THE EVOLUTION OF THE SENSITIVE SOUL: LEARNING AND THE ORIGINS OF CONSCIOUSNESS – Simona Ginsburg & Eva Jablonka (2019)

As with most of my non-fiction reviews, I’ll first give a general overview & appraisal of the book. After that there’s a lengthy section with quotes and paraphrases of stuff I want to keep on record, and those could be of interest to you too.

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What is the mind?
It is the sound of the breeze
That passes through the pines
In the Indian-ink picture.

– Ikkyū Sōjun, 15th century

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The Evolution of the Sensitive Soul: Learning and the Origins of Consciousness is a mammoth: 482 pages of text, 62 pages of notes, 72 pages of bibliography and an index of 28 pages. It took a decade to write.

Eva Jablonka is a microbiologist & evolutionary theorist with a Ph.D in genetics. She is especially known for her interest in epigenetic inheritance, and she co-authored the landmark Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life with Marion Lamb. That book was published in 2005 by MIT Press – with a revised edition in 2014 – and on the strength of this book I’ve added it to my TBR. Simona Ginsburg is a chemist with a Ph.D. in physiology.

The title is a bit misleading in the sense that the moniker ‘sensitive soul’ might sound New Age-ish, but make no mistake: this is as scientific as non-fiction can get. Jablonka & Ginsburg use the term ‘soul’ as an hommage to Aristotle, and the next two quotes elaborate a bit on that, and at the same time set the stage:

The Aristotelian soul is the dynamic embodied form (organization) that makes an entity teleological in the intrinsic sense – having internal goals that are not externally designed for it but that are dynamically constructed by it.

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From an evolutionary point of view, understanding the transitions that resulted in the three Aristotelian goal-directed systems is enormously challenging. The first problem, understanding the transition to the first living system, to the nutritive (/reproductive) soul, is still not fully solved, although great strides have been made in this domain. Very little is known about the second, understanding the transition to subjective experiencing, the evolutionary origin of the sensitive soul. The third, understanding the transition to rationalizing, symbolizing animals, to the rational (human) soul, is one of the hottest topic in present-day evolutionary-cognitive biology, and progress is being made. All of these goal-directed systems are the products of chemical and biological evolution, and there is an evolutionary continuity between them.

The book has two distinct parts: the first a history of the biological conceptions of ‘consciousness’ and some of its philosophical foundations – from Jean-Baptiste Lamarck, Herbert Spencer, Charles Darwin and William James, via Pavlov and Skinner to contemporary neuroscience. The second part looks more closely at major (neuro)biological transitions in the evolution of the mind, and basically sketches the evolution of neural systems and how learning ties into that. It should be stressed that most of the book is about minimal animal consciousness, not about human consciousness.

Instead of trying to summarize the book in more detail, I’ll quote some of the praise I found on the MIT website – and I can say after having read it, none of it is hyperbole. But first let me quote the blurb to give you the general idea:

A new theory about the origins of consciousness that finds learning to be the driving force in the evolutionary transition to basic consciousness. What marked the evolutionary transition from organisms that lacked consciousness to those with consciousness—to minimal subjective experiencing, or, as Aristotle described it, “the sensitive soul”? In this book, Simona Ginsburg and Eva Jablonka propose a new theory about the origin of consciousness that finds learning to be the driving force in the transition to basic consciousness. Using a methodology similar to that used by scientists when they identified the transition from non-life to life, Ginsburg and Jablonka suggest a set of criteria, identify a marker for the transition to minimal consciousness, and explore the far-reaching biological, psychological, and philosophical implications.

After presenting the historical, neurobiological, and philosophical foundations of their analysis, Ginsburg and Jablonka propose that the evolutionary marker of basic or minimal consciousness is a complex form of associative learning, which they term unlimited associative learning (UAL). UAL enables an organism to ascribe motivational value to a novel, compound, non-reflex-inducing stimulus or action, and use it as the basis for future learning. Associative learning, Ginsburg and Jablonka argue, drove the Cambrian explosion and its massive diversification of organisms. Finally, Ginsburg and Jablonka propose symbolic language as a similar type of marker for the evolutionary transition to human rationality—to Aristotle’s “rational soul.”

Here’s Axel Cleeremans, Director of ULB Neuroscience Institute in Brussels, Belgium:

This massive and challenging book is by far the most thorough attempt at exploring consciousness from a biological and evolutionary perspective. Most impressive is the successful integration of philosophical, historical, neuroscientific, and biological considerations in addressing this most vexing question: How and why did consciousness emerge out of biological activity?

Or Jean-Pierre Changeux, honorary professor at the Pasteur Institute in France:

It is the best synthesis I know about consciousness. It includes a fascinating history of the concepts and discoveries about consciousness together with an outstanding presentation of the most recent scientific data, theories and philosophical speculations.

And finally Cyriel Pennartz, from the University of Amsterdam:

Based on the view that consciousness subserves fulfillment of an animal’s needs and goals, Ginsburg and Jablonka take us on an engaging journey from Aristotle to contemporary neuroscience, culminating in the daring but well-informed hypothesis that consciousness coheres with complex forms of learning. This book made me think differently of the Cambrian explosion of life, the roots of animal cognition, and the very origins of human thinking. This accessible and inspiring book offers a wealth of information and deep thought for everyone interested in the rich interface between biology, psychology, and philosophy.

Last year I read Contingency and Convergence: Toward a Cosmic Biology of Body and Mind by Russell Powell, a true intellectual feast. Ginsburg & Jablonka’s book touches on many of the same themes, but frames them differently. Powell’s book is about the nature of evolution, minds, and the possible implications for astrobiology, Ginsburg & Jablonka focus on learning and the evolutionary history of neural systems, including a chapter on jellyfish and the likes that was more informative than Jellyfish by Lisa-Ann Gershwin.

For a wee bit of critique: I would have liked a bit more sections on (the neurology of) mental representation. To me it felt as if Ginsberg & Jablonka don’t fully engage with this part of the consciousness problem, especially as I’ve read Alex Rosenberg’s How History Gets Things Wrong: The Neuroscience of Our Addiction to Stories – a book specifically about that. I would have liked to read the authors’ take on what Rosenberg wrote.

Anyhow, what makes this book a joy to read is its enormous scope, and what makes it truly amazing is its attention to detail on nearly everything it touches: this is no quick pop-science overview of the latest research, no, this is the real deal: interdisciplinary scholarly work of the highest order.

The book is clear and self-contained, and requires no previous knowledge, but at times it is tough reading nonetheless – especially parts of chapter 8 were beyond my level of interest of understanding. This will be different for different kind of readers, but this is obviously an academic book, so your mileage may vary.

Jonathan Birch’s 7-page critical essay on the book in Acta Biotheoretica is well-worth reading, he summarizes it in just two sentences: “Ginsburg and Jablonka’s thesis, in short, is that second-order conditioning involving novel, compound stimuli is a signature of consciousness. This kind of learning cannot happen, they claim, if the stimuli are not consciously experienced.”

If the subject matter interests you, I cannot recommend this book highly enough. Together with How Molecular Forces and Rotating Planets Create Life: The Emergence and Evolution of Prokaryotic Cells by Jan Spitzer – coincidentally about the first Aristotelian transition – it is the best book I’ve read all year.

I’ll leave you with a whole lot of quotes and insights I wish to preserve for myself.

 

SOME TASTY TIDBITS

As in most of my non-fiction reviews, I end with some nuggets of wisdom I’ve learned while reading The Evolution of the Sensitive Soul: Learning and the Origins of Consciousness. The usual caveats apply: these nuggets are not a summary at all, and are not intended as a representative sample of the actual content of the book, although I hope they show at least a part of the book’s wide scope. They are just here as a reminder for myself, and maybe some of them will strike you too. I’ve again decided to quote extensively rather than summarize, to give you a taste of the book’s prose.

I’ve typed about 5000 words of quotes, my lengthiest selection yet, again a testimony to the worth to be found in the book. Here we go:

> “The evolution of symbolic representation and communication, of a new memory system, of the development of a “we” perspective, and of recursive mind reading are therefore of great importance. Moreover, as we see it, the ways in which symbolic language changed the subjective experiencing of humans, including their emotions, are of crucial significance. Humans are not intellectual geniuses with the emotions of a chimpanzee. In profound ways we experience the world differently. The transition to having abstract values (justice, freedom, beauty, and others) that regulate social and individual behavior – the transition to rationality – occurred, as far as we know, only in the hominin lineage.”

> Quite early “mental processes began to be understood in terms of physiological activities of nerves” – by David Hartley in 1749 and Pierre Jean George Cabanis in 1802.

> While I read the book I was truck by a thought of my own: the materialistic/deterministic outlook is a hopeful outlook, because it makes pathways to targeted change possible. How would you try and make a better world if that world & the life it carries didn’t function via deterministic laws?

> Consciousness kinda evolved because possible reactions to stuff become too complex for neural animals. This inflation of the possibility of reactions leads to hesitation (a temporal extension), reactions don’t happen automatically anymore, and this eventually leads to feelings, memory and even reason, which boils down to human consciousness.

> “A second and more convincing observation supporting the causal effects of consciousness is that it disappears with habit. Habit, for [William] James, was a result of the brain’s plasticity (…). The fact that habit simplifies the movements necessary to accomplish an action and diminishes the attention needed for it supports the view that when neural reactions become, through habit, simple and reflex-like, consciousness disappears – it is no longer needed to guide action. A positive argument for the causal power of consciousness is that we are aware of being conscious when we are learning something new or are faced with a difficult decision.”

> William James quotes Joubert about a thought I’ve often pondered myself: “(…) As Joubert says, ‘we only know just what we meant to say, after we have said it’.” Or, as Ginsberg & Jablonka put it: “Thoughts, he suggested, were decomposable only a posteriori.”

> “First, it makes it clear that consciousness is not a state but an activity. Second, it means that we never undergo the same experience twice and that except for the very first sensations just after birth (and as we now know, for some sensations even in utero), there are no “pure sensations.” All later experiences involve memories and past associations, which change from moment to moment. Third, every stream of consciousness contains echoes of the immediate past and reaches into the immediate future. Consequently, subjective experiencing must have a minimum duration – sensations and perceptions must endure for us to actually experience them: “The practically cognized present is no knife-edge, but a saddle-back, with a certain breadth of its own on which we sit perched, and from which we look in two directions into time. The unit of composition of our perception of time is a duration, with a bow and a stern, as it were – a rearward- and a forward-looking end. It is only as parts of this duration-block that the relation of succession of one end to the other is perceived. (James 1891)””

> “It is the animal, not the brain, that feels. The sense of self, most fundamentally of the bodily self, is basic to the animal’s feeling as an agent, and this feeling of self becomes broader and more intricate as mental development proceeds from birth to maturity.”

> “A prominent feature of conscious experience is its serial nature: the perception of one item at a time.”

> “People like the cognitive neuroscientist Victor Lamme think that phenomenal experience is much richer than what can be recalled and reported. They seek a neural definition of consciousness that separates it from attention, working memory, and reportability.”

> “Fear-behavior in the face of danger, [Joseph LeDoux] argues, is more ancient than the feeling of fear.”

> “We know today that the cortex may not be necessary for feelings, rendering these practices [certain experiments on animals] nightmarishly horrifying. Ever since, the term “emotion” has been used by emotion researches to mean the physiological and behavioral expression of emotion or to refer to the action programs that elicit the behaviors. In addition to this historical tradition, it is far from clear that different emotions have much in common – it is not clear that emotion is what philosophers call a “natural kind.” The problem of finding a defendable common denominator for different emotions has led LeDoux to avoid it altogether. He prefers to use instead the neutral term “survival circuits” – brain circuits that are involved in defense, the maintenance of energy and nutritional supplies, fluid balance, thermoregulation, and reproduction. Since we refer to literature that employs the term “emotion” in several nonidentical ways, we use the term “feelings” or “emotional feelings” to denote the subjective aspects and “emotion” (in quotes) or “expression of emotions” when talking about the physiological-neurological correlates, including action programs or brain-survival circuits. Although the study of “emotions” and the study of feeling and consciousness have been largely independent, they have become intimately linked in the work of Antonio Damasio.”

> “”Extended consciousness” is, according to Damasio, the highest level of subjective experiencing, the capacity to connect the remembered past and the anticipated future to the present. It is based on the recall of episodes and on anticipation of the future, and in humans it is related to the autobiographical self; it is the ability of an animal to see itself as the protagonist of the narrative of its own life history. People with certain brain lesions or temporary maladies lose their sense of autobiographical self and cannot see themselves as extended of a period of time, although their core consciousness remains intact. (…) In his 2010 book Self Comes to Mind, Damasio argues that “being awake, having a mind and having a self are different brain processes, concocted by the operation of different brain components.””

> “We must resist the tendency to speak of the brain as an agent that performs computations and makes predictions and decisions, a tendency that reflects the “brain in the vat” approach and ignores the ongoing feedback between sensory stimuli and motor acts.”

> “Lamme (2006) claims on the basis of many similar experiments and various other types of neurobiological data that failures of reportability and failures of consciousness are not identical (…).”

> “In our view, the idea that consciousness is a functional trait like an internal skeleton or an immune system is wrong. Although brains have changed during evolution in ways that have led to the emergence of consciousness (jut as altered morphological organization has led to the development of an internal skeleton), consciousness is not a functional trait. It is a framework for the development of cognitive and affective functional traits. We argued in chapter 1 that a change in the organization of complex chemical reactions and structures generated the first living entities – the first intrinsically teleological systems. Consciousness, we suggest, is more like life than like a skeleton or an immune system. It is neither a property nor a process – it is a new teleological, intrinsic mode of being, its teloi being the ascription of values to encountered objects or states through ontogenetically constructed desires that the animal strives to fulfill. The processes that implement desires and underlie flexible learning have functions. Just as it would be category mistake to ask what the functions of being alive are, so it is a category mistake to ask what the functions of being conscious include. However, it does make a lot of sense to ask about the intrinsic goal of living or the intrinsic goal of consciousness, for goals can be attributed to whole systems, while biological functions are defined as the parts and processes that contribute to the operation of a goal-directed, encompassing system. (…) Consciousness, therefor, introduces an additional explanatory framework, adding one more “cause” to the four causes that Nikolaas Tinbergen listed as necessary for biological explanations. In addition to his phylogenetic (evolutionary), functional, developmental, and immediate (mechanistic) causes, which apply to all living organisms, including plants and bacteria, in (some) metazoans with a CNS [central nervous system] there is a fifth cause – intrinsic motivating subjective experiencing – that is special to them and sets them apart. The addition of a new explanatory framework – function in the case of living things, motivation in the case of conscious animals – is the hallmark of these teleological transitions. With the transition to the rational soul, yet another teleological system and another “cause” emerged, with values and truths becoming function-generating teloi, drivers, and motivators of human action. We interpret Nicholas Humphrey’s proposal that consciousness has created the joy of living and the motivation to live as a way of expressing the same basic idea. (…) As Humphrey puts it: “If natural selection can arrange that you enjoy the feeling of existing, then existence can and does become a goal: something – indeed as we’ll see some thing – you want. And the difference between you wanting to exist and simply having some kind of instinct is that, when you want something, you will tend to engage in rational actions – flexible, intelligent behavior – to achieve it.” (…) But who among animals actually “wants”? Who can be said to have felt needs, which they strive to satisfy? And in what selective context did such “wanting” evolve?”  [These are the final paragraphs of chapter 4, elegantly making the bridge to chapter 5: “The Distribution Question: Which Animals Are Conscious?”]

> “However, the fact that bees, for example, may not feel pain does not mean that they do not have other affective and perceptual experiences – humans with congenital analgesia are certainly conscious and subjectively experience affective states such as pleasure.”

> “[Björn Merker] suggested that consciousness – in the basic sense of subjective experiencing – appeared in moving visual animals whose world was constantly changing and who needed to adjust their body and their goals. The selection of a target in the external world, the selection of a bodily action directed towards that target, and the motivation for that action had to be be integrated (…) To achieve this feat, the brain engages in analog reality simulation of the tripartite interaction between the body, the world, and the animal’s needs (…) There is an implicit “ego center” in this coordinate space, a perspective from which the world is perceived. This ego center creates a motivated “subject,” a “self” located in a body-within-world space.”

> “”Memory” is an umbrella term that covers different relations between past and present/future occurrences.”

> “The formation and maintenance of complex body, action, and world models and distinguishing between self-produced and world-produced sensory inputs involves the binding and integration of world (exteroceptive) and body (interoceptive) stimuli along with models of action patterns (coming from the proprioceptive system) that are constantly updated, evaluated, and compared with past learned memories. Interactions between conspecifics – for example, between mates or other social competitors and cooperators – further enrich the basic perception of the self. The self is defined not only vis-a-vis the abiotic environment but also vis-a-vis self-similar others (e.g., kin, mates).”

> “Ever since Lamarck first pondered the question about why neural organization emerged only in the animal kingdom, the answer generally suggested has been because animals move. All animals that have neurons also have muscles, the only exception being some minute, degenerate, parasitic cnidarians, the myxozoans. (…) Unlike plants and fungi, with their rigid cell walls, animals do not have to rely solely on growth by cell division to change shape and location: the elasticity and contractility of animal cells, notably of muscle cells, enable them to shorten, stretch, and elongate. This type of cell-level movement seems to be a prerequisite for the mobility of all but the smallest multicellular animals. (…) A tiny multicellular animal can move through coordinated movements of cilia, brought about by localized, self-generated, rhythmic motions being transferred among connected cells, but this is impossible when organisms become bigger. When a sizeable, moving, multicellular organism alters its position in space, it moves as a unit, so changes in the shapes and functions of many different cell clusters have to be coordinated. Within a single cell, many molecules act as specific signals, conveying information from one part or organelle to another while chemical signals, such as hormones, are conveyed throughout the body by a circulation system (e.g., the xylem and phloem in plants and the blood vessels in animals). For a large mobile animal, however, this type of signaling is insufficient in terms of both coordination and speed. The members of the two animal phyla that lack nerves and muscles, the sponges and the placozoans, do not face this problem because they are either sessile or move slowly using cilia. (…) Coordination of the activities of the muscle sheets is also crucial for the proper functioning of internal organs such as the gut, whose peristaltic contractions must be synchronized and sequentially organized.”

> “(…) the role of stochastic behavior in the generation of flexible adaptive responses. (…) As shown by the many examples of exploration-stabilization behaviors, from the chemotactic behavior of bacteria to the activities of humans during trial-and-error learning, living organisms employ spontaneous, internally initiated movements to explore their environment, and they organize their behavior by using sensory inputs to reinforce and stabilize some of their actions. Spontaneous, highly variable activity is beneficial because unpredictable movements enable the animal to avoid predators, find new resources, and develop new behaviors.”

> “However, a moving animal faces an immediate problem that if not solved would render even coordinated and rapid movements maladaptive. An animal must be able to determine whether a sensory stimulus is the consequence of a change in the environment or is the outcome of its own actions.”  [This leads to a self and needs a complex nervous system.]

> “The nerve impuls is a stereotyped electrical signal into which all modes of sensory stimuli are translated – photons, chemicals, heat, sound waves, and other mechanical types of energy. This common currency can be used to “map” the external world within the nervous system (…) [and] the internal environment – the organism’s body – within the same system. Importantly, the common currency makes it possible to bind together and integrate different types of stimuli that carry information from a single modality and, even more remarkably, from several different modalities.”

> “The number of messages (and bits of information) communicated within a nervous system at any given moment is simply staggering: even a simple invertebrate may have interconnected networks of several thousand nerve cells, and in humans the number of neurons is on the order of one hundred billion. The flexibility of many of the interactions within neurons and among neurons allows variant local neural circuits to be formed. Circuits can be embedded within circuits, and circuits can communicate laterally, with both negative and positive feedback relations within and between them. Furthermore, organizing circuits  into clusters or centers can contribute to even more efficient integration of information and to better control of movement and other activities. In addition, the neurons’ activation thresholds may be modulated by hormones and by slow bioelectric signals from nonneural cells and organ systems, which are less precise than neurotransmitters in targeting specific cells but are better suited for controlling overall homeostatic states. Order and functionality in such a vast, rich communication system cannot be based on precise instructions; there have to be strategies that make sense of diversity and massive stochastic variability in neural activity, as well as powerful constraints. The nervous system is a spontaneously and inherently active system: even in animals under anesthesia or in comatose states, there is ongoing spontaneous activity. All neurons, at all times, contain incessant electric discharges, and in neurons, as in other cells, are ongoing changes due to the molecular turnover that accompanies and results from chemical reactions of synthesis and degradation within each cells. These stochastic activities occurring between and within nonlinearly interacting neurons generate great diversity. This diversity is the “raw material” that is organized, through the amplification and inhibition of neural activities, into coherent actions and coherently perceived inputs. (…)”

> “The synapse (…) is not the only locus of memory in neurons. Neurons also have epigenetic memory systems both in the nucleus (induced chromatin marks that function as memory traces) and in regulatory factors, such as RNAs and protein complexes, that can be transferred among cells and alter their threshold of reaction. When an animal learns, connections among neurons grow and strengthen through activity and diminish with a lack of signaling. Thus, during the lifetime of an animal, whatever it senses can leave a mark on its synapses and its intracellular epigenetic memory, literally forming tracks of past environmental encounters – that is, memory traces or engrams. Furthermore, repeated encounters with the environment make certain signals and responses easier or more difficult to elicit, and linkages an form between various incoming signals from different sources, thus producing contextual learning.”

> Neurons evolved from molecular machinery (ion pumps) already present in bacteria.

> “There is good evidence that the nervous system is intimately involved in animal embryonic and postembryonic development and growth, and controlling the development and growth of internal organ systems may well have been one of the major functions of the first nervous systems.”

> Sponges might have lost their neural system.

> “But how rich is the actual behavioral repertoire of cnidarians? In the jellyfish Aurelia, which is one of the best-investigated cnidarian genera, fifteen species-specific innate behaviors have been documented. These include swimming upward when encountering either mechanical stimulation or low oxygen; swimming downward when encountering low salinity, touching the surface, meeting with turbulence, or finding themselves in the two top meters of water; swimming away (not necessarily up or down) from rocks and turbulence; remaining in areas with conspecifics; staying in areas containing the smell of prey; and altering, in various ways, their swimming behavior following the capture of prey. Some responses are complex and suggest that discrimination, integration, and action selection are enabled by their nervous system. For example, Aurelia‘s response to touch depends on both mechanoreceptors and chemoreceptors, and its reaction depends on the type of touch. While a touch by a conspecific elicits a pause in swimming followed by a resumption of the previous swimming pattern, a touch by a silicon ball initiates reorientation and swimming upward. Catching prey also elicits different behavior depending on the conditions: when prey is first caught, the speed of swimming increases for a while, but after the animal has caught several items of prey, the swimming speed decreases.”

> There are four major types of epigenetic mechanisms in cell memory, that “are crucial for long-term learning and memory.”

> “According to Holló and Novák, bilateral symmetry maximizes the ability to swiftly change direction because changing direction requires the generation of instantaneous “pushing” surfaces, from which the animal can obtain the necessary force to depart in a new direction. (…) The evolution of bilateral symmetry went hand in hand with the evolution of a single, forward direction of locomotion, with the anterior parts of animals becoming the first to meet or seek various stimuli in the environment (…) which later became a head.”

> UAL has a many benefits: 1) an animal “can discriminate between combinations of stimuli or movements”, 2) an animal can recognize and reconstitute relevant compound patterns “based on partial cues”, “because local circuits, larger networks, and even larger maps are highly interconnected,” and so “a process of pattern completion that induces memory retrieval can occur even when only a subset of circuits is activated”, 3) an animal “can now make an educated guess based on its past experience” because “reinforceable compound patterns become retrievable” and “the animal receives clues as to what to do, since some of the activated engrams are associated with successful exploratory activity toward the attractor-related stimuli (such as food, shelter, and their contexts) or away from repulsor states”, 4) an animal “can make cumulative improvements to cope with novel conditions. They can learn, for instance, how to handle a new food source with increased efficiency, building on less-efficient past practices. Crucially, all these adaptations occur during the lifetime of the animal and are based on selection processes within the individual rather than (only) on natural selection among animals.”

> C.F.A. Pantin in 1965: “The really important first step in the evolution of advanced behaviour is the replacement of simple stimuli or simple patterns of stimulation for the genesis of behaviour, by an abstract model of objects in the real world – that same real world of objects with which our own naïve realism endows the world. The ant reacts to stone and so do we, rather than reacting to the very different initial sensory inputs by which these are detected by ants and men.”

> H.V. Helmhotz in 1867: “Physical activities are in general not conscious, but rather unconscious. In their outcomes they are like inferences insofar as we from the observed effect on our senses, arrive at an idea of the cause of this effect. This is so even though we always in fact only have direct access to the events at the nerves, that is, we sense the effects, never the external objects.”

> “When we think about consciousness and sentience, we do not usually think about learning. What comes to mind are the immediate experiences of seeing a sunflower, of feeling a stab of pain or a flood of joy, of hearing the song of a blackbird, of smelling freshly baked bread, of tasting a ripe banana. These experiences can be fleeting, and we may soon forget them. But how did animals come, evolutionary and developmentally, to have such experiences? As we have argued throughout this book, evolutionary, learning was the basis on which this experiencing process was constructed. There is no point in sensory discrimination in a rapidly yet recurrently changing world if we are unable to remember it and use it to improve our lot. Moreover, we suggest that even fleeting experiences involve processes of stabilization and updating that are intimately related to learning, as is most obvious during early development. A young animal, like a baby, does not come equipped by evolution with ready-made percepts, although it does come with sensorimotor scaffolds on which percepts can be built. A baby learns to see distinct things, it learns to hear discernible voices, it learns to construct a model of its own body as it acts in the world.”

> “Because UAL is based on interconnected activity within multiple networks and maps, it is time-consuming, allowing the representation to persist in short-term memory for a substantial time, which is the basis of temporal thickness.”

> Fire can have a causal & functional correspondence with a neural system (the reflex), it can have a neural representation (via Limited Associative Learning), it can have a mental representation (the idea of fire in the mind) and it can have symbolic representation (language).

> “In all these animals, the default, spontaneous, exploratory activity that led to the distinction between the self and the world was rewarding (maybe even joyful, as Humphrey suggested), encouraging the animal to engage with its world. As Aristotle suggested humans (and we extend this to other conscious animals) take delight in perception for its own sake because our senses and especially sight “makes us know and brings to light many differences between things.” Experience then brings joy because it leads to knowledge through learning, a high-level CSS [categorizing sensory state]. Exploratory activity was positively valenced because exploring animals had more learning opportunities and could adjust to the world by learning. We therefore see the SEEKING emotional system described by Panskepp (…) as reflecting animals’ intrinsic motivation, exuberantly exploring their world. However, unlike Panskepp’s view of the evolution of (affective) consciousness, which suggests that primordial emotions preceded learning-related emotions, our model suggests that learning appeared long before basic emotions and drove their evolution.”  [For more on Panskepp, see my review of The Emotional Foundations of Personality: A Neurobiological and Evolutionary Approach by Panskepp & Davis.]

> “Building on the functional architecture of UAL, millions of years later vertebrates, cephalopods, and possibly even some insects evolved imagination, dreaming, and the capacity to plan and flexibly choose among alternative future actions. These animals, too, had to “pay” for their ability to select internally, which, as Popper put it, “permits their hypotheses to die in their stead.” In these “Popperian organisms,” selection for ameliorating the potentially confusing effects of imagination and dreaming led to self-monitoring and to the further control of memory, forgetting and emotions.”

> “The causes of the Cambrian explosion have been sought in tectonic, geochemical, climatic, and biological processes, and the results of studies from all these perspectives paint a picture of the Cambrian as a unique junction period, with different and interacting factors contributing to the explosion. The climatic and geochemical factors include biologically significant increases in oxygen concentration, beginning approximately 635 million years ago, which led to the diversification of the Ediacaran fauna and the appearance of the first calcifying metazoans approximately 548 million years ago; pulses of global warming, the result of methane release associated with polar movements, which led to increased nutrient cycles and productivity; and changes in sea level that led to the flooding of continental margins, which greatly increased the range of habitable shallow-water areas and led to the rapid input of erosional by-products that brought about changes in the chemical constitution of the oceans, including an increase in calcium [“the lengthy pre-Cambriam erosion of rocks and soils, which lead to a threefold increase in the concentration of calcium in the seas”] and phosphate concentrations (the permissive conditions for biomineralization, which animals exploited [e.g. with skeletons]). All these factors interacted and had effects the were crucial for the occurrence of the Cambrian explosion. However, these global processes do not explain the special features of the dramatic morphological diversification within the animal kingdom.”

> “The transition from the nearly two-dimensional, mostly benthic existence of the pre-Cambrian animals to the three-dimensional world of burrowing and swimming creatures opened up enormous ecological opportunities. This transition would not have been possible without a throughput gut, muscles, an internal or external skeleton, and a CNS that could coordinate internal movements and locomotion. Although all these aspects of animal morphology are crucial, we would like to highlight the role of the CNS [central nervous system].”

> “[Nelson] Cabej points to the CNS’s control of adaptive behavior, such as predatory or reproductive behavior, and dwells on a crucial and little-appreciated factor: the effect of the CNS on morphology and cell differentiation. He points out that once the maternal resources that are deposited in the egg and control the first stages of development are exhausted, ontogeny in neural animals comes under the control of the nervous system. The development of muscles, the circulatory system, and the gastrointestinal tract, as well as the processes of regeneration and the switches between discrete developmental stages (e.g., switches between larval and mature morphologies) are all regulated by the CNS. The regulation of development and morphology by the CNS is therefore a key to understanding the evolution of morphological diversity. We agree with Cabej that the evolution of the CNS was an important factor driving the Cambrian explosion, but we add to his proposal the more specific suggestion that it was the evolution of AL [associative learning] (which was dependent on the evolution of the CNS) and, in the arthropods and vertebrates, of UAL, that spurred the evolution of animals during the Cambrian.”

> “Why did the morphological big bang stop? Stuart Newman and his colleagues have emphasized the importance of the contstraints imposed by the physical nature of multicellular animals: viscoelasticity and chemical excitability that leads to the self-organizing and interacting processes of free diffusion; immiscible liquid behavior; the oscillation and multistability of chemical states; reaction-diffusion coupling; and mechanochemical responsivity. These physical-chemical processes lead to a restricted number of morphologies that correspond to the hollow, multilayered, and segmented morphotypes seen in the gastrulation-stage embryos of modern-day metazoans, which are the basis of all subsequent evolutionary variations. We believe that the evolution of the CNS and AL imposed additional developmental constraints as well as affordances on animal forms.”

> I knew of a bird that makes art – the Vogelkop Bowerbird – but in 2014 a fish that makes art was discovered as well: the male white-spotted pufferfish, which makes “large geometric circular structures on the seabed to attract females.”

> Learning and perception obviously lead to stress too.

> “Given the universality and inevitability of stress, it is not surprising that the stress response is based on a highly conserved network of cellular reactions and factors that can be found across all kingdoms of life. (…) Like the other stress-managing systems, immune systems, which cope with pathogens and other damaging factors, are present in all living organisms and include both innate responses that evolve on the phylogenetic timescale and acquired responses that cope with specific challenges and evolve at the ontogenetic timescale. Crucially, all these factors and systems are intimately involved in learning and memory. In all neural animals, the stress responses involve an interaction between the neurohormonal system and the immune system, two systems that show amazing similarities and interact with each other. Enzo Ottaviani and his colleagues point to four major types of interactions between the two systems: “(1) molecules usually described as hormones and neurotransmitters also bind to specific receptors on immunocytes and modulate their activity; (2) soluble products of the immune system (i.e., cytokines) can act on cells of the neuroendocrine system, modifying the latter’s functions; (3) immune stimuli and hypothalamic releasing hormones both induce lymphoid cells to synthesize neuropeptides that, in turn, might influence the activity of the neuroendocrine system; (4) cytokines and cytokine-like peptides that are potentialy able to modulate immune cell activity are produced by cells of the nervous system.” The similarities and the interactions between the immune and the neurohormonoal systems are so close that the distinction between hormones, neurotransmitters, and cytokines are open to debate, as are the distinctions between immunocytes and neuroendocrine cells. The close connections between the systems have led to the repeated suggestion that neurons and immune cells evolved from a singel multifunctional cell type and their communalities are the foundation for their close interactions during neural development and learning.”

> “It is likely that AL [associative learning], which evolved in Cambrian metazoans, induced chronic stress due to overlearning and led to the coevolution with AL of the stress response and forgetting. The neuroendocrinologist Robert Sapolsky described the well-managed stress response in mammals as the reason “why zebras don’t get ulcers” (the title of his book on the subject), in spite of the presence of menacing predators. He showed that if stress cannot be managed efficiently, it results in immunosuppression, sickness, and weakness. (…) The Cambrian probably witnessed the frist nervous breakdowns (…). Mechanisms at the cellular, neurohormonal, and immunological level that restricted the duration and extent of memory, that promoted active forgetting, and that controlled and limited arousal must have been selectively very advantageous for both the mental and physical health of the animals.”

> “It was in the Cambrian, we suggest, that the great war of nature began to involve suffering – the subjective experiencing of anguish and pain. It eventually led, somewhat paradoxically, not only to dreaming and imaginative animals but even to animals that collectively build utopias of a life without suffering.”

> “Crucially, the epigentic mechanisms of cell memory are very ancient; they precede the evolution of neurons and are found in all living organisms. And so are simple forms of learning. Nonassociative epigenetic learning is the likely explanation of many behaviors of protists such as paramecia. (…) Furthermore, even pea plants can learn by association! They learn to grow toward the direction of a breeze (a conditional stimulus, CS) that in the past was associated with a source of light (an unconditional stimulus, US).”

> “According to this tradition [Richard Semon, Lamarck], memory and heredity form a continuum, and heredity can be conceived as a form of unconscious memory.”

> “Constructing conscious robots will invert the evolutionary life-to-consciousness continuity. Once a robot is conscious, it seems that it will also be alive. Consciousness may therefor render a nonliving entity alive. (…) It may not be life as we know it, but conscious robots will have an embodied cognitive organization that generates a self-maintaining, autopoietic “self” (…).”

> “It is the normative, collective aspects of language that make the world objective. (…) Michael Tomasello ties this objectification to the growth of human cultural groups (…). [It] is related to the evolution of the human social emotions of guilt, pride, shame, and self-deception, which were expressed when the individual became exposed to the actual or internalized public “gaze” that was objectified as a binding societal and moral law. It led to a new type of self-monitoring that reinforced the feeling of having a self, a self that internalized the norms of the society in dialogue with itself, having what we call “inner language.” This self-monitoring enabled the development of autobiographical memory, which partially solved one of the new problems that language introduced (…): the problem of distinguishing between what one was told about and what one imagined on the basis of personal past experience.”  [For more on Michael Tomasello, read my review of his Becoming Human: A Theory of Ontegeny.]

That’s a wrap!

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If you want more, here’s a 55-minute partial summary of certain sections of the second part of the book by Eva Jablonka herself, on YouTube:

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