or more. The change in gene expression can alter the very nature of cells themselves. 

Currently, there are two fairly well known types of epigenetic modification.  The first is called DNA methylation, which involves the addition of a methyl group (carbon atom bonded to 3 hydrogen atoms) to one of Ridley's genetic "letters" --- cytosine.  The underlying DNA sequence is not altered by the modification.  Cytosine, says Nessa Carey in The Epigenetic Revolution, has been "decorated," not changed.  DNA methylation is associated with genes that are turned "off."  This can lead to a number of disorders that the individual suffers from for the rest of their life.  In addition to turning a gene off, it is also known to prevent messenger RNA molecules from being produced, thus stopping the DNA transcription machinery from working.  The second epigenetic modification is called histone acetylation.  Histone acetylation is associated with turning genes on, although that is not always the case.  Again the underlying gene sequence is not altered.

Understanding epigenetic modifications allows us to better understand why "identical" twins are not identical. It leads to a better understanding of certain disorders (cancer, obesity, and other disorders).  Nessa Carey describes a wide number of research projects in which science is studying whether epigenetic modifications triggers a particular disorder.  I will only discuss one: early childhood abuse triggers an event that has consequences into adulthood; childhood trauma causes an alteration in gene expression in the brain that is generated or maintained by epigenetic mechanisms.  The focus of this research is on a hormone known as cortisol, which is produced in response to stress.  Research shows that the average level of cortisone production in adults seems to be higher for persons with traumatic childhoods.  The hippocampus in the brain responds to stress, and it releases two hormones:  corticotrophine-releasing hormone and arginine vasopressin.  They stimulate the pituitary, which in turn releases a hormone called adrenocorticotrophin into the bloodstream.  When cells of the adrenal gland take up adrenocorticotrophin, the cells release cortisol.  Some of this cortisol makes its way through the bloodstream back to the brain.  Receptors in the hippocampus, hypothalamus and pituitary all "recognize" cortisol and the cortisol binds to these receptors creating a signal to the brain to calm down.  This reduces the production of cortisol and the result is that we are prevented from being overstressed.  Adults who suffered traumatic childhoods are actually overstressed and produce too much cortisol.  Something about the feedback loop that would normally reduce stress is broken.  Research on mice suggests that DNA methylation of the arginine vasopressin hormone leads to increased expression of this hormone and the stimulation of a stress response.  This is all very contentious at this time, and more research is underway on the impact of stress, and other brain-related topics such as memory.

Carey reports on research involving honeybees.  The research is far from conclusive, but there is interest in histone modifications in the control of honeybee development and activity and DNA methylation in the changes of honeybee memory. Carey describes research showing that expression of different epigenetic enzymes varies between different social groups in colonies of ants, and the data suggests that epigenetic control of colony members may be the mechanism that has evolved in the social insects.

In The Social Conquest of Earth, biologist E.O. Wilson referred to epigenetics in an entirely different way.  (September 12, 2012 post)  To determine what evolved that made us humans, he begins by asking "What is human nature?" He suggests that the place to look for the answer to this question is "in the rules of development prescribed by genes, through which the universals of culture are created." Human nature, he says, is the "inherited regularities of mental development common to our species. They are epigenetic rules, which evolved by the interaction of genetic and cultural evolution that occurred over a long period in deep prehistory. These rules are the genetic biases in the way our senses perceive the world, the symbolic coding by which we represent the world, the options we automatically open to ourselves, and the responses we find easiest and most rewarding to make. . . They determine the individuals we as a rule find sexually most attractive. They lead us differentially to acquire fears and phobias concerning dangers in the environment, as from snakes and heights, to communicate with certain facial expressions and forms of body language, to bond with infants; to bond conjugally; and so on across the wide range of other categories of behavior and thought." (See September 17, 2012 post).  Wilson's use of the term epigenetics is more related to the term epigenesis, and this is slightly (although not entirely) different than the study of epigenetics that forms the basis of Nessa Carey's The Epigenetics Revolution.  Nor is Wilson approaching this subject from a singularly genetic angle.  He is concerned with the interaction of genes and culture (broadly considered) in the evolution of a social unit.   I suspect at the bottom of Wilson's use of the term are the neurochemical actions behind learning and memory that triggers epigenetic change affecting the neurological system resulting in  patterns of behavior.  Of interest to Wilson would be social behavior; for example, why do primates groom each other?

Epigenetics as described by Nessa Carey or in the sense intended by Edward Wilson both involve the transmission of information, alterations in the information units transferred, and the effect of these information transfers (positive, negative or neutral). This area of inquiry is a work in progress, and promises to enhance our understanding of disease and health. 

Martin A. Nowak, SuperCooperators (2011)

In 2010, Martin Nowak collaborated with biologist Edward O. Wilson (see previous post) and mathematician Corina Tarnita in publishing an article in Nature entitled "The Evolution of Eusociality." The following year, Nowak followed the Nature article with SuperCooperators; two-years later, Wilson followed the Nature article with The Social Conquest of the Earth.  The cornerstone of the Nature article was its criticism of the inclusive fitness theory, developed by William Hamilton and others, that became the mathematical foundation of kin selection in evolutionary analysis. Kin selection theory became the basis on which the presence of altruistic behavior in nature, a phenomenon noted by Darwin in The Origin of Species, could be explained in evolutionary terms.  One would have thought from the Nature article that Nowak and Wilson were on the same page in terms of their analysis of evolution and cooperation, but the fact that they wrote separate follow-on books reveals significant differences.  While Wilson creates controversy by announcing that he finds little additional value in kin selection theory for evolutionary analysis, Nowak acknowledges the detractors that responded to the Nature article and concludes that kin selection still has some explanatory value.

The discussion of group selection theory and multilevel selection with respect to the social insects in The Social Conquest of the Earth closely follows the summary of "a full theory of eusocial evolution" in the Nature article:  "We suggest . . . the following may be recognized:  (1) the formation of groups.  (2) The occurrence of a minimum and necessary combination of pre-adaptive traits, causing the groups to be tightly formed.  In animals at least, the combination includes a valuable and defensible nest. (3) The appearance of mutations that prescribe the persistence of the group, most likely by the silencing of dispersal behavior.  Evidently, a durable nest remains a key element in maintaining the prevalence.  Primitive eusociality may emerge immediately due to spring-loaded pre-adaptations.  (4)  Emergent traits caused by the interaction of group members are shaped through natural selection by environmental forces.  (5)  Multilevel selection drives changes in the colony life cycle and social structures, often to elaborate extremes. *** We have not addressed the evolution of human social behavior here, but parallels with the scenarios of animal eusocial evolution exist, and they are, we believe, well worth examining."

In their separate books, both Wilson and Nowak address "the evolution of human social behavior" not addressed in the Nature article, but they take divergent paths.  Wilson starts to head down a path I wish he had developed further.  To determine what evolved that made us humans, he begins by asking "What is human nature?"  He suggests that the place to look is "in the rules of development prescribed by genes, through which the universals of culture are created."  Human nature, he says, is the "inherited regularities of mental development common to our species.  They are epigenetic rules, which evolved by the interaction of genetic and cultural evolution that occurred over a long period in deep prehistory.  These rules are the genetic biases in the way our senses perceive the world, the symbolic coding by which we represent the world, the options we automatically open to ourselves, and the responses we find easiest and most rewarding to make. . . They determine the individuals we as a rule find sexually most attractive.  They lead us differentially to acquire fears and phobias concerning dangers in the environment, as from snakes and heights, to communicate with certain facial expressions and forms of body language, to bond with infants; to bond conjugally; and so on across the wide range of other categories of behavior and thought."  This is an important statement, but Wilson does not flesh it out, and he trips when he adds, "the rules of physiological development are not genetically hardwired."  As Sean Carroll's Endless Forms Most Beautiful, The New Science of Evo-Devo explains, the developmental processes of different organisms are genetically determined, including the post-natal development of the organism, which in the case of humans goes on for many years.  Wilson is simply wrong when he says that physiological development is "not beyond conscious control, like 'automatic' behaviors of heartbeat and breathing."  He is wrong when he suggests that physiological development is completely "learned."  Yes, there is a point when learning and culture become more influential, but as early (infant) child development research reports, the earliest form of social communication, mimicry, is instinctive, and it is not learned.

Wilson's reference to "physiological development" may simply be semantical error.  Physiology broadly refers to  "a branch of biology that deals with the functions and activities of life or of living matter (as organs, tissues, or cells) and of the physical and chemical phenomena involved—compare anatomy, morphology."  Sean Carroll's discussion of evolutionary developmental biology focused primarily on morphology, although physiology is understood in its broader context as applicable to everything about living matter that has a genetic correlate. That would include the human brain and the neurosensory system.  Wilson is  thinking about something different than physiology.  He is contemplating behavioral epigenetics, and refers to our innate predispositions to learn and make one choice over another. This is why understanding the human brain and the neurosensory system that feeds the human brain is critical to understanding human nature.  Nor surprisingly, many posts on this blog are devoted to this understanding.  Specifically, human behavior is not genetically determined, as social insect behavior might be genetically determined, but our nature has effectively set us up to receive information (learning, culture) in such a way that is more likely to cause us to behave one way rather than another.  An example of this "predisposition" includes incest avoidance; we have a "bias" against sexual relations with those we have grown up in the same household. 

In terms of social behavior, as I previously mentioned in the prior post I do not think we can understate the role of human memory --- unique in the animal kingdom --- in the evolution of culture.  I also do not think we can understate the role of feelings and emotions either, and my surmise is that there is more than a predisposition here:  human feelings and emotions are hardwired, and they likely contribute substantially to a number of our biases and predispositions.  For example, feelings such as blushing  are associated with social emotions such as shame and embarrassment. These emotions are universal among normal humans.  It is surmised that blushing may have evolved as a means of avoiding conflict by reducing the possibility of deception.  The person who witnesses another blush knows the reaction is authentic and that the person acknowledges he is troubled by what has happened.  Disgust is another social emotion, likely to have evolved as a part of a physical response to offensive foods, is universal among normal humans.  Wilson only briefly alludes to these basic social emotions, but significantly culture has evolved to exploit these emotions so the emotion can be triggered differently among different cultures.   Nudity, for example, may trigger blushing in one culture,and no response in another.  Fear, which Wilson briefly discusses, is another emotional response that has consequences for social behavior, is also exploited by culture.  Feeling and emotion are central components of a biologically based understanding of morality, altruism and cooperative behavior.  These emotions are also related to facial expressions that builds cooperative bonds, as observed by Paul Ekman and Dacher Keltner and reported in the discussion of Keltner's Born To Be Good:  The Science of a Meaningful Life (see July 16, 2010 post):

"'Emotions are involuntary commitment devices that bind us to one another in long-term, mutually beneficial relationships,' Keltner says. Emotions are communicated through several sensory means: visually through facial expressions, which Keltner documents based on his own research and that of his teacher and mentor, Paul Ekman, explaining how muscles in the face are linked to and controlled by neural pathways in the brain that make them reliable indicators of emotion. In facial expression, we recognize embarrassment, which signals our moral sense of wrongdoing and respect for the judgment of others. In facial expression, the smile signals friendly intent and affection among peers and movement toward cooperation and intimacy. In facial expression, laughter triggers mirror neurons in the brains of others that builds cooperative bonds between one who laughs and the other who hears the laugh. Keltner tells us that teasing is not the same as bullying, and is a type of playful communication designed to ferret out another's commitments that bolsters social life. Emotions are communicated through touch, and the skin, our largest sensory organ, evolved to be an important part of social communication among humans and their predecessors."

Emotions also shape our reasoning, undermining the notion that we are purely rational animals. 
(See April 8, 2011 post): 

"Hume's treatment of emotions is not radically different than Damasio's, because Hume's catalog of emotions largely fall under the label of what Damasio refers to as the 'social emotions,' which Damasio believes are of recent evolutionary vintage, some of which may be exclusively human. For both Hume and Damasio, emotions shape our reasoning: 'rational' choice, if you will, is not independent of or from emotions and feelings. Compassion (empathy/sympathy) is one of those social emotions, and compassion, along with admiration, is critical in building a social construct in Damasio's view. And so it is with Hume, as Part III (On The Morals) states that sympathy with public interest is the source of moral approbation, and ultimately reciprocal promise-making behavior and principles of justice: 'sympathy is a very powerful principle in human nature, that it has great influence on our taste of beauty, and that it produces our sentiment of morals in all the artificial virtues.'"

Nowak, in contrast, is less concerned with the biological basis of social behavior, and he is more concerned with the conditions that make social cooperation more likely or less likely than not, and whether those conditions can be mathematically modeled (a game theoretic approach) and tested.  Nowak finds that there are five "mechanisms" that explain whether social behavior is a likely trait that overcomes natural selection's inherent tendency to favor the individual pursuit of self-interest (cheating, defection).  "[N]atural selection favors defectors [over cooperators] . . cooperators have a lower fitness than defectors in a well-mixed population.  As a consequence, as that population evolves, natural selection slowly increases the abundance of defectors until every last one has been exterminated.  This is the 'wrong' outcome, because a population of cooperators has a higher productivity (higher average fitness) than a population of defectors.  Hence, in this particular case natural selection does not achieve the highest fitness but actually destroys what would be best for the entire population.  To favor cooperation, natural selection needs help.  It needs mechanisms for the evolution of cooperation. . . My work show how cooperation arises out of competition, even though the two are locked together in ceaseless conflict.  The collective effort of society depends in part on suppressing the ability of the individual to mutiny and defect.  The same goes for rebellious cells, chromosomes, and genes.  Like day and night, or good and bad, cooperation and competition are forever entwined in a tight embrace."

The first of the five mechanisms of cooperation is direct reciprocity (backscratching) arising out of repetitive interaction.  I will do a favor for another because I expect to encounter that person again and he will repay the favor.  The second mechanism is indirect reciprocity, a reference to the reputation of the person or group (I will do you a favor, and by my reputation someone else will do me a favor).  This type of reciprocity occurs without direct contact.  The other person may be on another side of town or on the other side of the world.  Indirect reciprocity relies heavily on communication to establish a reputation and language capacity is therefore important.  The third mechanism is spatial selection, where natural selection favors individuals who form networks that help each other. The fourth mechanism is multilevel selection, where natural selection favors groups who are more successful in cooperating than other groups. The fifth mechanism is kin selection.  With these five mechanisms of cooperation, "natural selection ensures that we are able to get more from social living than from the pursuit of a solitary, selfish life." 

According to Nowak, what makes humans unique is that we are the only species on Earth that draws support from all five mechanisms of cooperation.  We are the only species that "can summon the full power of indirect reciprocity, thanks to our rich and flexible language."  That makes us "supercooperators."  He adds, "We are now subject to an evolutionary dynamic that can detach itself to some degree from its genetic basis, from chemistry, genes, and DNA.  This is cultural evolution, which involves learning, and explains why we are so devastatingly successful.  As a result, the way the human brain evolves is utterly different from the evolution of any other biological structure that has ever existed.  The architecture of the brain changes every time we talk to another person.  We are able, in turn, to impose structural changes on the way the listener's brain is wired.  The next time you listen to another person, remember that you have permanently changed the wiring of your brain and will do this every time you memorize a moment, no matter how fleeting."  This remark recalls the discussion of how fragile memory is in the September 20, 2011 post discussing Daniel Schacter's The Seven Deadly Sins of Memory.  Equally, however, Nowak demonstrates that notwithstanding a different attitude toward kin selection theory, he really is on the same page with Edward Wilson.  "I do not restrict the use the term 'natural selection' to genes alone.  Depending on whether we talk about cells, animals, or people, reproduction can be genetic or cultural."  If we are speaking in terms of the fact that everything in life is reducible to a unit of information, I would agree that culture can be transmitted.  (See August 15, 2011 post, August 17, 2009 post). And yes, cultures can die and disappear as a result of changes in the environment, as we saw in Jared Diamond's Collapse (see August 12, 2012 post), and Nowak echoes Diamond's concerns when he express concerns about "mankind teetering on the brink of several possible catastrophes of its own making," including nuclear conflagration and the ultimate "Tragedy of the Commons," global warming, which he believes will force humans to enter a new chapter of cooperation.  The question, of course, is how long will take for humans to establish that level of consensus (see August 12, 2012 post).  But I would echo Frans DeWaal:  evolving culture in humans will not contradict what has evolved biologically, it will only support what evolved biologically.