Outline and Notes

This posting collects all the outline and notes postings in one place

Chapter	Outline	Notes
1: Big Brains, Bigger Brains	Outline	Notes
2: The Mind in the Machine	Outline	Notes
3: Genes Build Brains	Outline	Notes
4: Brains Arrive	Outline	Notes
5: The Brains of Mammals	Outline	Notes
6: From Olfaction to Cognition	Outline	Notes
7: The Thinking Brain	Outline	Notes
8: The Tools of Thought	Outline	Notes
9: From Brain Differences to Individual Differences	Outline	Notes
10: What's in a Species?	Outline	Notes
11: The Origins of Big Brains	Outline	Notes
12: Giant Brains	Outline	Notes
13: All But Human	Outline	Notes
14: More than Human	Outline	Notes

Notes on Chapter 14: More than Human

This chapter was largely about speculation: what cognitive abilities might Boskops have had?  Why did the Boskops die out?  What might the next steps in human intelligence be?

In the section "Brain and Superbrain" where the authors talk about why Boskops might have died out they raise the point again about how being super-intelligent is not that useful if you don't have a society to pass your insights on to.  While the average high school student may not be the equal of an Einstein in math, they do start out with knowledge gleaned from several thousand years of studying mathematics.

"The Final Path to Humans" points out that genetic control over brain structure is likely to be rather imprecise hence trying to engineer a human with superior cognitive abilities through genetics alone is liable to be very difficult.

The section, "Inconsistent Brain," talks about how Dmitry Belyaev domesticated foxes.  The reason I found this interesting it shows how simple breeding style genetics can result in behavioral changes.  Further investigation of exactly what produced a friendlier fox - was it a change in brain structure, hormones, something else - would be a fascinating study.

Chapter 14: More than Human

• Brain and Superbrain
• What abilities might a larger brain yield?
• Long paths: "Think it through"
• Being able to more fully explore the ramifications of a decision.
• Branching paths: "The continuity of self"
• Being able to recall the way that you were
• Example: when you were younger
• Stations at the ends of paths: "Phaedrus' knfie"
• Able to make very fine distinctions.
• (Why did the Boskops die out)
• Maybe they didn't want to spread like H. Sapiens
• Maybe they never reached a "critical population mass" where intelligence could have been more useful.
• New Paths, New Humans
• Speculation on how structural changes could have been triggered by minor gene changes.
• The Final Path to Humans
• Early mammals probably had brains that were focused on olfaction and audition.
• When mammals moved out of nocturnal niches, they had more brain development in the visual regions.
• Human beings are strongly auditory
• Human infants are more auditory than visual
• Audition would be useful to a language oriented species
• Neanderthals may have been more visual (larger anterior cortex)
• Genetic control of brain growth is very imprecise
• Stadium analogy
• Inconstant Brain
• Domestication of foxes
• Dmitry K. Belyaev's experiment in the 1950's
• Bred foxes for docility
• 30 to 35 generations
• Bred a group of foxes that were friendly to humans
• How were they different
• Physical
• Floppy ears
• Rolled up tail
• Coats of more than one color
• Mental/Chemical
• Higher levels of neurotransmitters such as serotonin
• Brain - uknown
• Rat breeding in the 1930's
• Bred for maze running.
• Could achieve the same results with normal rats by putting them in a maze for a few weeks.
• Next Steps
• Asperger's high functioning group
• If they moved to an island
• Transhumanists - directed evolution
• Using drugs that enhance learning abilities
• Resurrect the Boskops --- using their DNA
• Coda
• Boskops may have died out because of infant and mother mortality
• Perhaps they were wiped out by more warlike humans
• Perhaps they still exist and just blend in with the rest of humanity
• Anecdote about Boskop grave

Notes on Chapter 13: All But Human

The big thing I got from this chapter was that there is more to support the notion that most of the differences between human and animal cognitive abilities stem from the size of the human brain as opposed to its quality.

The evidence cited for differences in human vs. animal brains seemed fairly slim by comparison - from a structural standpoint it does not sound like there is a whole lot of differences between human brains and other primates.  The differences in proteins also seems rather small.

One area that is completely ignored is that glia cells - the non-neuronal cells in the brain that perform functions such as immunity, neurotransmitter re-uptake and myelination.  The book The Other Brain: From Dementia to Schizophrenia, How New Discoveries about the Brain Are Revolutionizing Medicine and Science describes how these other cells, that outnumber neurons in the brain by more than 3 to 1, appear to do much more than simply provide support to neurons.  It would be interesting to learn whether human brains differ significantly from other mammals with respect to glial cells instead of focusing exclusively on neurons.

The part at the end of the chapter about Boskops seemed out of place with respect to what the rest of the chapter talked about.  Furthermore, the discussion does not mention Neanderthals, Cro-Magnons or other possible sub-species that might have had a larger brain size than modern humans: the discussion left me thinking that the authors considered Boskops to be another sub-species rather than statistical outliers.

The discussion about Boskops does give a very good reason for decreasing brain size, to whit that a larger brain at birth translates to a more difficult birthing process.  Given how dangerous childbirth is for modern women, a child with a 30% larger head would pose an even greater risk than existing babies.  The loss of a mother is especially bad because it means the loss of an established and valuable member of a society, making a community of large brained individuals even more difficult to support.

Chapter 13: All But Human

• Introduction
• Science is empirical: based on observation.
• It is difficult to "prove" that something is true, instead often times you eliminate alternatives.
• Well known facts can have exception: Newton vs. quantum physics.
• Are human beings intelligent because their brains are different from other animals or because the human brain is larger?
• Differences
• Most of the human brain is the same as other animals
• Cell Types
• Voon Economo neurons - only occur in humans gorillas chimps and bonobos.
• Occur in areas that are active during social interaction.
• Local Circuits
• Broca's and Wernicke's areas.
• "Double-wide" brain cells.
• Connectivity
• Our brains appear to form synapses more readily than other animals.
• Protein thrombospondin.
• Neurons have longer dendrites and have more synapses than apes.
• Human brain is 3 times the size of a chimp brain, but it does not have 3 times as many neurons.
• Recent Genes
• FOXP2
• 200,000 years old.  
• Appears to be language related.
• Microcephalin 
• 50,000 years old
• Regulates brain size
• ASPM
• 10,000 years old
• Involved with microcephaly - reduced brain size.
• Brain Shape
• Area 10
• Involved in higher brain functions.
• Could be larger than expected.
• Others claim it is the correct size for a 1350cc brain.
• From Quantity to Quality
• Where does language come from?
• Why do humans have it, but no other animal seems to?
• Some theorize that humans have a special language module in the brain.
• Others argue that it is size - human beings have much larger (400%) brains than chimps, etc.
• For the time being, neither argument can be conclusively proven as more likely.
• From Brain Advances to Cognitive Advances
• The gap
• Big brains arrive 100,000 years ago
• Real cultural changes start at roughly 20,000 years ago
• Why the gap?
• Critical mass theory
• A critical population is needed to create and pass on knowledge.
• From Cognition to Language
• Observation is that the cortex is already set up to reason in terms of grammars.
• Then the existing structures can be easily used to deal with languages.
• Rather than trying to create a new structure just to deal with language.
• Learning Curve
• There is a large gulf between human style communication (complex) 
• And animal style communication (relatively simple).
• Theory that as a cortical circuit is lengthened, the grammars it can recognize become more complex.
• From Speaking to Writing
• Written language skills are among the most difficult cognitive skills that humans display.
• Unlike spoken language, reading & writing cannot be expected to manifest spontaneously.
• Lack of evidence of reading & writing could have been because of a lack of population 
• 30,000 years ago Europe had a population of around 5,000.
• Why did the Boskops die out?
• Massive difficulty with childbirth (larger heads).
• Means a smaller population
• Smaller population means no critical mass.
  

Notes on Chapter 12: Giant Brains

Ideally, this chapter explains why the Boskop find was forgotten. In the first couple of sections, the authors talk about how the find was viewed by prominent scientists and how there were multiple finds that corroborated each other.

The section, "How Giant Brains were Forgotten," goes into the Piltdown fraud.  The authors argue that the fraud tainted subsequent finds by British paleontologists and that the Boskop discovery fell victim to this.  A secondary reason for the find being forgotten is the "irresistible fallacy" that human beings are the apex of evolution, that evolution leads inexorably towards intelligence and that therefore no prehistori

Preview

c species could have been more intelligent than humans.

The authors spend the rest of the chapter speculating about how Boskops could have been more intelligent and the nature of intelligence itself.

According to the authors, their intention was not to try and cast the Boskop find as an indication of a separate race.  To quote the above link:  It is not possible to read Big Brain and conclude that the authors believe in any way in this notional “Boskop race”, nor that we have in any way somehow mistakenly adopted decades-old, long-rejected interpretations of these skulls.

The problem I had with this was that I did get the impression  that the authors were trying to argue in favor of the notion that the South African find was indicative of a "Boskop Race."  Whether my impression is unique or not is something that you will have to figure out by reading the book on your own.

Chapter 12: Giant Brains

• Introduction
• Back to the Boskops
• The find was examined by others
• The Man of the Future
• Fitzsimons found 3 more skulls.
• The subsequent finds were more complete than the initial find.
• Boskops were the inspiration for aliens like the "grays"
• All this happend near the time of the Piltdown fraud
• How Giant Brains were Forgotten
• About Piltdown
• 1912
• Gravel pit in the Piltdown region of England.
• Charles Dawson was the "discoverer"
• Dawson took his find to Arthur Smith Woodard
• The Piltdown discovery became very popular in England though doubted in other parts of the world.
• Martin Hinton was apparently the perpetrator of the fraud
• "practice" bones were found in one of his closets
• The fraud created a lasting stain on the reputation of British anthropology
• Inside the Giant Brain
• Speculation on Boskop capabilities
• Boskops had approximately 25% larger brains than modern humans
• Argues for enhanced planning, memory and association abilities.
• Giant Brains and Intelligence
• Nobody knows what effects a larger brain would have on IQ.
• Guesses that 25% larger brain would result in 10-30 points.
• People who were "gifted" (130+) would become genius level (140 to 160).
• People who were genius level (150+) would become superhuman (160 to 180).

Notes on Chapter 11:The Origins of Big Brains

The message I took away from this chapter was that, for an animal to have a big brain in adulthood, it must have a large brain at birth.  During our evolution, human beings have evolved in such a way so as allow for offspring to have a huge brain at birth - even though an adult mountain gorilla may ultimately weigh in at 200kg, a human baby is almost twice the size of that same gorilla at birth!

One question that I had was "why is birth brain size so important?"  That is, why can't the brain of an animal grow massively after birth thereby allowing for a safer and easier birthing process?  I did not see an answer to this in the chapter.

Another point from this chapter was that, according to the authors, the mosaic theory of brain development does not find support in studies that compare the sizes of brains amongst primates.  Specifically, mosaic predicts that brain areas that are more useful should be larger than others.  But instead the brain regions appear to be the same relative sizes in all primates.  Useful brain regions are larger in humans, from an absolute standpoint, because the human brain is larger.

In an interview with Dr. Ginger Campbell on the Brain Science Podcast, Dr. Lynch mentions that a nice aspect to this theory is that it does not require special explanations regarding how evolution selected for intelligence, it just requires that evolution select for large brains.  While part of this can be explained by simply increasing the size of a human being (chimps and gorillas need larger brains than monkeys because their bodies are larger), this does not entirely explain human beings, because we have large brains even when compared to other primates.

Chapter 11: The Origins of our Big Brains

• The History around fossils
• Happened in and around the time of Darwin
• 1887 Discovery of Neanderthals 
• Virchow said the remains where a modern man with rickets
• Haeckel thought they were legit
• Dubois predicted that the "missing link" was in the Dutch East Indies
• Brain size in primates
• Body weight vs. brain weight seems to follow a logarithmic scale
• Except for humans - brain is larger than expected.
• Increase body by a factor of 10 and you get a 10 fold increase in brain size.
• 10^(x * g) where g is a constant
• Very good model for predicting brain or body weight given the other.
• Brain region sizes correlate very closely with other primates
• Gorillas and chimps are smarter than monkeys (communication, tool use).
• Humans have large brains even for a primate
• Brain size in the family of man
• 6 million years ago - start of split towards bipedalism
• 5 million - bipedal vs. non-bipedal are distinct species
• 4 million - Australiopithicus
• 450cc brain
• 2 million - Homo Habilis
• 600cc brain
• First evidence of tool use
• 1.5 to 1.8 million - Homo Erectus
• 800cc brain
• 500,000 - Homo Erectus+
• 1000cc brain
• 100,000 - Neanderthals
• 1500cc brain
• 10% larger than H. Sapiens (~1350cc)
• Mosaic theory vs. concerted
• How intelligence occurred
• Mosaic theory - evolutionary pressure for different brain regions at different times.
• Concerted - no pressure for any one region, just scale up the existing brain.
• Concerted predicts the size of various brain regions, mosaic does not.
• Big Babies
• Discussion is predicated on one accepting the concerted theory.
• Bipedalism
• required for walking erect
• Wider hip size
• Larger babies
• Birth weight determines brain size
• If you have a large brain then you must have larger babies at birth.
• Human - 1350cc brain - 3.3kg
• Gorilla - 500cc brain - 1.6kg
• Chimp - 400cc brain - 1.5kg
• Hip size
• Humans: 20% difference between men and women
• Chimps: 5% difference
• On Intelligence
• Where does all the brain power go?
• Memory
• Anecdote about memory experiment
• 10,000 picutres
• 90% accuracy (have you seen this before).

Notes on Chapter 10: What's in a Species?

The chapter talks about the fact that there are no other species in the same genus (homo) as human beings is rather unusual.  The authors go on to note that during most of the past million years, there were usually only 1 or two species in the genus at any one time.

The authors implicitly ask the question: is this because of how humanity evolved, or because of how human beings have been classified: are we really that different or have some scientists wanted to show that our species is different from the rest of the animal kingdom?

A bit of evidence is given for both cases.  For the notion of adding other species to the same genus there is the observation that the Neanderthal and human genomes indicate more interbreeding than was thought to have occurred before.  What's more, the authors note that the fossil record is relatively scant to base classification on.

On the side of differentiation of species, the observation of large brains, certain teeth and some behavior (notably speech) is mentioned.

Then the authors digress into a discussion of eugenics and some observations about why it is wrong and who supported it in the past (surprisingly, this includes Winston Churchill).  The authors note that even modern humans do not completely understand how the genome works or what all the pieces do, and what's more cannot define what "better" is.

I found the chapter's points to be rather obtuse: writing up this discussion was as useful in trying to understand the message as reading the material.

Chapter 10: What's in a Species?

• Introduction
• It is unusual to have only one species from an evolutionary group
• Times when there are multiple hominid species: 50 to 100 thousand years.
• Total time that hominids have been around: 1 million years.
• Definitions
• The homo genus is controversial
• Some say that Neanderthals, etc. should be in that genus.
• Some say that Boskops were a separate species.
• Fallacies of the notion of race
• Separate gene pools vs. interbreeding populations.
• Not strict categories
• Eugenics programs
• Have occurred throughout history
• Part of the problem is how do you define "better"
• Surprising list of people who have supported such movements
• Winston Churchill - sterilizing the "feeble minded"
• Alexander Graham Bell - sterilizing the congenitally deaf
• George Bernard Shaw - involved in the eugenics movement
• Races Versus Gene Pools
• Genetic variation in a subgroup is just as common as in the entire population
• May be restricted in what can vary.
• The absolute amount of variation is the same.
  

Notes on Chapter 9: From Brain Differences to Individual Differences

The mail takeaway I got from this chapter was that genes are an important aspect of a person's potential, but they only determine about half of the traits a person might have.  The rest are determined by the "environment."  "Environment" in this case can mean things as diverse as diet, training, interaction with microbes, etc.


The authors seemed to be careful to point out the limits of genetics and the problems with trying to define just what a "superior" person is.  Three examples are given of people who can be seen as handicapped in some way, and yet possessing significant advantages in another way.

The authors describe the results of studies using fMRIs and reading skills which indicate a correlation between reading and certain brain configurations.  The problem is that having two related traits does not tell you whether one trait causes the other or if they are both related to some other trait. 
For example: do people with good reading skills cause their brain to be configured a different way, or does having a particular configuration mean that the person is a good reader?  Another possibility could be that people with good reading skills receive abundant dietary essential fatty acids during a key period of growth.

Diffusion Tensor Imaging

According to an article I found, Diffusion Tensor Imaging (DTI) reveals the circuits in the brain that are activated during a given activity.   DTI is another form Magnetic Resonance Imaging (MRI) that tracks the large movements of water molecules.  Since blood is largely water, this sort of scan should show the routes that blood is flowing to and hence show the neural pathways that are being activated.

Contrast this with Functional MRI, which shows where carbohydrates (sugar) is being consumed in the brain.

Chapter 9: From Brain Differences to Individual Differences

• Introduction
• Do genetics predispose individuals to have different abilities
• Examples of people with different brains/abilities
• Les
• Premature, blind, only expected to live a short time
• Incredible memory, natural concert pianist
• Willa
• Williams Syndrome
• Brain is 15% smaller than average
• At 18, roughly the level of a first grader
• Gifted writer
• Kim
• Missing corpu collasum and anterior commissure
• Can perfectly recall anything he has read
• Similar to the "rain man" in terms of difficulties with day to day life.
• Very minor genetic changes resulted in these differences
• What sorts of changes could bring about these changes?
• Brain Paths
• Diffusion Tensor Imaging (DTI) 
• MRI that traces paths through the brain
• May lead to predispositions due to genetic factors
• Genetic control is highly indirect.
• Example with the rat rewiring its brain to repair damage.
• Brain Tracts and Differential Abilities
• Reading ability could be tied to brain wiring
• Nature vs. Nurture
• Genetics control roughly 1/2 of our brain traits.
• Someone who is predisposed to having a trait my still not develop that trait.
• Based on identical twin, fraternal twin and adopted sibling studies.

Notes on Chapter 8: The Tools of Thought

I found this chapter to one of the longer and more difficult to comprehend chapters in the book.  The basic ideas were intriguing, in particular:

• Memories are hierarchical.
• Recognition is a multi-stage, temporal process.
• Brains are naturally amenable to grammar like organization.

A basic concept used throughout the book is that larger brains lead to new abilities, even though the larger brain is just "more of the same" in that a larger brain does not have new or different structures, just larger versions of the same thing.

Thus, if memories are hierarchical, then a larger brain means more categories and deeper hierarchies.  If recognition is multi-stage, then a bigger brain can mean more stages and a finer distinction between otherwise identical items.  If brains and thought uses a grammar like structure, then a larger brain could mean a more elaborate grammar.

I find the notion of the "scavenger hunt" model for memory especially interesting.  While that approach seems especially strange, it does dovetail nicely with the associative nature of the brain: each "step" in a memory is an association.  Each association can be reused in different memories because they have a certain "momentum:" a memory is the sum of what came before plus the next association.

Chapter 8: The Tools of Thought

• Feedback and hierarchies of cortical circuits
• If our brains is the same as a mammal brain, just larger, how does it gain new abilities?
• Feedback Circuits
• The cortex is wired both from sensory systems to something else and from the cortex to the sensory systems.
• Can re-experience sensations without the actual stimulation.
• Can rearrange and examine the steps that are taken.
• Steps of Recognition
1. Initial Activation
• The flower example
• Sensory impression
• Contains more data than the brain can process
2. Learning
• Group different flowers into categories
• Group all flowers into plants
• Generalizing and differentiating
• Generalizing: flowers, plants, commonalities
• Differentiating: what makes a rose different from a daisy
3. Feedback
• Once a category is established, feedback suppresses differences
• Thalamus is involved in suppression
• Effect is that the cortex only sees the common aspects in the first sensation.
• Next sessions, the differences start to arise.
• Thus an instantaneous experience becomes a sequence of experiences.
• Sequences
• In addition to breaking a single sensation into multiple steps as per categories.
• Flower petal example: start with one petal, look for the next.
• Validate a possibility
• What One Brain Area Tells Another Brain Area
• Old tools are relatively crude
• EEG, PET scan, CAT scan
• Includes fMRI
• What's in an Image?
• Description of how fMRI works.
• Putting it Together: From Generalists to Specialists
• Fallacy: the wheels moving the car
• Something else actually turns the wheels
• Controversy over recognition
• Grandmother cells
• Specific cells encode information.
• Distributed
• populations of cooperating neurons represent information
• Memory Construction
• They advocate a hybrid approach between Grandmother cells an a distributed system.
• Distributed in the sense that no one neuron encodes a particular memory
• "Grandmother" like in that neurons do exist that are very highly tuned to a particular type of image
• A sort of "shared grandmother cell" approach.
• Building High-Level Cognition
• Large brains lead to long cortical processing areas.
• Libraries and Labyrinths
• Memories are stored as routes through the brain instead of one location that has all the data.
• Scavenger hunt analogy
• Grammars of the Brain
• The way the brain works is similar to a linguistic grammar
• There are rules that govern what sequences of thoughts are allowable
• Specific pathways store individual memories.
  

Notes on Chapter 7: The Thinking Brain

I found this to be a rather discordant chapter.  It starts by talking about evolution of the brain in terms of size and then switches over to a discussion of how the motor systems work. I think the point that the authors are trying to make is that the association regions got larger so that it would be possible to make more elaborate and detailed plans. 

Another point is that the brain deals with detail hierarchically.  With the pitching example, the planning portion of the brain deals with the high level concepts - use a slider pitch instead of a fastball - and then passes that command onto the next brain system.  That brain system selects the general set of movements required and passes each off to the motor portions.  The motor portions control the muscle movements for each step and cause the actual neural signals to be sent out.

The last part of the chapter portrays a struggle between the higher and lower portions of the brain for control.  The discussion is vaguely related to what came before (higher levels controlling lower levels) but it is portrayed more as a struggle than a cooperating system.  The authors note that the larger the brain is, generally the more control the higher portions of the brain have over the lower portions.

To illustrate the conflict aspect, the authors mention a movie where the conscious and subconscious minds are in what amounts to a pitched battle over control.

Chapter 7: The Thinking Brain

• Introduction
• How did we get big brains?
• Irish Elk analogy 
• Our brain is a scaled up version of a monkey brain
• Question becomes why are we so large?
• Mammal brains scale consistently
• Primate brains scale very predictably
• Extending thinking over time
• Various parts operate in concert
• The pitcher example
• Cortex: select a pitch
• Cortex tells the motor context 
• Motor cortex selects the individual, high level movements
• Motor cortex tells the striatum to perform a lower level movement
• Striatum initiates the individual movements with the body
• This is the basis for higher level planning
• The Cortex Takes Charge
• Larger cortex means more control over the lower portions of the brain and body.

Notes on Chapter 6: From Olfaction to Cognition

I found this to be a challenging chapter because it introduced a large amount of technical material that I was unfamiliar with.  In addition, I found it difficult to follow the discussion of just how one gets from olfaction to cognition - the supposed point of the chapter.

The section "From Cortext to Behavior" had the best discussion of this concept but was by no means clear.  Here is what I came away with:

• Different combinations of brain structures lead to different information about a sensation.
• Thalamo-cortical loop: what the smell means
• Cortex/amygdala: emotions or states that result from the smell, for example, hunger
• Cortex/Hippocampus: ability to recognize the context of the situation.
• Cortex: ability to form a plan such as how to approach the food.

One question that I have is what did other people come away with?  Was it basically similar to this or did they get something else out of it?

The next claim the book makes is that random access/associative regions emerged first, then point to point systems emerged.  The traditional view is the reverse.  How has this theory fared in the years since the book was published?

Chapter 6: From Olfaction to Cognition

• Introduction
• The major brain structures
• Striatum 
• involved with movement
• Stimulating the striatum can cause jerky, twitching movements.
• Prof. Delgado and the bulls
• Amygdala
• Controls the hypothalamus
• Hypothalamus links the neural system to the endocrine system.
• Involved in primitive emotion
• "Terminal Man" anecdote
• Hippocampus
• Memory
• Henry anecdote
• Receiving desk anecdote for memory
  
• Thalamo-cortical loops
• Frontal cortex and the thalmus
• Dorso-medial nucleus (DMN)
• Planning and outcomes
• All the systems act in concert
• From Cortext to behavior
• One sensation can trigger multiple thalamo-coritcal messages
• example: smell something
• thalamo-cortical loop
• what is it that you smelled (food)
• what could happen as a result of smelling (eating)
• olfactory cortex/amygdala - hunger
• cortex/hippocampus
• recognize the setting
• combine with stimuli and past outcomes
• Arrive at a predicted outcome to a course of action
• Neocortex
• Early mammals depended on smell and hearing
• Visual systems lagged behind
• Most brain expansion was dominated by random access/associative structures rather than point to point.
• Traditional view is the reverse: expansion was in point to point systems and then the associative areas formed later.
  

Notes on Chapter 5: Brains of Mammals

This chapter was fairly short but it was also pretty focused on describing how the various mechanisms of the brain work. 

Associative Cortical Circuits
A central concept to the book is the idea that there are two broad categories of sensory processing regions in the brain: point to point and "random access" (I refer to this as associative).  The idea is that, for systems like the motor regions, if one muscle is physically situated near another muscle, then the corresponding brain regions will also be located near each other.

This is not the case for the brain region that processes the olfactory senses.  Instead that region follows what the authors call a "random access" scheme.  In that arrangement, while the primary sensory inputs are point to point, they quickly lose that aspect.  For example, the scent of oranges might be associated with food, or the scent of a mountain lion could be associated with the notion of danger.

I call this arrangement "associative" because it hearkens to the notion that a primary sensation (in this case a smell) is associated with something else. 

Why would being warm blooded help "absorb the cost" for having a large brain?
The authors mention several times that having a large brain is biologically expensive.  One issue is the number of calories consumed by neuronal tissues.  I suppose one reason that being warm blooded might help is that, if the organism is going to be consuming a lot of calories to keep the body at a constant temperature, then the cost of having a large brain would be, proportionally speaking, smaller.

Nevertheless, it seems to me that an organism that needs additional calories to support itself because of a large brain would still be at a disadvantage relative to one that had a smaller brain.

Chapter 5: Brains of Mammals

• Introduction
• Olfactory brain is sheet-like, similar in structure to the cortex.
• Neurons and Networks
• Discussion of how a signal travels down a neuron.
• Olfactory is associative not point to point like vision or touch.
• Description of the olfactory system.
• Learning
• Description of neuron learning
• Once the olfactory system became able to learn, it could be used for anything, not just smell.

Notes on Chapter 4: Brains Arrive

This chapter has a number of points that are central to the book:

• The olfactory system is associative instead of being point to point.
• When brains get larger, they do so disproportionately.
• Big brains are expensive.

The Olfactory Brain Regions are Associative
The important thing about associated vs. point to point is that the authors argue that the foundation for the neocortex  already existed long before primates with their larger brains showed up.  One of the primary abilities of the cortex is its ability to associate anything with anything else - something the olfactory system must be able to do in order to associate a particular smell with some attribute.

This makes for a more "natural" transition from the smaller brains to larger human brains.  Nothing special is required to explain how the cortex becomes associative: it evolved from the olfactory regions.

When Brains Become Larger, they do so Disproportionately
Disproportionate growth in brain areas means that, rather than the motor and sensory parts of the brain increasing at the same rate as the cortex, more expansion can go to the higher brain functions instead of the lower ones.  According to the authors, this trend is already apparent with birds and mammals, whose growth patterns are different from those in fish and reptiles.

Another point about brain evolution is that the proportional sizes of different brain regions are more or less constant for different classes of animals.  That is, the brain regions of a larger animal such as a moose, are proportionally the same size as those of a smaller animal such as a mouse.  Because the moose is bigger, it has a larger brain, but the relative sizes are more or less the same.

Large Brains are Expensive
The authors point out additional costs of big brains later on in the book.  For now, the point about the metabolic cost is highlighted.  In looking at the way that humans will keep dairy animals and noting that this gives them access to an extra 100 calories or so, it is clear that having a larger brain that confers no corresponding advantage is serious drawback.

And just to make the cost more onerous, 50% of calories for nervous tissue must come from carbohydrates.  Normally, calories come from starches and sugars, so this is not an issue, but under starvation conditions, these calories come at the expense of cannibalizing lean body tissues.

Chapter 4: Brains Arrive

• Introduction
• In early animals, the nervous system is mostly about processing senses and controlling movement.
• As brains increase in size, disproportionate amount of the new space go to internal processing.
• First Brains
• Point to point, sensory systems.
• The striatum is an organizer for signals
• Motor outputs
• The different motor regions are very different from each other.
• The olfactory part of the brain is different from the other sensory systems
• Associative instead of point to point.
• Brain Expansion
• The size of the brain relative to the size of the animal is constant in fish and reptiles.
• But not for mammals or birds
• Protomammals develop better hearing and olfaction
• Birds develop better vision
• Brain size in both jumps 300%
• Note that a larger brain can be a disadvantage
• Higher metabolic cost
• The protomammals were evolving "wildly" because of intense competition with the dinosaurs.

Notes on Chapter 3: Genes Build Brains

Compressed Genomes

The description of how genes work, in particular that they do not code to all possible variations, only ones that fit a particular pattern, is appealing to me because it makes intuitive sense.  What is the point of coding to variations that are not viable?

Reasoning like this is dangerously close to asserting a "design" in the human genome instead of assuming that variation is random, something that I think of as a pitfall.  That being said, it does make a lot of sense and seems advantageous for an animal because it would take less energy to replicate the genome.  Furthermore, mutations are less liable to be catastrophic because most of the variation occurs in areas that do not have that effect on an organism.

Non-Genetic Variation

The idea that there is a limit to how much control genes have on brain makeup is also attractive because it seems to fit the evidence.  There are cases where a person could get Alzheimer's and their identical twin does not.  This sort of thing is hard to explain if all aspects of the brain are genetically controlled.

Furthermore, there is precedent for non-genetic control of different aspects of the organism.  For example, identical twins usually have different fingerprints because the patterns on fingers vary due to blood flow in the womb instead of being completely determined by genes.

Chapter 3: Genes Build Brains

• Introduction
• Evolution is random, not directed.
• Humans are what has survived, not the pinnacle.
• Other results were possible, we just happened to survive.
• How Much Variation can Occur?
• Basic Genetics
• Basic unit of a strand of DNA is a base pair.
• A group of 3 adjacent base pairs form a codon.
• Each codon maps to one of 20 amino acids.
• A string of codons (with a start and stop codon) make up a gene.
• A gene codes to a protein.
• Most of the DNA occurs outside genes (introns)
• There are around 25,000 genes in the human genome.
• Odd factoid
• Human and chimpanzee genomes differ by only about 3%.
• But one human being's genome may differ from another's by up to 12%.
• Which genes are varying is more important than the number of genes.
• Blueprint Systems
• Compares computer code to genes.
• Computer code is very brittle, i.e. changing a bit in a program could seriously impair the program
• Genes are more resilient
• Bundling Genes
• Variation is random, but it is constrained
• Genes are a sort of constrained language
• Makes them more resilient but also limits them
• Genes only code to viable combinations, not all combinations.
• Large Brains are Expensive
• Nervous tissue requires twice as many calories as others
• Note that 50% of that must come from carbohydrates
• Requires large animal at birth
• Increases risk to the mother
• If it is expensive, why do humans have them?
• Common theory is that intelligence is strongly selected for.
• Theory in this book
• Larger brain was an "accident"
• Larger brain had additional utility
• Then the species adapted to having larger and larger brains.

Notes on Chapter 2: Mind in the Machine

This chapter introduces the key concept of point to point vs. associative brain systems.  Associative systems are important to the rest of the book because they form the basis of what the authors claim is the foundation to intelligence - the ability to associate two otherwise unrelated pieces of information.

The sensory system that serves as the primary example of this--smell--is also key because the authors will argue that this sense was very important to early mammals.

The part of the chapter that compares and contrasts computers with human brains highlights the ways that brains and computers differ.

• A brain always comes with an associated body.  A computer has a case, peripherals, etc. but it cannot really do anything on its own.  
• A brain will learn from experience and modify its behaviors.  Generally speaking, a computer will not learn from experience nor will it spontaneously change its behavior.
• Changing the size of the brain results in new and different abilities.  Making a computer faster or giving it more memory generally does not change its capabilities.

I don't entirely buy into the argument that increasing computer power does not result in new capabilities.  Improvements to computer speed, size, user interface and storage have transformed the way that they are used.  They have gone from being a very specialized piece of equipment to an almost indispensable tool that everyone uses.

Computers from 1940 to 1970 were extremely difficult to use and were applied to very specialized applications.  From 1970 to 1990 computers began to be accessible to the average person, being incorporated in everything from toasters to traffic signals.  The user interface also changes from things like paper tapes and punch cards tapes to screens and floppy drives.  From 1990 to 2010, computers have become increasingly useful until now a business person wouldn't look dressed without a laptop.

Chapter 2: The Mind in the Machine

This chapter seemed to be mostly about the progress to date in the field of computers and implants.

• Introduction
• Lots of advances in the last 50 years.
• Learning network codes
• cochlear implant
• neural filters
• Brain Circuits vs. Computer Circuits
• Brains can learn, computers must be programmed.
• Making a brain larger gives it new abilities
• Making a computer with more memory or a faster processor does not result in new abilities.
• Brains always occur with an accompanying body.
• Human body is able to interact with human beings, etc.
• Computers still have a huge amount of trouble interacting
• Data in brains is about connections and sequence, memory in computers has no associations of this kind.
• Building an AI helps you understand how human cognition works.
• The Brain of John Von Neumann
• Background
• A true renaissance man
• Worked on the Manhattan Project
• Pioneer in the realm of computer science
• Computers (generally) work on serial data and instruction streams.
• The brain works in parallel.
• Point to point vs. associative brain systems
• Point to point: 
• touch, vision, motor system 
• If two points are physically near each other, then the corresponding neurons will have a similar physical relationship
• Associative
• Smell, taste and to some extent hearing
• Take unrelated stimula and relate them 
• Smell #1 = food source
• Smell #2 = predator
• No spatial relationship between sensations

Questions About the Book

I had many questions when I read the book.  One of the reasons for creating this blog is to see if anyone out there would care to speculate or answer some of them:

Anthropology questions

• Is the Boskop find credible?
• How have past civilizations been influenced by the average intelligence of their members?
• What caused previous civilizations to fail?
• How have past civilizations treated exceptionally intelligent members?

Psychology

• How does brain size correlate with intelligence?
• What is the most striking aspect of human beings with larger than average brains?
• Does having a large brain predispose or inure a person from mental disorders?

Medicine/Biology

• Does having a large brain cost more in terms of energy needs for the organism?
• (verification) Is the infant mortality/maternal death rate of human beings higher than in other primates?
• (verification) Did standing upright allow human beings to have larger babies?
• (verification) Do human females, compared to other primates, have wider hips?
• (verification) Does having wider hips make the birthing process safer for both mother and child?
• Why does a child's head have to be large at birth in order to have a large brain later on? Why can't a child be born with a smaller head or body and just grow larger?

Notes on Chapter 1: Big Brains, Bigger Brains

The book starts and ends with discussions about a race or subgroup of humanity that died out 10,000 to 50,000 years ago and that had a brain that was 20% to 60% larger than modern humans.  This is a controversial claim.

 John Hawks has a number of postings that criticize the book. He states that

• The notion of a Boskop race has not been a topic for 50 years.
• The size of the Boskop skull is a fluke, not a race.

He quotes a paper by Ronald Singer from 1958:

It is not obvious that what was justifiable speculation (because of paucity of data) in 1923, and was apparent as speculation in 1947, is inexcusable to maintain in 1958.

He goes on to state that by 1963, D.R. Brothwell could claim that Boskop itself was nothing more than a large skull of Khoisan type, leaving the concept of a "Boskop race" far behind.

He basically states that the Boskop skull is large, but compared with the upper end of the average size of Homo Sapiens brain (1600ml), the Boskop's additional 2000ml is not that large.

Chapter 1: Big Brains, Bigger Brains

• Boskop 
• Possible offshoot of the human race with larger brains than modern humans.
• Named for Boskop, South Africa where they were found.
• While notable at the time, the find has largely been forgotten.
• Are Bigger Brains Better?
• Yes, bigger brains make for a more intelligent animal.
• Brain and Language
• Language is very important
• Uniquely human
• Allows for the transmission of knowledge between generation
• Each generation does not start from scratch.
• Were Boskops smarter?
• Probably
• Why Haven't we Heard of Boskops Before?
• Prejudices - the belief that because we modern humans have some trait then it must be advantageous.
• There is precedence for this: Liebnitz's notation, particle vs. wave theory of light.
• Outline of the book

1. Introduction
2. Brain circuits
3. Genetics
4. Brain structures
5. The neocortex
6. Olfaction and cognition
7. Parts of the brain and what they do
8. How do you get from simple biological machinery to thought
9. Brain differences in humans
10. Species and subspecies
11. Primate and hominid ancestors
12. The Piltdown find
13. Differences in primate brains
14. Speculation about the Boskop

Notes on the Book

While I find the ideas behind the book interesting, trying to get to them can be challenging.  To help myself understand the main points, I have created a summary of what I got out of the book's chapters.

If you took away something different from a chapter, or have some insight into how factual a particular point is, please feel free to chime in.