ORIGINS AND STRUCTURES OF THE HUMAN MIND
How do we get a sense of the whole when we think about our minds, brains and consciousness? We must look beyond what we see as we look at a living adult brain - understanding how and what it does is enormously enriched by understanding how it got to be that way, why it is there, what problems it was designed to solve
The little grey cells between our ears have a very ancient origin, the basic design of our brains was crafted long before there were humans and language.
And, the brains we each have grown are crafted not just by our evolutionary history but by our environment during development.
-We want to understand, not just because we are curious about what goes on between our ears and how it got to be that way, but also because insight into how our brains work can change the way we experience and think about the world. Understanding how our brains work has the prospect of freeing us from some of our more primitive and paleolithic behaviors, behaviors that still are dominant in affairs of politics and state...behaviors that may lead our species to do itself in despite its advanced intelligence.
Let me give you a takehome message, to start this talk at its end: That each of us is a modular society of mind. There really isn't one "I" in there that corresponds to our subjective experience - the "I" emerges from our evolutionary history and the details of how our brains form as we grow up in a particular natural ecology and cultural setting.
First I want to talk about where our minds came from.
Part 1. Evolving mind
we can consider with three aspects of mind and brain evolution:
a. the time scale
b. changes in the hardware
c. changes in the software.
1a. The time scale of evolution
Here we are sitting in this room very much in the present, and I think it helps to start off by dialing to most cosmic time scales, starting with a time before there were any minds as we know them.
We mostly think about minds as what we've got right now, but it helps to think about building minds up step by step, to get more of a fix on how distinctive what we have is compared with the mind of a sea slug or a monkey.
We're on a planet that has been around for about 4.5 billions years
Put that on a calendar year:
-bacteria appear in March. 3.5 billion years ago. most of history of life has been of bacteria.
-our vertebrate evolutionary line diverged from the invertebrates over 600 million, maybe a billion years ago when our common ancestor was a simple worm, the inverts invented complicated brains too, researchers working on octopus behavior say it is almost like working with individual cats and dogs, they have different personalities, and recognize different humans, they exploit very diverse environments.
-in early Nov. 570-550 million years ago, the Cambrian explosion, the basic leggo kit in place. The Cambrian explosion actually has been oversold, recent work in evolutionary developmental biology suggests that divergences in body plans began well before that, and also that chordates were a lucky accident. Role of accident and catastrophe in evolution: If you had been a species confined to the Yucatan peninsula 60 million years ago when the comet hit that ultimately led to the disappearance of the dinosaurs, you wouldn't be around today.
-Over the geological time scale there have been at least seven major extinctions that wiped out 90% of the species present, our current wave of `anthropogenic' extinctions is unprecedented in its speed.
Why am I talking about this?
-We have the same sets of building blocks and switches, the same toolkits, as other living things
-similar sets of genetic lego blocks are used in invertebrates and vertebrates, the gene that says "make and eye here" is similar in both.
-look in the heads of lobsters, monkeys, humans, they all have the same little grey cells, the basic hardware tells us nothing about the distinctiveness of being human, its in the wiring diagram and its plasticity that we seem to have stumbled onto something that no other creatures have: The specialization of being self consciously cognitive, rather than doing echolocation like bats or celestial navigation like birds, or sonar like dolphins, all of these being performances whose complexity you could argue approaches our linguistic abilities.
-let me continue to bring us forward on a time line to get to humans.
-dinosaurs December 10-25, mammals last 4-6 days, social primates Dec. 30-31,
-first hominids, afternoon of Dec. 31, 3-4 million years ago, we appear 11:45, all recorded human history in last minute.
-Now, before I go too much further,
-let's ask what is the job of a behavior, or a nervous system: to decide "what do I do next" in the service of reproduction and getting my genes passed on.
-the idea of the Darwin machine
-What's the decision being made? whether to go for it or avoid it.
-There is a fundamental theme playing out here from the behavior of the simplest bacteria (describe chemotaxis) to our own complicated brain.
-appetitive engagement vs. withdrawal. Is it OK, is it not OK?
-Our whole nervous system, our brains, the brains of all animals, are organized around this question.
-Spread throughout our vertebrate bodies, and orchestrated by our brains, is a complex autonomic or automatic nervous system whose two major components reflect this OK, not OK, appetitive versus apprehensive distinction. Our sympathetic nervous system becomes active during mobilization of our resources when we need quick energy to response to a possible crisis. Our parasympathetic nervous system becomes active when we chill out, it is the restorative part.
-In our daily life we are playing out shifting amounts of these different activities
******1b. - THE EVOLUTION OF OUR BRAINS *****
-Now, what about the hardware of our brains, right now, what is the presence of the past as we sit here.
-At the deepest level of our brains there is a stem, a brainstem (medulla, pons, and midbrain) that appears over 500 million years ago, containing structures that comprise most of a reptiles brain, and indeed resembling our brains when they are only 45 days old. This part regulates basic functions like breathing, heart rate, body temperature.
- This is an old system that regulates basic aspects of survival fighting, fleeing, feeding or fornicating.
-On top of this peripheral nervous system and brainstem, then, you could say we have several different brains layered on top of one another.
-A primitive mammalian brain is central in generating our primary emotions and also is needed, interacting with the cortex, for our more subtle feelings of goodness and badness.
-It is usually called the limbic system, is layered on top of our reptilian brain. Parts of this limbic brain, together with parts of the brain stem, make up a mesolimbic system that regulates appetitive behavior (and, in humans, drug addiction).
-This lower limbic brain is much more of the cortex in simple mammals like rats than in us. It is part of the memory system that both they and we use to store knowledge of different places, particularly ones to approach and ones to avoid (food vs. predators).
-Emotions as organizers, focusers. What the hominid brain has done is send cortical projection back down to the lower centers, much more potential for `top-down' regulation of what in apes, monkeys and lower mammals more autonomic pathways. The hominid cortex also has a lot more involvement in managing voluntary movement than the anthropoid cortex, especially hands.
-As mammals get more social new demands are put on memory as reciprocity evolves, an increasing number of individuals is recognized and a record of who cheated and who did not must be kept. This may be the reason for the increased area and folding of the cortex, more space was needed to store all this information.
-nobody really agrees on why we have big brains, big thinking brains for cognition, for passing on information about kinship, culture , and techniques, I think the most plausible idea is that the invention and use of symbols and language was the engine driving all of these, especially the disproportionate enlargement of our frontal lobes in the transitions from australopithecine through habilis and erectus to archaic and modern sapiens.
*****1c., ANIMAL MINDS, STAGES OF HUMAN INTELLIGENCE. *****
-Now, what were these brains thinking, what kinds of minds do animals have, how are ours different.
It seems to me that the direct and unreflective kind of experience we would call sensation such as what it is like to taste an apple, is likely to be ubiquitous among higher vertebrates.
-Direct experimental measurements demonstrate that we share with many animals the faculties of awareness, perception, attention, orientation, movement, memory, learning, thinking, emotions, energy, and mood.
The content of their consciousness or ours at any given moment consists of the brain's awareness of a small fraction of what these faculties are doing. These contents change continually, depending upon demands of the current environment.
It is reasonable to suppose that there is a sort of consciousness comprising all these elements that we all share,
-but which might not require such things as a sense of self, language, or strategic planning. These add-ons are characteristic of our more complicated human version.
-But what about all the incredibly human like things that animals do? Elephants crying after being punished for stupidity, or of the astounding array of human-like emotional behaviors that have been documented for chimpanzees?
On the one hand we cannot show that the attribution of human traits such as intentionality to these animal behaviors is incorrect, and it is a convenient way to organize descriptions.
On the other, however, if a "killjoy hypothesis" can explain a behavior without reference to higher order intentionality, symbol manipulation, or a theory of mind, the burden of proof lies on the more complicated explanations. Mimicry, memory, and indexical pointers might be sufficient to generate very human like behavior in animals.
The problem with virtually all of the popular accounts of love, hope, fear, grief, joy, rage, compassion, shame, etc. in animals is that possible killjoy hypotheses that attribute these behaviors to something like simple reflexive conditioning have not been tested and ruled out. Rather, we make an "explanation" by attributing human traits to animals. Anthropomorphism.
-Getting back to the thread of what we share with animals,
Think of yourself in moments of blank present centered awareness, you're not thinking thoughts, using words, planning futures, thinking about pasts.
-this may be as close as we can get to imagining what the mind of monkeys, or dogs, cats or birds might be like.
-This episodic intelligence is what I am attributing to monkeys and apes, and it is with the anthropoid apes that the question of selves and others, and theories of mind, come into sharpest focus.......is there continuity or chasm between anthropoid ape and hominid cognition.
-Apes and 18 month old humans are unique in their responses to their mirror reflections.
-the minds of animals, selves and others ,
-mirrors (human infant about 18 months realizes self in mirror),
-theory of mind tests with two trainers, tests of seeing is believing not working with chimps.
-humans, between ages of 3-5 change their performance on "false belief" test...box with crayons example.... Autistic children apparently do not have the brain modules that permit theory of mind development......
-Getting on to our hominid ancestors, we have several distinct kinds of intelligences, associated with development of our huge cerebral cortices that encapsulate each other, that recapitulate our evolution.
-starting with a base of episodic intelligence, cognition, memory, but no `thinking about' foresight, no long term projects, what do we add on?
-WELL, THINK OF YOURSELF IN MOMENTS when just your presence with another human is communication. body language.
-mimetic intelligence, facial muscles, homo erectus, two million years ago, kinesic communication. Communicating how to information by role playing, the game of charades, Human infants do role playing games, chimps do not. Extra linguistic features of our modern minds, a deaf mute without sign language can communicate symbolically and rather completely complex intentions and sequences.
-in this kind of intelligence things are referenced by icons and indexing or pointers...the seminal invention distinguishing hominids the discovery of the utility of symbols. Many think to denote and deal with kinship, clan relationships, and food sharing, which became much more complex with the invention of simple cutting tools and fires for cooking meat.
-Now, think of the sharing made possible by the invention of symbols, and then language, telling stories, making a mythic account of the origin and ends of things.
-mythic intelligence, evidence for language instinct, totally different from animal communication.
-extremely complex pagoda tree of human evolution, one small group from africa wins out. We are all descendents of small group of humans, maybe as few as 10,000 who lived ~100-200 thousand years ago (but, there is debate over this simple model, multi regional hypothesis). Success of this group may have been lucky accident. Basically, modern humans emerged 150-200 thousand years ago.
-There has recently been an effort to document human universals (styles of cooperation, detection of cheating, altruism, hierarchy, competition, male/female behaviors, mate selection, genocide, xenophobia, biophilia hypothesis (liking landscapes resembling african savannah, an unprovable just-so story).
Studies on child development across cultures suggest we come with an innate capacity for an intuitive or naive physics, biology, engineering, math, psychology, and language),
-Genetic evolution that contributed to forming these universals stopped or vastly slowed with the invention of agriculture and cities, as cultural transmission of change almost completely took over. Genetic selection for things like disease resistance, conforming to ambient sunlight levels, etc. has continued. Over the last 10,000 years many groups of humans have developed a totally new theoretic intelligence, this happened as a small fraction of the spoken languages developed written forms, and with the invention of external archives for memory storage, libraries and the world wide web.
-It is a transition that has left us with modern minds in paleolithic bodies having many routines, especially some emotional repertoires, that are irrelevant or destructive in the modern context.
-Our physiology, our autonomic nervous system evolved in a context that permitted robust engagement with myths, storyline, and purpose, as well as by mimetic exchange and physical contact, things that are sometimes hard to come by in these relativistic modern times.
PART II - OUR DEVELOPMENTAL HISTORY
-Now, having done a thumbnail sketch of evolution let me move on to talk for a minute about developing brains.
-We can't think about modular models of the mind without considering their development.
-The main message of this section is that, starting with some default wiring, we actively grow and discover the modules of mind that are permitted by our evolved genetic template - modules that are universal across all human cultures.
We have an amazing plasticity that can wire our brains to fit the world they actually grow up in.
-and so, we, along with cats and monkeys, wire our visual cortex according to visual world we actually encounter,
-we show this by looking at the effect of distortions, starting from balanced but crude template, as of visual cortex, ocular dominance columns, world of vertical lines example.
-demonstration of plasticity by lesions, examples of plasticity of cortex, responding to labelled inputs from thalamus
-during development there is segregation of competing language-related functions that displace each other into the cortex of opposite cerebral hemispheres.
-The left hemisphere has skeletal motor bias, speed optimized, syntax, visual details.
The right has a visceral motor bias, deals with large time domains, prosody, spatial relationships.
-most dramatic example, if one hemisphere is removed in human babies in operation for epilepsy, they show a roughly normal range of functions, although normally these functions segregate into separate hemisphere.
-rich vs. impoverished environments,
- maturation of frontal lobes continuing through puberty (social role learning).
Part III OUR SOCIETY OF MIND.
So, what do we end up with.
A message of this section could be that we should look at our brains as embodied modular action machines designed for passing on our genes. And, we should consider our self conscious awareness only that small fraction of what is going on between our ears that has proven to be useful in guiding actions to the end of making copies of ourselves.
-examples of modularity that have received a lot of attention,
IIIa. 19 th century Verbal language, broca and wernickes areas. Modularity of language suggested by Williams syndrome. Now categories of knowledge handling revealed by different kinds of brain damage, people, animals, tools, from front to middle to rear of temporal lobe.
IIIb. Visual system summary, info from lesions (achromatopsia, akinetopsia), imaging (waterfall illusion) parallel processing up through what, where pathways.
IIIc. Another example of modularity comes in considering dissociation and linkages of thinking and emotional brain. Ledoux, emotional pathways faster.
IIId. Dorsal stream, ventral stream of info.
Where does all this leave us, in trying to think about consciousness and the narrative "I" ? Our natural inclination is to think that our brains see the world as "we" do, that they chunk concepts and perceptions according to the linguistic conventions we use. That there is a little "I' in there looking out at the world.
-But, the components of our experience and percepts are all over the place in our brain, there is no one place where it all comes together.
-What there appears to be in our heads, is a martian, very removed from the viewscreen of our consciousness awareness which is one of its products.
Our brains are survival machines whose sophisticated perceptual and motor modules were shaped by evolution long before the recent add-on of linguistic abilities.
The awareness we try to explain with these abilities is most likely just that small fraction of our total brain/body activities that has proven useful for survival and reproduction.
There would be no point in our consciously attending to the vast number of subterranean activities that massage and process of perception and action or, for example, in being aware that our knowledge of animals, persons, and tools is stored in different parts of our temporal lobes.
What we get from our brains is, to quote from Andy Clark's book, `Being There' is "rather like what a driver gets from an electronic dashboard display: information pertaining those few inner and outer parameters to which the gross activity of the agent can make a useful difference."
Our linguistic habits for chunking reality bear no deep resemblance to the parallel and distributed brain mechanisms used in information storage and retrieval.
-Our main hope is that through new techniques such as more sophisticating monitoring of brain activity we can obtain better insight into the relationship between the local environment, brain activity, and the patchwork construction of our sense of self - between our "I" and the "Martian" in our heads.
-We have to accept for the present the somewhat jarring idea that the "I" inside our heads is a virtual "I" constructed anew in each moment from a cacophony of interaction between brain, body, and world.
So, having mentioned some ideas about evolution, development, modularity, what has this talk been about, punch lines are always the hardest things for me, I would like to send you off with some grand glorious simple ideas,
What more realistically happens is that we add to our list of the variety descriptions given by blind men groping the elephant, trying to triangulate on understanding what is between the ears.
I could worry that I've left you with something like the proverbial Chinese meal that doesn't stick to your ribs. There is no "So! This is how it works!" We have bits and pieces waiting to be assembled into a whole.
Many of us choose to take it as an article of faith that it will someday be possible to do this, others think not. We do have some models for our consciousness that seem worth further pursuit and testing.
So, a summary is that: -Our evolutionary history has given us the "instinct to acquire an art" (using Darwin's phrase) w.r.t. to language, and a natural physics, biology and psychology.
-Our developmental history fits our wiring to the world that is really out there.
-Our modular mind constructions lets us be aware of only that small fraction of what is going on in our heads that has proven useful in insuring our survival.
- Our evolution proceeds now at a theoretic level, the level of cultural symbols, using bodies that evolved for conditions of the paleolithic, bodies whose genetic evolution largely halted more than 10,000 years ago. We are still stuck with emotional psychological repertoires that are more appropriate to those times than to the present.