Evolutionary Likelihood

“DNA courses like an ever flowing river down the generations. The river of DNA that flows through us into the future is a pure river that leaves us exactly as it finds us with one exception. There are occasional, very occasional, random changes called mutations. Because of these there is genetic variation in the population and that is what opens the way for natural selection – a world filled with good DNA.”
Growing Up In the Universe, Richard Dawkins

 

I think a lot of us carry a set of unrealistic expectations about how our experiences of body, feelings and mind should be. The idea that others do not suffer the same anxieties we ourselves do is mistaken. Each of us bears our unique habits and preferences, our own hot button issues and our own intolerances yet these all take place against a larger backdrop of what we share in common with everyone else who is having this human experience. Hunger and anger, pride and shame, comfort and anxiety, love and hate all bear a signature that is recognizable however and in whomever they express themselves. Our identification with the characters of theater and movies works because these common, shared human characteristics are so easily recognized.

The question then becomes what attitude will we take towards what we find within the human experience? If you love and care for life as it is, one would do everything in one’s power to nurture and protect whatever life depends on – good food, clean air, and fresh water. Evidently that is not how we feel about this human experience. Evidently, at least collectively, when we see the highs and lows of human nature they frighten and disgust us; we see monsters and animals instead of our humanity.

Contemplative experiences restore the deep mystery of the mind’s awareness to our assessment of human nature. Familiarity with the mind’s vast spaces restores a cosmic dignity to the human adventure. We are children of the stars and do well to remember that, if we are to stay awake to how precious each moment of being alive truly is. I suggest that to appreciate both the fragile nature of the planetary ecosystems on which human life relies and the preciousness of human compassion we need to be thoroughly grounded in evolutionary theory. It provides the modern middle way between the extreme views of an all-powerful creator god on the one hand and blind, meaningless chaos on the other.

Reasoning compliments contemplation. In this instance the reasoning behind evolutionary theory offers a way of understanding where our human nature came from, how it was shaped and formed into what we experience. It is a story of how our very bodies and minds have come forth on a planet teeming with food and challenges. It is your story as you embody yet another expression of the DNA life stream that has run pure for billions and billions of years. The evolutionary perspective can also be used to combat the illusory idea that life should be other than it is. The body, speech and mind that make up the contents of our awareness’ primary experience are not fallen versions of a once perfect, heavenly Adam and Eve but built up gradually, step by step over vast stretches of deep time through a type of exploratory groping through jungles of possibilities – all the ticklishly enticing and equally actual instances of DNA’s expression.

Evolutionary theory takes the steam out of the self-criticisms that arise by expecting ourselves to be something we are not, something other than human. We are working our way towards an understanding of the human mind rooted in evolutionary theory where understanding the forces at work will provide a scientifically solid basis for compassion and empathy. It is easier to have true compassion for oneself and others when the reality of our situation is appreciated. By clearing the deck of ideas such as perfect souls become flawed by sin by being incarnated and human beings purposefully designed deterministically by an all perfect and all knowing designer, we find space is made for nurturing and expressing the value of being a human being on its own terms. The evolutionary perspective also seems critical to me because it removes the narcotic, semi-conscious belief our behavior indicates is widespread; the idea that modern humanity is so special we are bound to succeed. We dare not take it for granted that everything is going to work out fine in the end because some invisible insurance policy is underwriting the human experiment. It is all too easy to allow thoughts of the absolute or ultimate to remove value from the contingent and relative.

That said, none of these comments should be construed as applying to whatever ultimate or absolute may or may not exist. The point is how different views of what reality consists of have implications for how people behave in the here and now. This is more about what is acceptable in public discourse than what one might hold in one’s innermost heart. In public discourse we can expect those involved to appeal only to demonstrably real features of our experience and stick with reasoning for whatever conclusions or explanations of that experience are offered. The likelihood one would rationally assign the hypothesis of a supernatural creator in public discourse changed with the addition of this evolutionary knowledge to our cultural inheritance.

There is no question that evolution by natural selection is a fact of life. Its results are noted in biological laboratories every day. Studying this subject offers an opportunity to exercise intellectual integrity and courage. The reasoning is tight and specifically designed to not depend on any supernatural explanations. Life, which seems so carefully designed for a purpose, is found to not quite be so, not as it seems anyway. These intuitions run counter to much of the philosophical and religious thought within our cultural inheritances. Courage is needed to wield this knowledge as a hammer to tap idols and find which ring hollow but skill is also required if the knowledge is to be effective in conserving what is valuable among our inheritances. This knowledge is a like a sharp sword that while very effective for cutting away ignorance can also cut oneself if we are not careful.

The Reverend William Paley is often credited as representing the traditional view in his 1802 book Natural Theology in which he introduced the world to an (in)famous watch in what has come to be known as the argument by design. The book opens by discussing a man walking along and kicking a rock that then later in his travels coming upon a watch. The rock is a simple object obviously brought forth purely from the interplay of the forces of physics. The watch on the other hand is equally obviously designed for a purpose and whereas the rock could be brought forth by the blind forces of physics, the watch could only have been brought forth by a designer. The good Reverend went on to draw the analogy with the natural world where mountains, clouds, oceans and lands might be brought forth by the blind forces of physics but animals in all their variety and complexity are designed for a purpose and so imply there must be a designer; the Reverend’s creator god.

Hume was the first to point out the argument by design basically shoots itself in the foot. What is to be explained is the order and complexity we find in living things. To propose a designer is just to posit a more ordered and more complex origin since that which could design something as complex as the animal kingdom in all its varieties, including us, must be even more complex in itself. What is posited is no solution to what needs to be explained, it just takes the argument around in a circle.

Daniel Dennett has recently given us a wonderfully picturesque and accurate term for any step in a logical argument that basically just amount to “insert miracle here.” He calls it relying on skyhooks. If building the argument that justifies a large degree of belief in a theory is likened to building a brick building, each part of the logical progression of the argument proceeds by working with what has come before as step by step it progresses to its conclusions. We use cranes capable of lifting the doors and windows of our insights and clarity. A skyhook by contrast attempts to explain a source of design complexity without building on the lower layers. The use of skyhooks is intellectually dishonest.

Though the appeal to a creator fails as a rational argument the very real puzzle remains – animals look “overwhelmingly and compellingly like they were designed.” (Dawkins) Compare the complexity of say a Boa Constrictor to that of Paley’s watch and it is not just more complicated, the Boa is a billion times more complicated. Fred Hoyle, former president of the Royal Astronomical Society, provided a very picturesque illustration of just what it is that needs to be explained. Imagine a hurricane sweeping through a junkyard. The chance of it spontaneously assembling a 747 airplane is equivalent to the chance of an eyeball being formed. Eyes and 747s can’t come into existence by chance, a single lucky shake of the dice, but they can if we spread out the luck. Evolution will then occur if the tiny, lucky steps accumulate. This is key:

Smearing out the luck and accumulating it.

Hoyle’s junkyard hurricane making a 747 drives home the point that chance alone could never produce the complexity of living forms we find on our planet. It is highly improbable, astronomically improbable; in a word it would be a miracle. How then can evolution climb this mountain of improbabilities without relying on a skyhook at any time?

Take the evolution of the eyeball. Eyes have been reinvented in numerous forms by numerous species independently of one another throughout evolutionary history. We can understand how the first step on this design path might be a simple cell that due to a random genetic mutation bears some sensitivity to light. If we imagine this primitive ability to sense light and dark at the base of a huge mountain then the fully formed mammalian eyeball, which is very nearly functionally perfect, would be on the mountain’s peak. On one face of this mountain is a sheer cliff from top to bottom. Jumping from the primitive light sensitive cell to a fully formed eyeball in a single lucky genetic mutation would be like jumping up this cliff. It would need a lucky shake of the dice equivalent to the hurricane producing a 747.

On the other face of the mountain of probabilities, instead of a sheer cliff there is a path winding its way back and forth, leading step by step up to the heights. In places the path might be steep but nowhere is a leap of miracles required. This is Mount Improbable where evolution spreads out the probability. All that is required is that this individual with the light sensitive cell use their limited but potentially useful information to their advantage as it seeks to survive and reproduce. Critics of evolution have asked what good is half an eye. Perhaps the light sensitive cell is just enough to indicate the presence of a predator giving it a slight advantage over its blinder brethren. Over the vast stretches of geological time 1% of an eye is of more advantage than 0%, 1/8 of an eye will prove more adapted than 1/16 of an eye and so on through a gently progression.

It is not enough to have chance find these improbable, but not wildly improbable steps. The results of the lucky break must be retained as per the algorithm: smearing out the luck and accumulating it.

A final illustration well captures the essence of the evolutionary mechanism that allows it to climb Mount Improbable without recourse to skyhooks. This example is demonstrated in the Royal Institution’s Christmas Lecture of 1991 given by Richard Dawkins in part 3, Climbing Mount Improbable. Imagine we have two combination locks. Each has three dials with the numbers one to six etched on them. The first lock is a normal combination lock in that you need to have all three numbers correctly set on the dials for the lock to open. The second lock is different; it uses a gradually opening mechanism so that if you get the first dial correct the lock opens up a little. Set the second dial correctly and it opens yet a bit more and so on.

Because there are three dials with six possible settings each for each lock there are 6 * 6 * 6 = 216 total possible combinations. To open the first lock you have a 1 in 216 chance of guessing right. This is like trying to climb Mount Improbable’s sheer cliff. Opening the second combination lock is a very different affair. To get the first dial to open your luck need only find the one correct number out of six. Do so and the lock will partially open. Additionally, and crucially, once the first dial is correct it remains open so the second dial also only needs a one in six chance to get it right and the same for the last dial. In the gradual combination lock the total number of possible combinations remains 216 but the working out of the correct one explores a space of 6 + 6 + 6 = 18.

Evolutionary action is similar to the gradual combination lock. It smears out luck and accumulates it.

What Evolves

When we ask what evolves we come to one of those subjects where the contemplative’s unique experiential insight trumps a more academic approach. The contemplative does not propose new terms; the difference is in how the meditative states uncover how it feels to relate to what those terms refer to.

DNA_StructureThe academic explanation of what evolves is, for the most part, the genetic code. Each species is carrying their signature bodily form and the DNA from which those forms have developed. The evolutionary development, evo-devo, was touched on earlier. The development process is one in which the DNA codes for how proteins will be created and those in turn become the building blocks of our body, speech and mind. The DNA holds the recipes for the liver, heart, lungs, stomach, brain, eyeballs and all the rest. The blueprint is the genetic code but the code alone is not sufficient to actualize any of the genetic features. The most recent scientific view is nuanced. It recognizes that the code specifies what to make – the form the proteins will take – yet a larger percentage of the DNA consists of genes and their regulatory elements. This equally important characteristic controls how the main production is scheduled, how the processes work together, get organized and become specialized for the task at hand. The study of evo-devo has taught us how the expression of the DNA depends on the environment it finds itself in. Ecology, the study of life in its environment, extends its reach even here. Part of the DNA environment will be the chemical coordinators created by the DNA itself. These are chemical products that are used to regulate when other DNA sequences will become active, effectively managing the production of the biological building blocks.

The subject of genetics has become commonplace in our news and movies. Most educated people have at least a basic grasp of how the amino acid base pairs form the double spiral shape of the DNA molecule. The standout feature of this molecule is its ability to duplicate itself by a process of unzipping one spiral from the other. The all-important environment the molecule finds itself in then supplies the necessary amino acids to complete the pairing process. This creates two double spirals where there was one before. Due to the strict rules governing how the amino acids pairing will take place the second one is a nearly perfect duplicate of the first. The information structure retains its integrity over generations. The luck accumulates.

What is interesting to consider is just where exactly the influence of these genetic operations end. If we can break out of our habitual knowledge of genetics and really contemplate what is being signified behind all the terms and models, the reality of living things becomes magical. Consider this very moment: this little slice of time we label now contains every currently living organism’s vibrational molecular signature in a never stopping dynamic of building, tearing down and transforming simultaneously every biochemical pathway needed to sustain life into the next moment. When we think of DNA the mind tends to isolate a double spiral model but with this thought experiment we are trying to develop an experience of just how all pervasive the magic molecule of life really is. From the grasses in the field to the tip of your nose, if it is organic matter it contains earth’s DNA: the same amino base pairs, the same replication mechanic, and the same dependency on its environment to regulate its expression is found in each and every living thing on this planet. It is the ultimate proof of a shared ancestry, a shared life.

That is one direction we can take to break out of our habitual hoh-hum understanding of genetics: sense its all pervasiveness. Another is to appreciate how the DNA since its moment of inception has never known a moment of death. Yes every vehicle which bears it is mortal through and through but as it itself propagates through the germ cells generation after generation its activities never cease.

The Cambrian explosion is a very educational illustration of just how shared our ancestory is. At that time, roughly 550 million years ago, the trick of DNA replication with slight variations seems to have met just the right conditions to explode into an amazing variety of body forms the likes of which had never been seen before or since.

Burgess500WEBIn Wonderful Life Stephen Gould discusses these Cambrian body forms, known as an animal’s phenotype, at length. It was as if the constraint around DNA’s expression was loosed and for roughly 30 million years it was anything goes at the morphology rodeo. Numerous phenotypes were tried which are no longer around. There were barrel shaped creatures that would not be out of place in H. P. Lovecraft’s Mountains of Madness. The spiny genus known as Hallucigenia hosted skinny legs with claws but, bizarrely, above each leg a rigid cone shaped spine erupted. The Opabinia was a soft body animal which hosted five eyes and a mouth that faced backwards along with a proboscis used, it is assumed, to get food into its mouth. We do not find ourselves in a world filled with descendants of the Hallucigenia or the Opabinia. These were tried but discarded.

All over the planet we are confronted with endless variety of phenotypes yet we find only so many limbs, heads, and eyes – a family of phenotypes we immediately recognize as earth life. It takes the study of something like the Cambrian explosion to appreciate just how arbitrary and contingent these details really are. The pictures of the organisms from the Cambrian era leave us with a sense of viewing alien forms; they lack the signature shapes we intuitively associate with living things on this planet. The phenotype provides another way to break through our habitual model when considering the reality of our experience in the light of genetics.

We have touched on evo-devo, the way in which the genetic code expresses itself through the development of the embryo, fetus and child. With the creation of the body the reach of the genes would seem to be at its end, but is it? Just what is this organism so wonderfully built?

When examining an organism reductive analysis can find aggregates of collections, say all the liver cells in the liver or all the brain cells in the hypothalamus. Looking the other direction, holistically putting all the parts together, we find numerous emergent properties. These are those properties that cannot be found among the parts but only exist as a characteristic of the whole. Among the most important emergent properties of living things are an organism’s behaviors. Among mammals for example, how exactly individuals of a particular species will go about foraging for food is an emergent property of its digestive system, emotional drive system acting on hunger, the homeostasis system maintaining bodily health, muscular systems controlling movement, sensory awareness guiding the movements and some form of an awareness system that can deal with the immediate feedback from the environment it encounters through the senses. This awareness needs to be able to make adjustments and adaptations to stay on track for achieving whatever feeding goal the organism has set out for itself in an ever changing environment. Now ask yourself, ultimately, where did all these systems come from? You will find their roots in the genetic code.

The full blown evolutionary view sees an animal’s many behaviors – and the internal experiences that generate them – and asses them all as an extended phenotype. The beaver’s dam is as much a part of the beaver DNA as is the beaver’s tail, to use the example from The Extended Phenotype where Richard Dawkins first introduced the idea. Everything we call instinctual behavior falls easily into the definition of the extended phenotype. After all, sticking with the example of mammalian species, the nervous system and brain are also products of the genetic code’s evo-devo procedures. The very nexus from which behavior originates is included in the scope of the intelligence we find in the genetic code.

It is indeed interesting to consider just where exactly the influences of these genetic operations end. When we see spiders create a web it is easy to attribute the skill displayed to the magic of instinctual learning. We do not doubt that the information in the genetic code that formed the spider’s phenotype included the details needed to orchestrate the building of the web. What happens when we turn our attention to ourselves?

BrocasAreaSmallThere are organs in the mind and each one is as thoroughly under the control of the evo-devo process as are our fingers and toes. The brain’s ‘organs’ are specialized areas, modules dedicated to particular information processing tasks. Language acquisition depends on these types of specialized areas and shows many indications of being influenced by genetic control. Language, its use and understanding, is associated with the brain’s Broca area whereas written and spoken language is associated with the Wernicke area. Research has shown that human children use these brain centers to learn language. It does not matter which language children are exposed to though it does matter that the language is used to interact with the child. It is as if our brain physiology has primed us to learn language which the human social environment then supplies.

Research has also shown that there is an optimal time for this exposure to occur if the child is going to become fluent in language use. This period of heightened language acquisition ends around adolescence. If a child has not been properly exposed to an environment conducive to learning language by that time, that individual will never be able to become as competent in the use of language as a native speaker. Developmental psychologists have discovered other critical periods where proper environmental inputs are required if the individual is to develop into a healthy adult. All these details are features of an ongoing evo-devo process: careful scheduling of events and adjusting exactly how biological structures will be fashioned through responding to environmental feedback.

Consider again the all-pervasive nature of the DNA molecule but now include the extended phenotype – the flower striving to be sexy for the bee, the bee’s dance communicating direction to the pollen feast and all the other activities of this buzzing, bustling world. Turn the contemplative eye within and spend some time with the dynamics of your internal world. How does learning happen? How can I think ‘my’ thoughts when I have to think them in ‘your’ language? How is it that that which seems most individual about my experience of being alive is so often one of the most collective features of being human? My fear and love, my hope and hurt, my laughter and lust all strike me as exquisitely unique. Yet, in these deepest wells of self, is there not a hint of selflessness? Is it not true that there is a sense in which, as has been mentioned before, life lives us?

Evolutionary Information

Do you wake up sensing vastness?

Unlike the Hindu and Buddhist cultures, the mythic cosmologies of the West lack a sense of vastness. In the East images like Indra’s Net have been used to illustrate existence by likening it to a vast net of diamonds, all reflecting one another just as mirrors in a fun house, where every diamond is a whole universe unto itself. It is a common eastern understanding of existence that it has had no beginning and will have no end so that time exists ceaselessly as universes are endlessly born and die in vast cosmological cycles. Instead of all things being created by a single creator god they recognize a creative ground of all things, gods included. When your eyes blinked open this morning, according to this way of interpreting the experience of being alive and awake, surrounded by mystery, you found yourself again consciously aware in the midst of this vastness of both time and space. The vastness exceeds human thought and imagination in a way not that dissimilar to the vastness we in the West can appropriate by studying astronomy and the ecology of deep time.

I don’t think we properly appreciate the preciousness of what we are putting at risk. A truly heart-felt gratitude for the biosphere and all it offers us requires a sense of just how vast the biological deep time of our planetary evolution actually is. It is important to try and understand viscerally that of the approximately 4 billion years in which life has been evolving, approximately 3 billion of those years were taken up with the evolution of microorganisms, which are still by far the most dominant life form on the planet. It is important to try and understand viscerally that more than 99% of all species that have ever lived are currently extinct, that all the overwhelmingly diverse biological forms we see about us today represent nothing more than the slightest tip of the iceberg.

I see the study of life in the fields of evolution and ecology somewhat like the symbols in the Masonic lodge. All the symbols are there and the terms are accurate but like the neophytes in the lodge we are prone to misunderstand what they mean. We are blind to the real implications of these symbol systems, these sciences, for our lives. Contemplation is our initiatory methodology by which the understandings of the adepts can be acquired. Less poetically: if you really get it, you live it. Climate change is not just a political football and green marketing opportunities. The eco-crises are not just for our entertainment. Something much more powerful is going on here for our species, something involving planet wide forces across deep time and its dream time. Dream time, as I understand it, is like Jung’s collective unconscious or our shared consciousness, or the summation of all that is conscious.  Something like this exists emergent among us since human consciousness is not separate and isolated from the rest of life’s awareness in which it is rooted. In order to tune into that, the small worldview of consumerism needs to be left far, far behind. The heart is noble, yet it remains a choice for each and every one of us whether or not to heed the wakeup call in the age of limits. With evolution and ecology we are in the temple’s Holy of Holies where it would be wise to take off our shoes, for we are treading on our sacred ground.

We have been looking into the ins and outs of evolutionary mechanisms the past few weeks. The recommended contemplations have been around the extent of evolution’s reach, its all-encompassing nature. This has been offered to try and provide us with some felt sense of just how vast the living network of our planetary biosphere really is. Earlier we looked at how easy it is for our minds to form abstractions and generalizations which while helpful in some contexts also blind us to the actual. In nature we find everything is unique and at least a little bit different than its neighbor; every blade of grass, every leaf, every mouse and every elephant. These are the differences that are all important from the evolutionary perspective. To really appreciate what is involved requires, it seems to me, a concomitant appreciation of the vastness of the forms and forces involved. Otherwise our understanding is threatened by an overly simple generalization of the subject which leaves the impression of the biosphere as an unthinking machine.

The metaphor of the biosphere as a machine is a popular one in our culture; it all has to exist for some purpose like a machine and was designed for achieving that purpose like a machine and uses energy to engage flows of inputs to produce transformed outputs like a machine. Enamored as we are with gadgets and machines, when we encounter something like the DNA molecule our default interpretive context for it naturally involves machine-like characteristics. We see abstractions and generalizations where in fact the products are all concrete and specific; there is no turtle, there is only this turtle here, and that turtle over there, indeed it is specific, individual turtles all the way down. Because we see abstractions instead of the particulars which are the abstractions referents these machine like characteristics seem dominant among the evolutionary and ecological processes.

That organisms are the antithesis of machines is of course a bit of a problem for these models. Machines do not learn nor reproduce yet these are the very characteristics defining evolution. Machines do not grow and move through lifecycle stages yet this is the very characteristics defining evolutionary development, evo-devo. With these antimonies in mind what, we might ask, is the reason a machine-like model has been dominant in the biological fields? The answer is doubtless many faceted and complex. The cynic will point out how a model of nature as machine holds out the promise of mankind one day completely understanding and controlling it. Knowledge is power in this model and a machine is theoretically transparent to the understanding. There is some truth in that analysis and it is worth developing. However, there is another similarity I propose is more relevant, namely computing. To appreciate it will require a bit of history.

Darwin’s 1859 publication came on the heels of what historians refer to as the industrial revolution. The discovery of evolution by natural selection occurred at a time and place where applying scientific insight through the technological design of machinery had thoroughly transformed individual lives, societies and both the urban and rural environments in which they found themselves. When Origin of the Species was published there was no clear understanding of how descent with modification happened in living things, only that undeniably it did. By the time the actual mechanism of genetic inheritance was discovered and the structure of the DNA molecule was mapped in the 1950s, the cutting edge of technological development was learning how to produce computers – information processing machines. Here is where I see a metaphorical similarity between machine and DNA processes. The amino acid pairs might be similar to Lego-like building blocks familiar to numerous technologies but it is with the information processing machines that we encounter an almost uncanny alignment of biology and engineering. From the bacterial chemical exchanges to the pulse patterns of the nerve cord we find systems that embody information and assist its exchange have been favored by evolution throughout the animal kingdom.

The evolution of eyes, wings, lungs, hands, skin, skeletal joints, and all the other features of animal physiology are fascinating and full of lessons but I want to focus our attention around the evolution of the nervous system, the information carrying stratum par excellence.PurkinjeCellThe basis of the nervous system is the neuron which is typically formed with a set of branches at one end called its dendrites, a cell body and a single axon. The dendrite tree extends a few hundred micrometers as it branches, whereas the axon of a single neuron cell can extend up to a meter in the human body. There are families of neurons specialized as sensory neurons, motor neurons and interneurons or those which connect neurons together as we find particularly in the brain and spinal cord.

The neuron is a cell specialized to transmit an action potential. The evolution of the action potential occurred in the single celled eukaryotes as they found a quick electrical pulse along their membrane a useful way to activate biochemical pathways within the cell. The details of the voltage gated ion channels which produce the action potential need not concern us here, though it is helpful to know there are two main types. In one a sodium channel is used and the action potential lasts under a millisecond and in the second a calcium channel is used and its action potentials can last 100 milliseconds or even longer. These nerve impulses or spikes travel the length of the neuron’s single axon. The interneurons typically respond to the spike by releasing neurotransmitters which in turn excite neighboring neuron’s dendrites. In this way a signal is sent across the synaptic gap and communication occurs.

The Jellyfish and similar animals use a set of neuron cells structured as a web, a nerve net. With this relatively primitive structure they are able to absorb sensory inputs, process those signals and use them to activate muscles and other physiological processes.  Already in the nerve net the fundamental capability of the nervous system is beautifully illustrated. They provide a window on the world through their ability to sense visual, chemical, tactile, taste and odor signals. There is something very magical about how the senses bridge the inner and outer worlds. These nerve nets also provide the orchestration required for numerous life support systems, from muscle contractions to the production of insulin.

Tinkering with the nerve net over deep time resulted in the development of the nerve cord, what in humans is expressed as the spinal column. With the introduction of a centralizing feature body forms take on the bilateral symmetry that is found extensively throughout the animal kingdom. The phenotype in which the left and right sides mirror each other is constructed around a tube running mouth to anus and a nerve cord with a ganglion or enlargement at each of the body segments.

Bilateral animals can be divided into two camps depending on how this nerve cord is positioned during the early stages of their embryonic development. Early evo-devo expressing the DNA information will position the nerve cord either on the front or backside of the trunk. Insects for example have the nerve cord running along the ventral midline whereas vertebrates have it running along the dorsal midline. Basically the segmented body arrangement is flipped over so where one has the cord running along the back, the other has it running along the belly. There are numerous other features of these two groups’ phenotypes that are also inverted.

HoxGeneRemember the body segments from the fruit fly we saw in this picture when we were discussing evo-devo? The segmented body plan along the trunk of an animal is laid out in the nerve cord through a series of narrow bands. The body innervation pattern follows those segmentations. It is not at all dissimilar to the classic image of the yogic chakra system with the chakras corresponding to the major ganglions.

nadisThe top three segments of the segmented body plan laid out in the nerve cord are what become in modern humans the forebrain, midbrain and hindbrain. We will begin looking into that a bit next week.

The Evolution of Thought

“Of all animals man has the largest brain in proportion to his size.”
Parts of Animals, Aristotle

 

Do you ever wake up sensing nearness?

Unlike the Hindu and Buddhist cultures the mythic cosmologies of the West lack a sense of nearness of the divine. In the East the common greeting is in Anjali; the hands are brought to the heart with a small bow in recognition of the divine in the person you are greeting. In this worldview every sentient being carries a spark of the cosmic, the ultimate. In the West it has been taught the individual has a soul, not quite the same thing at all.

I find this interesting because in my view the most astonishing features of existence are not the far reaches of space or the mind numbing expanse of the universe as a whole. The most astonishing thing is that all this enormous planetary and stellar matter is so very simple in structure compared to organic chemistries. We find the most complex organization of molecules, if you will, anywhere in the universe, to be right here on planet earth. An interesting contemplation is to sense how all the voluminous yet simple matter in our solar system through its gravitational participation is a necessary support of the rich bounty of earth’s fruitfulness. After all, if any one thing was different, all things would be different. That is what it is to be in a universe of total interdependence, a universe like ours.

If we then ask where we find the pinnacle of organizational complexity among organic matter, the brain is said to have no equal. As ‘possessors’ of said brains we are also familiar with their ability to share their thoughts, like we are doing right now.  In Anjali the greeting ritual lifts social interactions to a magical place, one recognizing something like the uniqueness we find in the grey matter. ‘Hello expression of complexity flowering in the universe, I greet you.’ I think it better captures the dignity of an encounter in which the mystery of my awareness touches the mystery of your awareness.

The contemplative has taken their vehicle to be the mind. In Tibetan Buddhism there is the tradition of the three year retreat. Like the traditional Anjali  this too is interesting. It is as if this culture has a tradition of putting the human mind on the altar in recognition of its actual cosmic value. In three years, three months, and three days it is said the yogi can map the mind, familiarize themselves with its outer reaches and in some ultimately inexpressible way, master non-dual awareness. As children of the space age it is easy to feel the real action in the universe is happening somewhere else. With Anjali and retreat traditions we are being asked to reconsider that, invited to consider that we may be looking through the wrong end of the telescope.

Where did these brains come from? How were they made? How do they work? The first and second questions get a rather satisfying answer from evolutionary studies and we will examine them a bit momentarily. The third question is less amicable to the desire for settled answers, though I will suggest modern neuroscience and cognitive science have advanced far enough to send a few popular yet troublingly misconceived ideas out to pasture.

So what is this mind? To begin the story of where brains come from we need to start with the evolution of the nervous system. Whatever else nervous tissue might be it is certainly a means of sending signals. With signals comes information. What is the selective advantage of additional signal processing?

Learning to adapt to the environment through the accumulation of beneficial genetic mutations is a very slow process by our standards. It takes millions of years for speciation to develop and perhaps hundreds of thousands of years for smaller adaptations to establish themselves. In this environment a premium is placed on any developments that enhance the ability of an organism to respond to their specific environment more skillfully.

Early animals evolved numerous sensory mechanisms for reading their environment. The senses that could pick up environmental clues from a distance carried the highest premium of all. To avoid a mortal threat or find a mate, sight and hearing encompass far more of the environment than taste and smell. This was an environment in which the dynamics of predator and prey drove the selection of the fittest for many, though not all, animal species. It is not hard to understand how even the slightest insight into the state of your world would give you an edge; one percent of an eye, when it is one hundred percent more eye than your neighbors have, is of revolutionary importance.

The earliest animals did not have nervous systems. This limited the amount of information about themselves and their environments they were able to make use of. The development of the nervous system took the ball game to a whole new level. Both the speed by which information travels increases and the information density increases by orders of magnitude. The speed comes because the nervous tissue is able to use electrical impulses instead of chemical diffusion for communications. The density comes due to the many connections possible between neurons due to their dendrite structures.

In Dragons of Eden Carl Sagan presented the following graphic as a way of capturing the information explosion that occurred with the evolution of the nervous system. Genetic information tops out (10 to the 10th) but the human brain information content continues an estimated three more orders of magnitude (10 to the 13th).

BrainGeneticInfo2The evolution of nervous tissue would prove to be wildly successful. “Somewhere in the steaming jungles of the Carboniferous Period there emerged an organism that for the first time in the history of the world had more information in its brains than in its genes.”

Another defining characteristic of the human brain is that it has more mass for its body weight than any other animal on earth. Next in line are the dolphins.  This is captured in the brain to body weight ratio. When this is charted Sagan observes the emergence of mammals and primates “was accompanied by major bursts in brain evolution.”

BodyBrainMassRatioSteven Pinker points out the human brain was considerably re-engineered from the primate brain. “Our brains are about three times too big for a generic monkey or ape of our body size. The inflation is accompanied by prolonging fetal brain growth for a year after birth. If our bodies grew proportionally during that period, we would be ten feet tall and weigh half a ton.”

So where did this path to the brain begin? Last week’s post ended with a look at the segmented nerve cord budding into three distinct areas which become the hindbrain, midbrain and forebrain. Remember, we have this DNA expressing itself through the use of its own regulatory genes. The topological mapping of this evo-devo expression in the nerve cord is segmented at one end into these three distinct regions. We can track these regions throughout the vertebrates’ exploration of the DNA’s design space.

The brain of a fish, which isn’t much, is chiefly midbrain with a tiny forebrain. Reptiles and amphibians are the other way around. Another graphic from the same work shows this by illustrating a perch and a toad. Dr. Sagan also included the development of the nerve cord in a reptile, bird and mammal.

SaganSchematicIt is easy to see how the tinkering with the fundamental components has taken place. Can you hear the three part chord echoing through the long centuries?

What we did not know at the time the Sagan book was written is how the regulatory genes actually work. Today there is a rather clear comprehension of exactly which genes are involved. It is an impressive example of information being conserved across a wide spectrum of phenotypes.  In From DNA to Diversity (first edition) the authors summarize the role of the three regulatory genes across the three regions this way:

DNAToDiversityVertBrainFrom the trail of clues left in the DNA evidence the subdivision of the vertebrate brain into fore, mid and hindbrains came before the mammalian neocortex. The last common ancestor had localized, discrete domains of these regulatory gene expressions.

From observation such as these a model of the brain as a triune structure was developed. In this model of the human brain the later parts are added to those that had evolved earlier. The argument for the model relies on the fact that we find some biological elements conserved through evolutionary changes. It stands to reason that mutations that tinker with some of the deepest features of life are likely to be lethal. In this model of brain evolution the early brain parts are left basically undisturbed while the later parts are added.

The oldest strata is said to be the reptilian brain or the R-Complex, to use Paul MacLean’s term. He also refers to a neural chassis consisting of the midbrain and hindbrain. These contain the neural circuitry for reproduction, respiration, heart rate, blood circulation and other systems necessary for self-preservation. They evolved several hundred million years ago. Surrounding that is the limbic cortex which is said to be the seat of the emotions and is associated with the caregiving of the young we find in the mammals. It likely evolved more than one hundred and fifty million years ago. Finally there is the outermost layer consisting of the neocortex which becomes ever more elaborate in the more advanced mammals. It is believed to have evolved tens of millions of years ago, though a leap in its complexity occurred just a few million years ago with the emergence of humans.

In this model the brain consists of three very different modalities, only one of which is graced with speech. Each has its own mentality, intelligence, sense of space and time and its own memory and motor functions. The distribution of the neurotransmitters dopamine and cholinesterase are also found to be strikingly different in each section. We could say the R-Complex is performing dinosaur functions and the limbic cortex is “thinking the thoughts of pumas and ground sloths.”

Culturally we recognize our lower animal nature as reptile-like when we speak of the ‘cold blooded killer’ or when Machiavelli advises his Prince “knowingly to adopt the beast.” It is not hard to recognize the aggressive, territorial, ritualistic behaviors and rigid social hierarchies of the reptiles within our politics of empires and armies.

Care of the young is mostly found among birds and mammals though there are exceptions among the social insects. The development of the limbic cortex is thought to have brought with it these altruistic behaviors. In this model love was invented by the mammals.

With the arrival of the neocortex comes the ability to plan, to think ahead and to consider options. Instead of a potential meal relying only on instinctual jumping or zigging and zagging to escape their predator threat, an animal equipped with a neocortex can also look for an escape route unique to the exact environment in which the confrontation is occurring.

There is something very familiar to western ways of thinking about our humanity in this triune brain model. It is not hard to see Freud’s id, ego and superego in its threefold classification scheme. More anciently, in Phaedrus Plato likened a human being to a chariot being drawn by a set of black and white horses. Popularizers of the triune brain theory pointed out it mapped well to this Platonic insight when the chariot is likened to the neural chassis, the horses to the R-Complex and limbic systems and the neocortex to the charioteer.

The triune brain seems a fairly good model of both brain physiology and human experience. The model is quite popular, quite well known, almost as if it was a theory made to order, one that confirms our expectations. This should make us wary.

Advances in neuroscience have shown the triune model of the brain to be of limited usefulness, even misleading. Just why and what we have found to be the case instead is what we will look at next week.

The Evolution of Feeling

About two hundred years ago a social movement was coming into its own. The movement touched art,literature, history, and the sciences and has left lasting impressions throughout our society today. The movement was in part a reaction to the industrial revolution and the accompanying rationalization of nature. Where the Age of Enlightenment had left many people hopeful that a rational reorganization of human life and society would lead to ever greener pastures, those in this alternative movement saw in these ideals a cold, calculating reason cut off from the ethics and values, not to mention the messy complexity, of real life. The movement was Romanticism which peaked sometime between 1800 and 1850.

Central to the Romantic Movement was a belief that the authenticity of feelings and emotions brought about the most intense aesthetic experiences and in them a truth deeper than reason alone was glimpsed. They were moved by the beauty of nature as opposed to the classical forms and sought freedom from the urban decay of the time through a return to more medieval norms. Highly valuing spontaneity, the romantics also came to value the hero and the heroic who through their deeper penetrations of intuition and emotion would lead society to a better place.

The Romantic Movement provides fodder for great stories full of heroics, dramatic emotional theatrics and lots of Hollywood glamor. The Romantic Movement, while not quite taking over our popular culture, has come close with its worship of youth, getting in touch with your feelings pop psychology and the exaltation of just do it spontaneity. If it recognizes a dark side of living from the emotions, well that is just the price for genius. The romantic ideals are understandable given the highly engineered, overdeveloped world that confronted humanity two hundred years ago. Even more so today when we worry about nature deficit disorder, the Dionysian ecstasies seem to offer a release from the statutes of our overly programmed and controlled lives. Rock & Roll started promising revolution and ended selling Cadillacs. Why?

The romantic notions are a backhanded compliment to the power of knowledge and the splendor of the knowing intellect above the feeling heart. The romantic is playing with the same guild of story elements, accepting all the same basic premises of the Faustian hero. It is simply a reversal of saviors as we find in Goethe’s great poem when love – the feeling heart – leads the magician out of his ignorant hubris that willingly make deals with the devil himself, if only he could possess the knowledge that would give him the power to mold life to his wishes.

The deals with the devil the industrialized world has been willing to make run the gamut from nuclear waste generating activities to genetically modified crops. Pushing science to find the knowledge that has practical applications is our society’s defining characteristic. Those of us interested in what more sane ways of living might arise after the collapse of industrial civilization and helping those who suffer as the slow collapse continues should understand the dominant story. Put simply, there are two approaches to acquiring knowledge and each has its place. In one, the Faustian, knowledge is power and it is sought to aid us in remaking the world as we wish or need it to be for our own survival. The other approach seeks knowledge of the world in itself, to know it more thoroughly so that we can adjust ourselves to its reality. They are the knowings of science and love. As the Francis Bacon metaphors reveal embarrassingly clearly the Faustian approach seeks to storm the castle, put nature on the rack and force her to give up her secrets. The other approach was championed by Goethe where observation of living wholes in their environmental context, in a word systems thinking, is primary and the dissection of dead parts is secondary.

The contemplative learns storming the gates of heaven is ultimately less productive than waiting on the light, seducing the lord to come into your heart. What the Romantics help us see more clearly is how the divisions we place between these forms of knowing are artificial, a construct of our cultural imagination. Those deals with the devil made using the cold hard reason – ‘it’s just business you know’ – we are now coming to understand include very large emotional elements as they eat up what remains of our viable-for-humans planetary systems.

The whole dichotomy between heart and head that the western intellectual traditions had been wrestling with is cast here on the level of social movements. In this view the dark, animal emotions are the chthonic roots of our bodily form while the intellect soars in a realm of Platonic purity. By these lights the human experience is one of struggle between these two contending forces. The mind and body are seen as worlds apart instead of an integrated whole. Descartes captured the essence of this point of view when he wrote, “even if body were not, the soul would not cease to be what it is.” Neuroscientist Anthony Damasio has called this Descartes Error and in a book of the same name lays out the current understanding of the brain-body connection. The state of the art of neuroscience has been finding the feeling element is hardly cut off from our reasoning, quite the contrary in fact. The highest level goals in the brain are set by the emotions and reasoning is not possible without their aid.

The triune brain theory we discussed last week reproduced this whole heart and head dichotomy in a characteristically dark twentieth century way – the role of the heart is played by the reptile. The theory is basically saying the neocortex is where the moral ideals of justice and the powers of reason reside but sadly they are mixed up with the selfish and violent reptilian brain stem, our inescapable fallen nature. The hot, irrational impulses follow biology while the intellect brings us the gifts of civilization. Since the Romantic Movement it has become very common to assume the emotions and the intellect are in separate realms. Steven Pinker points out the dichotomy has also influenced scientific thought in “the id and the superego, biological drives and cultural norms, right and left hemispheres, limbic and cerebral cortex and the evolutionary baggage of our animal ancestors and the general intelligence that propelled us to civilization.”

This triune brain theory rests on a few hypotheses which have not turned out to be the case. First it appeals to the astonishingly conservative power evolution sometimes displays when it keeps fundamental life systems unchanged for billions of years. The features and functions of the brain stem are assumed to have been conserved. The theory assumes the brain stem and its accompanying emotions are hard to reprogram. No doubt there is some degree of conservation around the life support systems found in these regions of the brain but the bulk of these regions seem to have been evolved in step with the development of the neocortex. One example is that the hypothalamus, a member of the older layers, grew in step with the growth of the neocortex. It is also evident that the emotions are quite susceptible to changes and manipulations by evolutionary growth as witnessed in the different dispositions of Pit Bulls and Saint Bernards. Finally modern research indicates that the cerebral cortex has taken over many, if not most sensory and motor functions.

The second hypothesis the triune brain theory assumes is that the neocortex rides piggyback on the older brain regions. Modern investigations have shown that this is not the case, that circuits and signals run both directions. The almond shaped brain module known as the amygdala is well studied. It encompasses many of the circuits that influence the emotions. It receives signals from both the brain stem, as when the body perceives a loud noise and a simple time sensitive message needs to be sent and it receives signals from the cerebral cortex, where sometimes very complex signals are generated from our most refined abstractions. It is well known how thoughts can set off the emotions. Think, for example, of the Dear John letter. Additionally, the emotions help the cerebral cortex as it plots for courtship, escape, revenge and more.

The triune brain theory “promotes the belief that emotions are animal legacies” as Steven Pinker has it in How the Mind Works. The modern view is otherwise. Pinker explains it recognizes the emotions are well designed brain modules that work “in harmony with the intellect and are indispensable to the functioning of the whole mind. The problem with emotions is not that they are untamed natural forces or vestiges of our animal past; it is that they were designed to propagate copies of the genes that built them rather than to promote happiness, wisdom or moral values.”

So if the triune brain model is of limited usefulness what replaces it? There have been many alternatives proffered for why the human brain evolved as it did. Two of the ones on my shelves most impressed me. The first is The Mating Mind, How Sexual Choice Shaped the Evolution of Human Nature by Geoffrey Miller. He argues that our consciousness, creativity, art, and morality were sexual attractors, not just side effects of a larger brain. The other title is The Runaway Brain: The Evolution of Human Uniqueness by Christopher Wills.  He contends that there is a positive feedback loop between human culture and the genes that control the growth and evolution of the brain. Both books are well written and researched and together help overcome the temptation to latch onto a single theory as the be all and end all of the brain’s evolutionary story.

With these couple of recommendations for those who are interested in delving deeper into this subject our conversation is going to shift to what we can learn about our minds from the modern neurosciences. There has been a revolution in our tools for investigating this openly fantastic and complex bit of organic matter we call our brains and nervous systems. The field is enormous. In the coming weeks I hope to share some of what has struck me as the most relevant highlights of the findings for those of us with a propensity for contemplative practices and a heartfelt concern for the ecological health of our planet. There are a number of fertile collaborations between cognitive science and the neurosciences to guide us on our way. Remember the goal of our investigations is a more complete appreciation of the role of compassion in human affairs.

We have already taken our first step along these lines. In Descartes Error Damasio mentions the neurological facts that any theory of self and consciousness needs to be able to take into account. These are among them:

a) Consciousness and wakefulness as well as consciousness and low-level attention can be separated.
b) Consciousness and emotion are not separable.

Concerning point b) Damasio notes this is a “most revealing” fact. Indeed.