Robert Sapolsky Evolution Lecture Notes

https://www.youtube.com/playlist?list=PLqeYp3nxIYpF7dW7qK8OvLsVomHrnYNjD

www.youtube.com

Prof. Robert Sapolsky's course "Human Behavioral Biology". Stanford University. This course covers the following topics: - Behavioral Evolution - Molecular G...

LECUTURE 3

Tournament species vs pair-bonding species

(Tournament species evolve antimother prochild genes)

Adelphic polyandry = two brothers rule pack of women

Or woman marries all the brothers

Group selection debunked in 1960, but a new form is emerging

Group Selection on Optimal Subculture

Geographic isolation - isolated group is more interrelated - more cooperation, reintegrated into mass population,  infects mass population with cooperation culture (reciprocal altruism)

(Calvinism conquered Europe in this way)

Group Selection on Optimal Social Trait

Aggression beats passivity 1 on 1, but groups of aggressive people hurt each other and lose to groups of passive people, so passivity wins at group level.

Adaptationist fallacy - all traits exist because they evolved for a good reason

LECTURE 4 - MOLECULAR BIOLOGY

4 letters (sugars) in DNA code

3 sugars create 1 amino acid (4* 4*4=64 possible amino acids)

3 types of Mutations

1. point mutation  - swap out one sugar for another

2. deletion mutation - remove one sugar in the sequence, and frame shift all of the DNA code to majorly alter everything downstream from that

3. insertion mutation - add one sugar in the sequence, and frame shift all of the DNA code to majorly alter everything downstream from that

Testicular Feminization syndrome - genetically male - XY, they have testes in their stomach, making lots of testosterone, yet externally female because the testosterone receptor mutated and can't absorb testosterone.

___ = the enzyme that produces testosterone is mutated to a slower less efficient form, so during childhood, they look like a girl because testosterone isn't high enough, but when puberty strikes, DNA commands more testosterone to be produced, it is still on the low side, but it is produced in enough quantity to have the female begin to transform into a male. 

Fox P2 gene = something to do with language, yet many animals have it - use it for communication. Bird singing; mouse ultrasonic screaming.  Lots of adaptive differences in human version of FoxP2.

60 ways to code 20 amino acids, so each amino acid can be coded in 3 ways.

Measure Evolutionary Forces By Rate of Amino Acid Mutation

If an amino acid experiences 33% change, you can predict that changes to this amino acid are not consequential to the success of the species - benign mutation.

If an amino acid experiences 99% change over time, you can see that there was strong positive selection for changes in excess of random.

If an amino acid experiences 1% change over time, you can see that there was strong aversion to changes - meaning this amino acid is very important - stabilizing selection.

1 gene codes for 1 protein

You chare 50% of your DNA with a sibling. (50% same VERSION of same CATEGORY of gene)

Humans share 98% of their DNA with chimps. (98% same CATEGORY of gene)

GRADUALISM VS PUNCTUATED EQUALIBRIUM

1980 gradualism was challenged by Gould and Eldridge (Marxist)

CRITICISM OF PUNCTUATED EQUALIBRIUM

1. period of "rapid change" is actually 100,000 years, plenty of time for normal evolution

2. periods of "stasis" reflected in the fossil record only show stasis in traits that influence the shape of fossils and provide no information regarding stasis of internal evolution of things like the brain.

3. what is the molecular mechanism for stasis and rapid change?

EXONS and INTRONS

EXON = Blocks of code that produce Amino acids

INTRONS = intermittent code between blocks of code

Modular construction of genes - splicer enzymes come in and CUT OUT the INTRONS

Modular nature means that different enzymes can construct different varieties of proteins by playing with the order of the modules.

1 gene can generate 7 types of protein.

Splicing enzyme and degradation enzymes.

Tissue based expression of genes - different cells apply different enzymes to the genes.

Long stretches of NON-CODING DNA between genes (junk DNA).

95% of DNA is NON-CODING - instruction booklet for genes (ON/OFF switches - environmental activation switches)

Transcription factor proteins get attracted to the DNA switches.

Multiple switches can occur before the gene.

You can activate it in different ways by providing different transcription factors.

A transcription factor can activate or disactivate an entire network of genes because if you turn of the gene for a transcription factor, it turns off ALL GENES connected to that transcription factor.

ENVIRONMENT IMPACTS PROTEIN PRODUCTION

Intra-cell environmental gene expression

Something happens in the environment of the cell (running out of energy), which activates some transcription factor which will activate a network of genes to produce protein for grabbing more energy from outside the cell.

Inter-cell environment gene expression (HORMONES - blood borne )

A foreign cell sends a messenger protein that connects to a receptor on the external wall of a cell - which triggers a chain of events that produces a transcription factor for altering the internal gene expression of the cell. 

External environment gene expression (pheromones)

A foreign smell or sense can trigger reactions that trigger transcription factors.

Chromatin encapsulates and protects the DNA

Chromatin must OPEN to allow transcription factors to enter.

Some DNA regulates the modeling and remodeling of chromatin.

You can make chromatin easier or harder to open.

You can permanently silence genes by hardening the chromatin and not allowing transcription factors in.

Epigenetics = regulation of access to DNA sequences (overrides transcription factors)

Epigenetics = environment changes DNA by changing accessibility

Steve Sumi studies primate behavior.

Mothering-style can permanently impact over 4000 genes and their accessibility.

LECTURE 5

Jumping genes

Lady studied corn - discovered jumping genes - plant defense mechanism - real time mutations and evolution

Humans use jumping genes for immune system and brain development. 

Evolution of regulators creates punctuated equilibrium evolution, faster  than gradualism.

Foxes bred for domestication become doglike - selecting for child-like features - niceness is the same network as childhood dna.  They even start to wag their tails.

LECTURE 6 - Behavioral Genetics I

Swedish adoption study on schizophrenia

Environment schizophrenia synergizes and magnifies biological schizophrenia.

Rat study on glucocorticoid impact on fetuses

Prenatal environment - what happens to fetus when mom is stressed (increase in glucocorticoids )

1. smaller brain

2. thinner cortex

3. less learning abilities

4. more prone to anxiety

5. fewer benzodiazepines receptors

6. more old age cognitive decline

7. weaker ability to recover from stress (less ability to resolve glucocorticoids in your system because certain brain cortex is smaller)

8. higher baseline of stress chemicals in your system (glucocorticoids)

9. grandmother effect (if grandma is stressed, daughter will be stressed, and the granddaughter will also be stressed)

Prenatal metabolic programming

If prenatal environment is lacking resources (mother is starving), the fetus will activate DNA to make permanent changes to their digestive system to make it more efficient.

1. Insulin production is more reactive - tries to eat up and store sugars as fast as possible

2. Kidney's increase their salt-storing capacities

Fetal environment

During WW2, the Germans screwed the Dutch over one winter and took all their food for the war effort.

A study was done on the children who were fetuses at the time of the famine.

These children had a 19 fold increase in

1. obesity

2. hypertension

3. diabetes

4. metabolic syndrome

They found that Dutch fetuses in the 1st trimester did NOT have this effect.

Also, newborns that were born before the famine did NOT have this effect.

The conclusion is that the metabolism permanently programs itself during the 2nd and 3rd trimester.

The metabolic programming becomes more extreme based on how extreme the environment is.

Prenatal Learning

Inject sucrose syrup into womb so fetus can drink it. 

After birth, the newborn prefers drinks with sucrose in it.

Fetus's hear their mom's voice from within the womb.

Mothers read "The Cat in the Hat" over and over during 3rd trimester.

Newborns express their preferences by sucking their fingers more.

Newborns were then presented with a test for what material they liked listening to.

Newborns prefer hearing "The Cat in the Hat"

Fathers read "The Cat in the Hat" - doesn't work.  Only sounds from the mother work.

Rat Anxiety Study

Darlene did prenatal surgery on fetuses from high-anxiety mothers and transferred them into low-anxiety mothers.  The rats developed anxiety based on the prenatal environment, not their genetics.  If they were transferred to a low-anxiety womb, they would turn out to be low-anxiety rats.  If they were left in the womb of their high-anxiety mother, they would become a high-anxiety rat.

Fetus is not 50/50 mother/father

The egg contains a mitochondria - with mitochondria DNA.  The sperm has no mitochondria, hence ALL mitochondria DNA comes from the mother. 

The egg contains transcription factors, the sperm does not.  Toxins can destroy transcription factor x in the egg, and therefore permanently turn off a pair of DNA activity to both 1) create more transcription factor x, 2) express a gene dependent on transcription factor x. (Lamarckian genetics)

Traits can arise from Environment

Taller and more attractive people are treated better by strangers growing up.

Being treated better by strangers increases EXTROVERSION.

Birds growing extra colorful and iridescent feathers can get bullied and picked on more by their peers.

Birds are reduced to subordination - personality becomes more submissive.

Traits can arise from Intermediating Trait.

About 70% heritability of political party affiliation.

Based on aversion to ambiguity (opposite of openness).

Kohlberg stage of moral development.

Heritability of Aggression - Lower threshold for pain sensitivity - they get hurt easier

The Nurture aspect of Non-Aggression

If rat mothers lick and groom their children frequently, the children will be boosted in their health and brain size.  The mother's behavior will also cause the children to be similar types of mothers.  If a rat is neglected by his mother, but is then transferred to a very affectionate foster mother, the child will develop the affectionate behaviors of the foster mother.

LECTURE 7 - Behavioral Genetics II

Heritability vs Environment

earrings = heritability causes varance (only girls wear earrings)

fingers  =  environment causes variance (only construction working environments)

LECTURE 8 - Recognizing Relatives

Some animals are based on smell, some are based on cognitive function.

Smell vaginal fluid, smell something similar to one's self, smell saliva, smell urine, smell pheromones, etc.

Fish operate cognitively - a fake male was introduced to a male fish's woman.  After the female gave birth, the father male was less willing to care for the child because he figured that the child might be fathered by the fake male. 

Human mothers are very good at recognizing the smell of their baby.   Human babies are very good at recognizing the smell of mom (test by placing two smells near the baby - the baby will spend more time aiming its head towards mom's smell.  Babies can also recognize mom's voice.  Babies cannot recognize father's smell or voice. 

LECTURE 9 - Ethology

Behaviorists focused on measuring cause and effect of behavior in a lab.

Ethologists focus on studying behavior in natural environment or simulations of nature.

Fixed action patterns - animals have different hard wired instinctual behaviors built in that they never have to learn, but they can all learn to get better or smarter at the behavior

Many animals are afraid of heights without every being exposed to a cliff, except sloths.

Some monkeys are naturally afraid of eagles, leopards, and snakes.  They communicate threats based on if its from above or below.  Monkeys don't trust the warnings from younger monkeys because they know that kids probably haven't mastered their detection skills yet.

Bees communicate newly discovered food source information via a dance.  They wiggled in a figure 8 motion.  The axis of the figure 8 was the direction to the food source.   The longer the bee danced, the further away the food source was.   The more frantically it wiggled its butt in the dance, the more exciting the food source was.   Von Frisch was able to prove this dance contained directional information by rotating the beehive after the instructions were given.  The bee's orient their direction based on the hive entrance.  So when the hive was rotated, they would fly in the wrong direction to the proportion of error introduced by rotating the hive.  Robotic bees can be programmed to do the dance in a certain way and direct the hive of bees as desired.

A elk making a mating call can trigger an ovulating response in female deer, merely triggered by sound.

Tickle a rat on their ribcage and they giggle.  Other rats will be triggered to investigate the source of the giggle sound.

Human females voices go higher when ovulating, and males can detect this.

Human stress information is contained in the smell of their sweat.  If a human smells someone else's stressed out sweat, they will not know it, but their amygdala activates (fear processing).  Also, if you show humans pictures of faces, they are more likely to recognize a face as "scared" after smelling stressed out sweat.

Electric fish communicate via electricity songs.  Territorial songs, male competition songs to jam signals of other males, sibling songs. 

Vibration - insects communicate with vibrations. 

Elephants have tiny organs in their feet for sending out vibrations through the earth to communicate with other elephants. 

Tactile communication - chickens prefer a fake mother with a chicken-like texture to a fake mother with milk.

Female hamsters arching back when ovulating to make it easier to mount them.

Apes type animals have more cognitive oriented design.  Baboons don't know how to be instinctual mothers.  Their babies have better survival rates the more experience they have.  They have to learn how to feed their babies milk properly.  Meerkats have to learn how to eat properly.  Parents teach their kids how to eat scorpions safely.  

Tool making - Whales (cetaceans) can make tools.  All ape types can make tools.  Baboons can learn to strip bark off a stick, insert it into a termite mound, and eat the termites that attach to the stick.  Chimps can learn to use tools to break open nuts and eat them.  They can combine tool concepts, like a hammer and an anvil.  Chimps can fashion wood into a weapon.  Daughters learn faster than sons because sons aren't good at paying attention.  The larger the social group, the faster the kids learn the tool use.   Baboons can learn from chimps as well. 

Imprinting - Konrad Lorenz ducks.  Certain period of time when anything moving is statistically likely to be mother, so genes trigger the bonding process. 

Prepared learning -

• Sauce Bearnaise syndrome: Stomache pain after a meal during an opera - you associate the stomache pain with the food you ate, not the music you listened to.  Your body is prepared to learn food lessons when eating.  Sauce Bearnaise became incredibly nauseating in smell ever since the first bad experience. 

• Humans do not instinctually fear spiders (since some cultures love spiders), but we have prepared learning to learn to fear them. 

• Humans and monkeys have prepared learning for identifying snakes.  If you show primates a picture of a scene, and then flash an updated picture of the scene; primates are better at detecting if a snake entered the scene than identifying a different change to the environment.   Also, better at detecting an animate object entering the scene than an inanimate object. 

• 
  

Self-awareness - Chimps have self-awareness of a self-identity, because if you draw a shape on their face, and let them see themselves in a mirror, they will be confused about the shape on their face.  Marmoset monkeys don't have self-awareness of their face, because that isn't what they pay attention to.  If you put the mark on their necks, then they will notice it and become confused, because that is something they pay attention to. 

*Ethology = Interview animal in its own language. 

Theory of Mind - The ability to understand that each mind has a different set of information, and to have empathy for the knowledge gap between minds.  (Toy doll goes into the washing machine example.  The parent knows that the child doesn't know where the toy is, because the parent understands "theory of mind")

LECTURE 10 -  Introduction to Neuroscience

LECTURE 14 - LIMBIC SYSTEM

Minute 37:00

If humans want to move 1 finger, an intelligent design would have the brain send 1 signal to the finger to move. 

But in reality, our nervous system comes as baggage from our ancestors.  Our ancestors didn't need to move fingers independently, so the neural structure sends a signal to all 5 fingers simultaneously to move together.  As we evolved closer to apes, our need to control fingers separately grew, so we evolved a 2nd layer of neural connections that sends a 2nd signal saying "if you received the signal to move all 5 fingers, I want you to turn off fingers 1, 3, 4, and 5."  Evolution patches new features onto messy old software instead of redesigning the whole system.