Comprehensive Notes on Evolutionary Psychology and Cognitive Heuristics and Social Behavior

Origins and Foundations of Evolutionary Psychology

• Historical Terminology:

  • Sociobiology: This was the primary term used in the $1800$s to describe evolutionary theory in the context of social behavior.

  • Evolutionary Psychology: The field became established as an official sub-field of psychology in the $1990$s.

  • David Buss: He is cited as the most prominent example of an early evolutionary psychologist whose research launched the field.

• Integration with Other Fields:

  • The original hope when establishing the field was that evolutionary psychology would not remain a separate "pillar" but would eventually be integrated into all other areas of psychology (cognitive, developmental, etc.).

  • The current state of the field reflects this; almost all areas of psychology now consider an evolutionary perspective.

• Levels of Explanation:

  • Evolutionary Theory as Ultimate Causation: While cognitive psychology may explain behavior through thoughts (proximate causation), evolutionary psychology seeks the deepest level of explanation: why those specific thoughts or behavioral patterns exist by tracing them to survival and reproduction.

The Logic of Natural Selection and Design

• The Concept of Design:

  • Observation of animals and the natural world reveals high levels of specialization and design (e.g., camouflage in prey, the structure of the eye).

  • Paley's Watch Analogy: Pele (Paley) argued that finding a watch on a beach implies a creator because every part is crucial for telling time. This was the dominant explanation for biological complexity before Darwin.

• Darwin's Breakthrough:

  • Charles Darwin: In the $1800$s, he proposed that nature acts as the "designer" through a gradual process of natural selection.

  • Natural Selection: The environment selects traits best suited for survival. Those without these traits die out, while those with them reproduce.

• Selective Breeding Analogy:

  • Darwin compared natural selection to artificial selection in farming.

  • Example (Cows): Farmers breed cows that produce the most milk and prevent others from reproducing.

  • Example (Hens): Hens that lay many large eggs are allowed to breed, while those that do not become dinner.

• The Unbroken Chain: Every living human is the product of an unbroken chain of ancestors who successfully survived and reproduced, often in extremely harsh conditions.

Assumptions and the Power of Evolutionary Theory

• Core Assumptions:

  1. Variance: Differences must exist within a species (e.g., larger vs. smaller, different colors, taller vs. shorter).

  2. Heritability: Variations must be due to heritage. This is supported by twin studies on heritability and molecular genetic studies.

  3. Selection: Nature must select characteristics that lend better to survival and reproduction (e.g., an owl blending into a tree).

  4. Accumulating Effect: Small changes over generations result in significant shifts.

• Explanatory Examples:

  • Anteaters: If ants move deeper underground, anteaters with long tongues survive and reproduce while those with short tongues starve. Over generations, the average tongue length increases.

  • Antelopes: When a pack of lions is introduced, faste antelopes survive and slow ones are eaten. Over many millions of years, the population becomes substantially faster.

• Power of the Theory: The power of a theory is measured by the ratio of explained phenomena to assumptions: $\text{Power} = \frac{\text{Explanations}}{\text{Assumptions}}$. Evolution is considered arguably the most powerful theory because it explains a vast amount of biology assuming very little.

Designer Flaws and Evolutionary Lag

• Imperfections in Engineering: Evolution does not produce perfect designs, but rather workable adjustments from the past.

  • The Eye: The optic nerve goes over the retina instead of under it, creating a blind spot.

  • Giraffes: They have a very long artery that makes them prone to injury and early death; it could have been fixed by connecting higher in the neck.

• Lack of Foresight: Natural selection cannot "plan ahead" for millions of years; it only makes changes based on immediate survival advantages.

• Evolutionary Lag: Evolution is a lagging process because it solves problems from the ancestral past while explaining behaviors in the present.

Three Products of the Evolutionary Process

• 1. Adaptations:

  • Solutions to specific problems of survival (e.g., being faster, opposable thumbs, large brains).

  • Psychological adaptations include intelligence, creativity, and certain personality traits.

• 2. Byproducts:

  • Accidental consequences of adaptations that were not directly selected for.

  • Example (Driving): The ability to drive a car is a byproduct of high intelligence and cognitive ability, not an adaptation for Neolithic survival.

  • Example (Belly Button): The byproduct of the umbilical cord (the actual adaptation).

  • Buss's Homicide Fantasy Theory: David Buss argues homicidal fantasies are adaptations for managing conflict in the past. Other theorists disagree, suggesting aggression is the adaptation and homicide is a byproduct.

  • Female Orgasm Debate: Some argue it is an adaptation (encouraging sex for reproduction); others say it is a byproduct of shared fetal development time when male and female anatomy is identical (similar to male nipples).

• 3. Noise:

  • Random variation in byproducts that does not affect survival.

  • Example: Variation in belly button shapes (innies, elbys). Because shape doesn't impact survival, it is not selected for or against.

Sexual Selection: Beyond Survival

• The Peacock Paradox: Large, bright feathers make survival harder (predators, flight difficulties). Darwin famously had "nightmares" about these because they defied natural selection principles.

• Sexual Selection Types:

  1. Intersexual Selection: Selection by the opposite sex (e.g., female peacocks preferring males with bright feathers).

  2. Same-Sex Competition (Intrasexual): Evolution of weapons for competition (e.g., horns, tusks, antlers). Winners of these battles get to reproduce.

• Size Dimorphism: Whichever sex is "choosier" (usually females in humans), the opposite sex will typically evolve to be taller and larger. Historically, taller men reproduced more on average, leading to the current average height difference between sexes.

Cognition, Heuristics, and Biases

• Heuristics: Mental shortcuts evolved for immediate judgment to increase survival chances.

• 1. Framing Effects: Decisions are affected by how information is presented.

  • US Disease Scenario: When framed as "$200$ will be saved," $72\%$ choose Program A. When framed as "$400$ will die," only $22\%$ choose Program A ($78\%$ choose B).

  • Loss Aversion: Humans are more sensitive to negative loss than positive gain. For example, things become more valuable when we own/sell them ($\$2.50$) than when we buy them ($\$2.00$).

  • Monkey Keeper Study: Monkeys preferred Keeper A who starting by giving $1$ treat and occasionally "bonused" with $2$, over Keeper B who started with $2$ and then "under-delivered" by giving $1$ half the time.

• 2. Ignorance of Base Rates:

  • John Example: Even when base rates of engineers ($30$) and lawyers ($70$) are given, people classify John as an engineer based on the stereotype of being "socially awkward" and liking "mathematical puzzles."

  • Medical Diagnostic Test: Disease strikes $1$ in $1,000$. Test has a $5\%$ false positive rate. If you test positive, the actual probability of having the disease is approximately $2\%$. This is calculated by seeing that out of $1,000$ people, $50$ will have a false positive and $1$ will actually have the disease ($\frac{1}{51} \approx 2\%$).

• 3. Availability Bias: Estimating frequency based on ease of recall.

  • Jewish Population: The average American guesses $25\%$, while the actual number is $2\%$.

  • Dictionary Search: People believe there are more words ending in -ing than -ng, despite every -ing word by definition ending in -ng.

  • Shark Attacks vs. Potato Salad: People overestimate shark deaths because of news coverage, but there are $1,000$ times more deaths from food poisoning (potato salad).

• 4. Confirmation Bias: Interpreting information to confirm existing beliefs.

  • Teacher Study: Teachers told random students were "gifted" (Group A) or "low potential" (Group B) gave higher grades and more attention to Group A based on the false labels.

Altruism and Social Emotions

• Reciprocal Altruism: Altruism exists because working together is often better for individual survival than being solitary.

  • Examples: Monkeys grooming non-kin, warning cries in the forest (birds/deers), and humans caring for others' offspring.

  • System Maintenance: This only works if groups detect and punish "cheaters" (those who take without giving). Humans have evolved a high sensitivity to injustice.

• The Prisoner's Dilemma: A model of cooperation and defection.

  • Criminal Case: Two criminals split. If both talk, they get the max sentence. If neither talks, they get a small sentence. If one talks (defects) and the other doesn't, the snitch goes free.

  • Examples in Society: Nuclear weapons (everyone has them so no one is victimized, but everyone is worse off due to cost) and Divorce Lawyers (both pay for lawyers to avoid being at a disadvantage, resulting in less money for both).

• Golden Balls Game Show: A real-world application where contestants choose to "split" or "steal" a pot of money.

• Ultimatum Game: Person A is given $\$10$ and offers a portion to Person B. If Person B rejects, no one gets money.

  • Rational logic says Person B should accept $\$1$.

  • In reality, people offer $\$4$ or $\$5$ because they know Person B will reject $\$1$ out of spite/irrationality.

  • Advantage of Irrationality: Irrational/unpredictable people are harder to exploit because their responses are not measured or predictable.

Cultural Evolution and Groups

• Environmental Influence: High altruism societies develop in brutal conditions where resources are scarce. Plentiful environments (e.g., the Amazon) show more competition.

• Cultures of Honor: Developed among groups who couldn't rely on law (e.g., Scottish Highlanders, herders, Western cowboys).

  • The American South: Settled by Scots-Irish herdsmen. Lacking centralized control, they developed a reputation for fierce retaliation to protect their herds.

• University of Michigan Study (1996):

  • Conducted by Coleman (Cohen) and colleagues with $100$ students.

  • Procedure: A TA walked into students in a hallway and called them an "asshole."

  • Findings: Southern men showed significantly higher cortisol and testosterone spikes and higher scores on psychological measures of provocation compared to Northern men.

Questions & Discussion

• Question from student: Can that [University of Michigan] study still be valid because they only studied like half the population, there weren't any women, so why would it like—well, couldn't generalize it to women from the North or from the South?

• Response: The lecturer clarified that the study's results are valid for the group studied (men from the North and South). It was not intended to suggest general moral superiority, but rather to illustrate how cultural environments—physical, social, or political—shape psychological response patterns in specific groups.

Classroom Exercise

• Activity: Small group reverse engineering of human psychology.

• Task: Identify a current human psychological feature and determine how it might have served as an adaptation for survival or reproduction in the ancestral past.