EVOLVING MIND
This lectures touches on the following:
I. How evolution works (some key topics in ch 2 of text, Biology of Mind.)
II. Animal minds: monkey, apes, hominids (see chapter 5)
III. Hominid transitions, origins of language. (see chapter 6)
IV. Evolutionary psychology
V. Evolution of behaviors, customs, ideas
I. How evolution works
There is an implicit assumption underlying much of the material in this course: that the theory of biological evolution, essentially as outlined by Charles Darwin, has to be the cornerstone of any historical account of how we came to be the way we are.
This is a direct challenge to the creation myths of virtually all religious traditions.
It strains credulity to think that the rich natural world could have been created by anything other than a grand designer.
Charles Darwin's central insight was that a very simple mechanism can, in principle, account for the evolution and diversity of all living things.
The idea is an extremely simple one:
Complex things, whether they are DNA molecules, single cells or complex animals, persist through time by reproducing themselves and in doing so make occasional variations or errors that produce slightly different forms. A very tiny fraction of these different forms prove to be better adapted to their environment, as in avoiding predators or making better use of their resources, so that they are slightly more successful in generating copies of themselves. These more successful forms soon come to dominate the population and are now poised for further adaptation.
The term "Darwin Machine" is sometimes used to describe this process of replication with variation, testing, and emergence of better adapted forms.
How could this explain something as elegant and complicated as the image forming eye, doesn't there have to be a designer? Actually, it has been shown that complex eyes have been invented independently by different animal groups during evolution, arising by a series of small changes as shown in this figure from chapter 2 of the text:
So, what we have is a structure with an obvious purpose, yet fashioned by impersonal forces.
Darwin Machines act over millennia to milliseconds:
We can apply the Darwin Machine idea to offer explanations not only for events on an evolutionary or geological time scale, but also on the shorter time scales of organismal development and moment to moment behaviors.
The field of evolutionary studies is full of controversy
Which is most important, adaptation, lineage, accident?
Why do people has sex? Because their lineage does... (regardless of whether it had adaptive significance when discovered by yeast and worms)
Why are the deeper structures in our brain sometimes referred to as our ''reptilian brain'? because accident + adaptation in the first terrestrial vertebrates made it, we are in that lineage, stuck with it, even though it has been moulded and tuned by more recent adaptive changes.
The idea of chance and lineage are shown by the following slide:
The branches of the single lineage shown here persist and branch further through time if they are not extinguished by accident or disappearance of their ecological niche.
There are multiple lineages changes through time:
So that one sees similar specializations of fish, aquatic birds, and aquatic mammals that enhance their movement through water, all invented independently in their separate lineages.
SLIDE FROM STIMULUS RESPONSE TO HOLDING OR REPRESENTATION
Where might we say that minds appeared in evolution?
Initially stimulus = response, as in chemotaxis, but as animals became increasingly sophisticated at attuning their behavior to the environmental situation the sensory side and the response side of the process must have become partially decoupled.
A central site evolved where representation - in the form of action
patterns - were held back before they were put into effect (you can suppress the urge to scratch).
So, not going to do story of how invertebrate, then vertebrate brains evolved and became more complicated but want to jump ahead to pause briefly at appearance of mammals, us, and what is distinctive about their brains.
This slide is one of more popularized fanciful renditions of the components of the mammalian brain. Fun, but anatomically completely inaccurate.
There is a core reptilian brainstem, reticular formation, striate cortex, basic survival behaviors, the four f's (fighting, feeding, fleeing, fornicating), visual tracking, swift responses, heartbeat,
These portions of our brain make up the majority of the reptile brain.
The limbic system is the major cortical part of primitive mammalian brains (rat, shrew)
This old mammalian brain is a center of motives and emotions capable of responding to present information in the light of memories of past information, originally associated with sense of smell, central in orientation towards offspring that distinguishes mammals from most reptiles. We tend to forget that the behaviors of nursing defending, and rearing immature adults were novel inventions in social evolution.
The neocortex of higher mammals is distinguished by its developmental plasticity, is seat of `higher' faculties....
SLIDE
Now, I want to move on to topic II:
II. Animal minds: monkeys, apes, hominids
I'm taking you through all of these, through the stage of mythic intelligence and language, but stopping short of theoretic intelligence, covered in the last chapter of the book, which was born of the use of external information storage tools like writing on clay tablets, or computers.
-Many animals in addition to primates, especially birds, excel at situational analysis and recall (such as remembering food locations, or predator locations), but there is no hint that they can re-present a situation to reflect on it, either individually or collectively.
-Some of the most complete studies have focused on East African vervet monkeys, not as advanced as Chimps. These monkeys show complex social interactions, classify relationships into types, and also classify sounds according to the objects and events they denote (leopard alarm, snake alarm, eagle alarm, each associated with specific behaviors).
-They have a laser beam sort of intelligence focused to a very narrow sphere. There is no evidence that monkeys attribute mental states to other monkeys. They are skilled observers of each other's behavior, but can't be said to analyze the motives underlying behaviors.
-The monkeys make subtle and penetrating discrimination in social matters, yet don't seem to transfer this capacity to other matters.
-They do not seem to have knowledge of their knowledge, in the sense of being aware of their own states of mind and using this awareness to explain or predict the behavior of either themselves or others.
The great apes - selves and others.
The chimpanzees and other great apes mark a great jump in cognitive abilities. Chimpanzees are socially the most advanced of the non-human primates, and have greater than 98% genetic similarity to us. This is more similar than red-eyed and white-eyed vireos are to each other.
- The chimp life cycle starts with a long period of socialization, and loose bonds are maintained between females and their adult offspring. Societies of thirty to eighty individuals occupy a persistent and defined home range over a period of years. Males cooperate during hunting and sharing of meat in a way that is unique in non-human primates.
- Genocide has been documented, one troop of chimps wiping out another in a slow and systematic way. We don't know whether this is a precursor or a separate invention of the same behavior shown by humans. This chimpanzee behavior at least raises the point that one rationale for human group living may have been defense against other human groups.
-Taken from this angle the traditional idea of "man the hunter" might be valid, but with we ourselves being the prey as well as the predator that made group living necessary.
-Chimps have highly developed manual skills, can solve problems, can use natural tools and have elementary toolmaking ability. Groups of chimps geographically isolated from each other develop different tools and grooming rituals, and pass these on culturally, through teaching and imitation.
-Their ability to look ahead and plan appears to be very limited. No chimp spends an evening going around and tearing off a tidy supply of a dozen probes for fishing for termites the next day.
It is interesting that species other than ourselves haven't come up with a faculty as useful as foresight. It appears to be correlated with the enlargement of the frontal lobes which is distinctive to our hominid brains.
-Groups of chimps show political and moral behaviors that are -strikingly similar to our own. They follow prescriptive social rules and anticipate punishment for their infraction. Rules of reciprocity concern giving, trading, and revenge, along with moralistic aggression against violators.
-They have culture, difference kinds of tool making using twigs or leaves passed down by geographically separate groups.
- We can also recognize analogs of our entire range of human emotions as individuals move between moods of being happy, sad, angry, lonely, tired, embarrassed, etc.
Chimps, orangutans, and human infants at about 18 months of age are unique among the primates in their reaction to mirrors. Monkeys and other vertebrates, upon encountering a mirror image of themselves, never move beyond treating the image as another member of the species and frequently make threatening displays. Now, actually it turns out that Dolphins, which have very large brains, can do this also, and that is a remarkable apparent case of convergent evolution, a sense of self having been independently invented in their evolutionary line and in ours. This really is interesting, and why the paper assigned (I think?) is on this topic.
Chimps who first look into a mirror act as though they were encountering another chimp, but they soon begin to perform simple repetitive movements, like swaying from side to side, while watching their images. Perhaps they are learning that they can control the movement of the `other' chimp.
-They then appear to grasp the equivalence between the mirror image and themselves and start to explore body parts such as the genitalia which they can't ordinarily see.
-If a spot of dye that can't be smelled or felt is placed on a chimp's eyebrow ridge during anesthesia, it will be noticed when the animal first encounters a mirror after waking.
More telling, the chimp will touch the dyed area and then smell and look at the fingers that have contacted the mark, suggesting self recognition - a sense of self.
-Although chimps show behaviors more consistent with having a sense of self than monkeys and less complex vertebrates, there is debate on whether they can perform a further operation characteristic of humans: to appreciate others as also having selves to which beliefs can be ascribed.
So, how smart of chimps? we know they can't do this:
but....
Do chimps, like humans, have a theory of mind (TOM), do they attribute minds or motivations to other chimps ?
There are many experiments on this question, most of them negative, but let me tell you about one, done in Tomasello's lab at Max Planck in Leipzig.... they used a natural situation involving food and hierarchy as being most likely to show evidence for TOM.
They played with the rules for who eats first in groups of foraging chimps.
Condition One...
Three opaque cages in a row, chimp (open circles) in first and third, two pieces of food in the middle cage.
Doors from outer to middle cages opened just enough that each chimp can peek at food and see other chimp eyeing it too.
Open door fully, only dominant chimps takes food, as in the wild.
Condition 2.....
Barrier so that dominant chimp could see only one piece of food, but subordinate could see both, and also that dominant couldn't see one. Subordinate took piece of food, suggesting that it knew the dominant was unaware of this food's existence.
Condition 3, replace dominant with chimp even lower on the hierarchy, the newly dominant chimp goes first after the food both chimps can see, getting the potentially more contested item first, and then retrieves the second. Thus the chimps response is depending on its follow's identity and what is can see, suggesting an understanding of another's visual perspective, or seeing is believing.
So, maybe knowledge of conspecifics desire for food is the first stirrings of mind reading, having a theory of mind. Rumbaugh claims that chimps can use a keyboard to tell human keepers where to find hidden objects.
Another way to obtain clues on the origins of our modern human intelligence is to try to note differences in the structure and wiring of monkey, ape and human brains, developmental differences.....
Chimpanzee Brain
Human Brain
Primates have larger frontal cortices than other mammals, and the prefrontal cortex contains a unique layer of small granular cells.
The most striking brain size increase in the monkey, ape, and hominid transition is in the prefrontal cortex, which occupies ~24% of the cerebral mantle in humans compared with ~14% in the great apes.
Unique changes in magnocelluar pathway in human vs. ape visual system, one clear cortical change noted (Preuss, Kaas)
PET imaging suggests that the left medial frontal lobe is an important locus of theory of mind tasks..
It is also the location of foresight and planning mechanisms that we know to be absent in the apes.
Expansion of the cerebellar cortex in humans is also larger than an extrapolation from primate trends would predict.
A phylogenetically newer part of the cerebellar dentate nucleus that projects to the frontal lobes may be correlated with distinctively human language and cognition.
Now I want to move on to transitions distinctive to hominid intelligence...., reminding you where I am in the lecture topics:
I. How evolution works (some key topics in ch 2 of text, Biology of Mind.)
II. Animal minds: monkey, apes, hominids (see chapter 5)
III. Hominid transitions, origins of language. (see chapter 6)
IV. Evolutionary psychology
V. Evolution of behaviors, customs, ideas
III. Hominid transitions, origins of language
III. Hominid transitions, origins of language.
And, reminding you of suggested stages in the evolution of Hominid minds that we are discussing, having arrived at mimetic intelligence.
Mimetic intelligence - Homo erectus(?)
At the time of the appearance of Homo erectus, ~2mya, major changes were under way.
- more complex facial musculature suggests a richer range of emotional expression and communication
-Changes in the skull and jaw permitted generation of more varied sounds. H. erectus had a larger brain, made more elaborate tools, used fire, had seasonal base camps, and spread out of Africa over Eurasia. Its culture mediated the transition from ape to human.
The word "mimetic" can be used to describe the intelligence of hominids at this stage of evolution and suggests that it remains embedded in the modern human mind. His idea is that this intelligence is similar to that seen in prelinguistic children, illiterate deaf-mutes, and patients seen in a clinical setting who have lost language but retained social skills and communicate by mime. Mimetic intelligence is the kind of cognition needed to learn music, crafts, and sports---largely by imitation, without language. This stage of archaic hominid cognition would resemble the extra-linguistic features of the modern mind.
This kind of intelligence is used in games such as charades and is at the center of arts such as pantomime, ritual dance, or visual tableaux. A central feature is the modeling of social structure. Human infants play role playing games, chimps do not.
Mimetic intelligence would take the episodic present centered fragments characteristic of the episodic intelligence of apes and connect them into linear sequences or repertoires.
-Mimetic intelligence underlies our body language, the nonverbal communication that is signaled by kinetic motions, the kinesic communication, of our faces or limbs. This usually has emotional significance, as when we open up our faces to communicate affection, or contract them if we are rejecting someone.
-Different parts of our bodies, different movement patterns, are essentially organs of social behavior. Social status is regulated by confidence, age, size, and sex (e.g. Is your chest puffed up or collapsed? Is your pelvis thrust forward or pulled back?).
-You are aware of parallel channels of communication from your own experience, especially when verbal and nonverbal messages conflict. (try exercise in book).
-We are programmed by our kinesic context. Are you aware in yourself of the moments when you are imitating the expression on a face you are looking at? This is a universal human tendency. Synchronization of mood is crucial to smooth interaction, and involves linking and orchestration of physical movements. Notice, as you are being a sympathetic listener to someone else, what happens if you suddenly stop the subtle motions of your body or face whose rhythm is matching theirs. We all tend to seek input, and the company of others, that confirms either our current mood or the mood we have a disposition to be in.
-Mood are like viruses
Now, I want to move to the next stage based on the invention of language.
Mythic intelligence - archaic H. sapiens
Origins of Language
-To continue building our story of hominid evolution we now need to add language with syntax and grammar to these complex systems of emotional and kinesic communication.
-One very influential hypothesis is that language is an adaptation that developed because it supported the distinctions that need to be made in increasingly complex social organizations.
-I like the hypothesis that the origins of our current spoken language were in gesture of the sort I was just describing as mimetic intelligence, a step up from the simple signals and alarm calls of chimps and monkeys, hand signals like pointing and signalling alarm, or to pause, or related to mime and imitation, with the gestures and evolving sounds to go with them finally becoming syntactic, having subject, verb and object, it may have been fairly recently, 100-200 thousand years ago that speech became the primary means of communication, in telephone calls speech is the sole communication but we still frequently make hand gestures while talking on the telephone.
Co-evolution of Humans and their Tools.
The advent of tools and language caused the circumstances of hominids to be more and more "self made," essentially turning us into artifacts of our own artifacts. (Homo erectus was making sharp stone flakes for cutting meat about 2 million years ago and bifacial stone tools about 1.4 million years ago.) The fundamental mechanism, termed the "Baldwin Effect" after its discoverer, is that new procedures or behaviors that increase reproductive success are followed more slowly by evolved forms that support them. It seems likely that we adapted to new technology (fire and tools) both physically and psychologically. Thus cooking and processing food removed the need for massive jaws and allowed us to spread to colder parts of the world. Boats allowed migration to distant lands and islands.
How did language rise, get passed on and become one our most important tool? Crucial step, somewhere back in time, was invention of symbols. Sounds that had referenced specific objects began to reference each other.
Evolution of the anatomy of vocalization structures catching up with 'miracle' invention of symbols, provides a good example of the Baldwin effect I was just mentioning. And the brain might then also catch up if a change is invented or just happens (such as duplication of a brain part) and then a use is made of it. i.e. Duplication or enlargement of mouth area of primary motor cortex became Broca's area.
Evolution of Brain Structures Supporting Language
Hominid language is a distinctive feature of the cerebral cortex, while the vocal calls of primates and other animals are controlled by older neural structures in the brain stem and limbic system that generate emotional behaviors. These older structures also control human vocalizations other than language, like laughing, sobbing, and shouting in surprise or pain.
-What we are able to observe in modern monkey brains are areas, presumably present in our common ancestor, that appear to be homologs of the Broca's and Wernicke's areas in humans that are involved in the generation and comprehension of language. The Broca's homolog is involved in movements of the face, mouth, tongue, and larynx, whereas the Wernicke's homolog deals with sound sequences and vocal calls. As is mentioned in Chapter 4, cranial endocasts of H. habilis fossil skulls indicate enlargement of these regions, and some think that the neural preconditions for language are first met in this species.
-The Emergence of Modern Humans
What were hominids doing during these mimetic and linguistic transitions discussed above? We have evidence for several waves of migration out of Africa to the Eurasian continent over the past one to two million years. Archaic humans were firmly established in the Far East between one and two million years ago and in Europe no later than seven hundred thousand years ago.
-Compelling genetic evidence now suggests that all modern humans derive from a small group of common ancestors that lived in Africa between one and three hundred thousand years ago.
Radiation of these successful humans, who displaced erectus and others.
The Origins of Mythic Intelligence
What we're seeing during all these migrations is the emergence of an intelligence made possible by language.
The mind-tool of words permitted the evolution of language, ideas, and the birth of a new kind of culture. Donald suggests that just as mimetic cognition collected episodic event perception into more extended and instructive patterns, the next transition to an intelligence he terms "mythic" collected the scattered repertoires of mimetic culture under the governance of integrative myth---a story of how things are.
-Cultural myths that bind us together. We only feel vestiges of this today, as when we are overcome by powerful public emotions such as patriotism or pride, during song or chanting, the powerful feeling during times of crisis or unity, as during the horrific terrorism events at the world trade center and pentagon.
There is debate over whether language as we know it appeared slowly or suddenly, there clearly was an explosion of mythical art and innovative tool making starting 50 thousand years ago
It is a curious fact that while different groups of humans had spread over virtually all of the globe by 10,000 years ago, their development from bands (containing dozens of individuals) through tribes (containing hundreds) and chiefdoms (thousands) to states (many thousands) was very different in different regions.
The relatively more rapid development of Eurasian, and particularly western Eurasian, societies over the past several thousand years led to social structures and technologies that permitted them to subjugate most of the rest of the world by the end of the 19th century.
Some have invoked racial (i.e. genetic) differences to explain by Europeans were conquering Africans in the 19th century, rather than vice versa.
This really is complete nonsense, because there is vastly more genetic variation between individuals in one racial group than there is between different racial groups.
A much more plausible explanation for why some racial groups appear to have skimmed the cream of the world's wealth and resources is that fundamental differences in geography have made some regions of the world much more favorable for the development of societies ultimately able to support large armies with weapons based on metal working technology.
Jared Diamond points out that the Eurasian land mass has provided a much larger number of plant and animal species amenable to domestication than other areas of the world. The fact that much of this land mass is at the same latitude has permitted travel and a rapid diffusion of new plant and animal technologies that was not possible elsewhere.
Food surpluses allowed the development of states with bureaucratic and military castes, along with sufficient resources to also support development of military technologies.
Further, a consequence of the high population densities of the large cities that rose with the formation of states was that diseases spread much more easily, resulting in the rapid evolution of disease resistance in urban societies.
Thus when Europeans spread to other regions of the globe, smallpox, measles, influenza, typhus, and other infectious diseases played as decisive a role as guns in decimating local populations.
Now, back to our road map, and the next topic, evolutionary psychology
IV. Evolutionary Psychology - the Search for a Universal Mind
The newly emerging field of evolutionary psychology claims to describe and explain human behavior in a fundamentally new way. ---it postulates a complex array of behavioral modules evolved as adaptations to our Paleolithic ancestral environment, modules that are shared by all modern humans.
Some core ideas in evolutionary theory suggest reasons why social modules of mind would have been a plausible evolutionary adaptation for humans.
A starting point was the realization that males and females face different situations in trying to pass their genes on to their offspring. It is the case for many animals, including humans, that males can reproduce hundreds of times a year, but females can reproduce only once.
Thus for a woman there is little (genetic) point in mating with multiple partners, but each new partner of a man offers him a chance to get more genes into the next generation.
Women's reproduction is best served by their being selective about sexual partners, judging fitness and commitment, the potential of the male to contribute to or invest in the offspring. They must sacrifice much more for reproduction than men do.
Sexual selection works in two ways: Males evolve to compete for scarce female eggs while females evolve to compete for scarce male investment. The idea is that in many species there is an evolutionary arms race, with natural selection favoring male brains that are good at deceiving females about their future devotion, and female brains that are good at spotting deception. (One might call this the "sweet-talking" theory of evolution.)
These arguments go on to show how sacrificing for kin or for group actually helps pass on your own genes. How reciprocal altruism, essentially the golden rule might do the same. Check the text on these arguments.
-a debate centers on how these evolutionarily selected behavioral modules are transmitted....there is a strong presumption by many evolutionary psychologists that strong genetic determinants, genes that end up rather directly controlling behavior are involved, but student of developmental biology or human development tend to favor transmission between generations by learning cultural rules from caretakers and peers.
-I'm just going to be efficient here and cut to the bottom line, to say that given the extraordinary plasticity of human brain development, which I'm going to talk about in the next lecture, and crucial and indispensable role of caretaker and peer training in cultural transmission of behaviors that have the same reliability as genetic transmission, the strongly genetic model is dead wrong.
-There surely are some distinctive human genetic instructions that make it possible for us, for example, to learn language, but these genes nudge very fundamental things like nerve conduction velocities, and number of circuits, and cortical columns, etc.
This apparently scientific system of thought is not in fact scientific, but depends at its core upon question-begging, circular reasoning, and unsubstantiated speculation about an evolutionary past which is permanently inaccessible to empirical research. Evolutionary psychology, Feguson concludes, is a modern religion, a religion that exchanges human complexity for the illusion of understanding.
-The fact that a behavior is universal does not imply some sort of very direct link between a gene or genes and that behavior. All that is required of the genetic structures is that they allow the development of modules of behavior that form as humans grow their brains in a social dialog with other humans as well as their natural physical environment.
The fact that the result may be a module of social behavior present in all humans may attest to the uniformity of the developmental environment of those humans, not to genes directly establishing that behavior.
Just as feral children raised by animals in the wild are unable to develop language, so they also presumably fail to develop the array of social modules of behavior suggested by the evolutionary psychologists.
-Transmission of learned behaviors is found throughout the animal kingdom, in birds, in mammals, particularly.
And, that brings me to the last topic in our list: the evolution of behaviors, and of ideas:
V. Evolution of behaviors, customs, ideas
More specifically.... these topics:
-Ideas and customs, in addition to our genes, can act as units of information transfer that regulate behavior and are passed from one generation to the next. In humans and other animals, learned behaviors can be passed on as reliably and reproducibly as if the information were in the chromosomes.
-Students of animal behavior use the term phenotypic cloning to describe the process by which parents can so firmly impress behaviors on their offspring that the behaviors (phenotypes) seem to be inherited. (In spite of what we like to think, we all act amazingly like our parents as we grow older.)
A core point is the argument that differences in behavioral styles between one family line and another provide a context for natural selection. The behaviors that work best get passed on because of differential reproductive success, and less adaptive behaviors are lost from the "phenotypic pool," analogous to the gene pool of genetics.
This mechanism acts also at the level of cultures of humans and animals, and in this context it is sometimes called group selection. Over longer periods of time, genetic changes in individuals that facilitate the adaptive behaviors adopted by a group might then be selected for. This is the Baldwin effect mentioned above.
-Human cultural groups are adaptive responses, just as are birds' feathers and mammals' fur. They are vehicles of selection and have the effect of reducing the importance of fitness differences between individuals within the group. Groups of humans organize and defend themselves as if they were individual organisms, with homeostatic mechanisms and defense strategies. They have a sense of "I," with childish and adult components.
-To describe the propagation of cultural ideas the biologist Richard Dawkins has used a genetic analogy and coined the term meme (rhymes with cream). The term meme refers to a unit of cultural information that replicates itself reliably. The meme is a replicator, the cultural equivalent of the gene. It might be a ritual of greeting, or of competing, or a piece of music.
-This is an incredibly important new force of biological evolution, compare time scale with earlier ones.....
SLIDE: Media of evolution
Genetic evolution - thousands of generations
Phenotypic plasticity - single generation,
Memetic evolution - days
Neuroscientific engineering - single generation
-I've attempted a summary of how these various kinds of evolution fit together - selection for different genes, developmental strategies, behaviors, ideas, cultures, etc. -
The crank of the Darwin machine turns at many different level of organization, from genes, all the way up to cultures competing with each other.
- Changes occur more rapidly at higher (behavioral) than at lower (genetic) levels.
-An adaptive change at a higher level that acts as a long term solution to a problem can slowly be enhanced by genetic changes that facilitate that adaptation.
So, to recap this lecture:
We talked about
I. How evolution works
II. Animal minds: monkeys, apes, hominids
III. Hominid transitions, mimetics intelligence, origins of language, mythic intelligence
IV. Evolutionary psychology
V. Evolution of behaviors, customs, ideas, media of evolution.
Plasticity, adaptability, changeability become more and more important, and this is the topic we engage in the next lecture, how each of our brains grows, wires itself, generates a self in an astoundingly flexible way.
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