Lecture 1 (Intro to Evo Psych) - Slides Flashcards Preview

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Human Evolutionary Psychology
(General Explanation)

- Brains cause behaviour and brains are influenced by natural selection at the level of the genes. (Environment influences the expression of genes)
- Takes theories from evo-bio and
- Interdisciplinary approach: applied to many fields (Economics, sociology, etc.)
- Understand the mind based on evolutionary past


Human Evolutionary Psychology
(4 Questions)

1) Why is the mind designed the way it is?
- What are the things that helped us in the past

2) How is the mind designed?
- How are these areas interconnected with each other

3) What are the functions of the component parts?
- Do they work together or separately (We can measure IQ, but verbal and reasoning IQ are different)

4) How do inputs from the current environment
interact with mind to produce behavior?
- Will the behaviour occur in other places under the same conditions?


Pre-Darwinian Thinking
(Lamarck and name of theory)

First to use the term "biology" and was the first to get close to answering it before Darwin

Transformationalism - How one species transforms into another through:
1) Use and disuse
2) Inheritance of acquired change


(2 features and who developed it)

Lamarck (1744-1829)
1) Use and disuse: Animals will maintain features that they can use, and if they don't use

2) Inheritance: Next generation inherits those traits but was specific to the parents life history. If a parent didn't use it, then it wouldn't pass on to the child.

The individual changes in response to the environment, not the expression of genes over time.


(Giraffe example and who developed it)

Lamarck (1744-1829)

Giraffe example: thought there was a nervous fluid that would allow the animal to grow a longer neck.

Problems with this: Mechanism is wrong, use example: a blacksmith should have kids with huge upper bodies, disuse: circumcized men should have circumcized women.


(Boat, island and book)

The Beagle (1831-1836)

Thought that Galapagos birds he collected were initially all different species, but were actually the same.

Food availability determined the success of the bird sub species and beak size.

On the Origin of the Species (1859)


Natural Selection
(Book and initial problems)

- Foundation for evolutionary biology
- Populations evolve over the course of generations through a process of natural selection
- On the Origin of the Species (1859)

- Problems: Physical traits that didn't fit into natural selection were problematic (like Peacock tailfeathers)
- Great for mating, bad for survival (large, colourful, metabolically expensive)
- Sexual selection was developed from this


Sexual Selection
(Book and theory)

- Different characteristics can be selected for that may convey reproductive advantages and may even cause individual survival disadvantages.

- The Descent of Man (1871)


The Modern Synthesis
(Who, when and what)

- 1942
- Gregor Mendel (1822-1884)
- Darwin thought that inheritance occurred through "blending"
- Inheritance is PARTICULATE - we pass down individual packets/particles in the form of genes.
- Depending on dominance/recessive patterns we get one trait or another, not a blend
- Synthesis didn't happen until 60 years after Mendel's death


Ethology Movement
(What is it, the 2 tenants of behaviour research)

- The study of animal behaviour
1) Behaviour requires a structure, a physical underpinning that can be measured across individuals
2) Behaviours can influence the traits we observe. Soviet fox experiments ears became round, coats softened and other differences in phynotype


(Who and what)

Who: Konrad Lorenz (1903-1989)

- Imprinting: A pre-programmed form of learning and part of an evolved structure.

Example: Ducklings will imprint on the first thing that moves when they are born.
- It's like learning, but it's preprogrammed at birth - there is a critical period though
-Cat video: imprinted on things that are small and fluffy shortly after giving birth, in this case ducklings


Tinenbergen's 4 Questions

Proximate(direct questions)
1) Ontogeny: How does it develop within an organism.
- What patterns do we observe in the development of an organism from life to birth
2) Mechanism: How does it work?
- How does it occur, from hormones to neurons and organs

Ultimate (Causal)
3) Phylogeny: How did it evolve over generations
- Is it in just humans? Primates, and birds? How far back can we trace it back in our evolutionary record
4) Function: What is the adaption function?
- What is the adaptive value


Human Crying
(Tinenberg's 4 Question Example Proximate Causes)

- Composition of tears themselves: Emotional tears have higher levels of prolactin (social bonding hormone), corticotropin (released in times of stress. They are different than other kinds of tears.

1) Mechanism: Birth, pain, hunger, emotional distress, etc.

2) Ontogeny: Reaches peak at 6 months, stabilizes at 4 months and declines after 2.
- Infants stop crying around 2 when they start to talk - 2 year olds with larger vocabulary cries less.



Colic - Crying for no reason. Humans are only primates that cry while we are held. Crying becomes private when it's penalized particularly within a culture.

- In hunter-gatherer societies, colic doesn't occur as much, but the children are cared for different.

- Infant is consistently carried and can breastfeed whenever it wants, and can monitor consistently.

- Colic could be an evolutionary recent behaviour that is because we are getting away from what we have been doing throughout our evolutionary history for some time.

- Apes don't cry, but they do vocalize. Primates do not vocalize unless they are separated from their parent or injured only.


Sex Differences in Crying

Sex differences - women cry 30-64 times, men 6-17 times a year

Sobbing - uncontrolled crying with vocalizations (65% for men, 6% for women)


Human Crying
(Tinenberg's 4 Question Example Ultimate Causes)

Phylogeny: Acoustic signal, is metabolically costly, associated with condition and alerts predators/parents.

Crying can be an honest or manipulative signal:
- Parents share genes with their children and want each other to be successful, but parents have limited resources and cannot invest completely in all infants typically
- Arms race between parents response to crying and infants pushing back against them. Other siblings are interested in gaining more resources for themselves as well
- Birds cry louder when they are hungrier and more at risk. Healthy birds will cry less so they can use that energy for growth and development
- Babies carried on a sling in Hunter-Gatherers and in primate exhibit less colic basic of constant care and attachment to parent.

4) Function: Elicits care and nuturance, social communication in parental/kin/non-kin,


W.D. Hamilton

- Developed inclusive fitness
- Own RS and the effect of one's own actions on the RS of genetic relatives
- "genes eye thinking" - we have to consider the genes that underly behaviours when we consider any trait


Robert Trivers

- Reciporical altruism
- Parent-offspring conflict
- Parental investment theory


What is evolution? How does it work?

- A process, a change over time, descent with modification genes that provide an advantage will proliferate
- Natural Selection and Sexual Selection


Genetic Drift
(What is it and 2 types)

- Natural and deleterious traits increase due to chance.
- Not an adaptation because it wasn't selected.
- Can result in evolutionary change.

1) Genetic Bottleneck: A random event which only a couple of individuals of that species are surviving but not because they were more fit, but by chance
- Humans creating a genetic bottleneck for elephant seals

2) Founder Effects: Small group of individuals that are the root of a population

- Example: Immigration - Amish of Pennsylvania. Group of people that can be traced back to 200 individuals. Practice Endogamy can only marry without their group. They have all kinds of mutations and aversive health effects(polydactylism)
- Occurs because of small group of individuals and inbreeding


3 Requirements for Selection

1) Phenotypic variation - there must be difference to begin with
- Individuals must differ with respect to the trait or selection pressures cannot act on it.

2) Heritability - must be passsed through the genes
- If no genes underlying the behaviour, it won't be selected (preference for hair colour)
- Variation due to environmental factors will not effect the offspring.

3) Differential reproduction - the change must increase/decrease survival/reproduction


3 Products of Evolution

1) Adaptation: A trait produced and maintained by selection. It is only an adaptation if its designed for its current function
- Environment of evolutionary adaptiveness (EEA)
- Does not have to appear at birth
- Must be rooted in genes
- Must develop among all members/sex of species.

2) By-products: Traits that are not functional, but were carried along with other adaptations.
- Do not solve adaptive problems
- Music may be one of these.

3) Random Effects/Noise: Chance mutations, or perturbations, during development.


Environments of Evolutionary Adaptiveness (EEA)
(What would human EEA look like?)

- A mathmatical sum of where all environment factors are taken into account
- The selection pressures to which traits are adapted.
- If we can figure out the EEA, we can figure out the potential our bodies and brains have.
- EEA for humans may look like hunter-gatherers


4 Types of Adaptation?

- Anatomical, physiological, behavioural, psychological


Psychological Adaptations

- Mental mechanisms shaped by selection
- Internal adaptations such as testosterone in men can influence competition seeking in males
- Focus Attention, organize perception and memory, direct behaviour


4 Questions about Adaptations
(With dinosaur feather example)

1) Is it heritable? Yes.
2) Is it functional? Yes.
3) Does it increase fitness? Yes, may species use it in mate choice, keeps them warm as well.
4) How did it first evolve? Feathers first evolved not for flight (warmth or keeping eggs warm) and may not be strictly an adaptation but may be a by-product. Bellybuttons are by-products of having an umbilical cord, or bones being white.


5 Ways We Study Human Behaviour
(and examples)

1) Paleontological databases: trying to inform function from form.
- Looking at fossil records for when we got opposable thumbs.
- More difficult to infer behaviour from this - must know context for it.

2) Phylogenetic Comparison: what's going on with these traits in non-humans and if they are still going on today.
- Due to common ancestry, we share traits with relatives
- Example: Testee size and mating system. Polyandry is really low and typically female mates with related males in a monogamous relationship

3) Inference from Genetic Patterns
- Example Lactose Tolerance

4) Cross-cultural Comparisons
- Preference for spicey food differs across cultures
- Spices defend against pathogens and by eating them we may confer pathogen resistance to us

5) Observation and Experimentation
- Morning sickness hypothesis


Testee size and Mating System
(What type of question What is sperm competition and example with hypothesis)

Human Mating History Teste
- Phylogenetic comparison question for studying human behaviour.

Sperm Competition: the physical competition between sperm from at least two separate males to fertilize the egg of a single female.

Hypothesis: When sperm competition is high, testicular volume should be high.

Example: Testee-size to body-size ratio for humans is in-between chimps and gorillas. Gorillas exhibit more monogamy, chimps more polygyny. Humans are also in the middle in these mating systems.

- Humans must have a history of polyandry enough to create selection pressure that we can see a difference in teste size compared to gorillas and chimpanzees


Lactose Tolerance
(also type of question, why doesn't it follow Out of Africa path? Advantages, disadvantages)

Lactose Tolerance
- Inference from genetic patterns
- Lactase is naturally produced in childhood until time of weening.
- Pathogens include the pathogens the animal can give us as well as what they can contract themselves

Out of Africa: Wouldn't expect it to be shared by all people, but why wouldn't it be a path through the out of Africa hypothesis?
- Occurred independently through convergent evolution

Advantages: High nutrient density, source of water in drought, 10x more offspring
Disadvantages: Environment must support pastoralism, maintaining animals for heat/cold and have to resist their pathogens.


3 types of mating systems

1) Polygyny: Multiple females to a single male

2) Polyandry: Multiple male mates to a single female mate
- Favours sperm competition

3) Promiscuity: mating with any opposite-sex member if available