Evolutionary Perspective in Psychology

Course Coverage Exclusions

  • Non-Tested Material: Students will NOT be tested on the following specific boxes in Chapter 8:     * A Closer Look Box: ‘Could ADHD Have Evolved as an Adaptive Trait?’     * Canadian Highlight Box: ‘Depression as an Evolved Mechanism: The Adaptive Rumination Hypothesis’

Evolutionary Continuity and Foundations

  • Non-human Personalities: Research indicates that closely related species share similar personality traits.
  • Evolutionary Continuity: This principle suggests that all animal capacities and behaviors exist in continuity with other species. There is no hard break between animal and human behavior.
  • Human Exceptionalism: The idea that humans are fundamentally different or exempt from biological laws is not well-supported by evolutionary evidence.
  • Evolution and Natural Selection: Evolution is driven by the process of natural selection, often referred to as survival selection.     * Adaptations: These are created and change over time to solve specific problems posed by nature.     * Hostile Forces of Nature: These include factors such as food shortages, diseases, parasites, and predators.     * Selection Process: Variants that help an organism survive these hostile forces increase the likelihood that the organism will reproduce and pass on those traits.

Sexual Selection

  • Definition: The evolution of characteristics based on mating benefits rather than direct survival benefits.
  • Intrasexual Selection: Competition between members of the same sex (e.g., two males fighting) for access to mates.
  • Intersexual Selection: The process where members of one sex choose a mate based on their preferences for certain qualities.

Inclusive Fitness and Evolutionary Products

  • Genes and Inclusive Fitness: The modern evolutionary view focuses on the gene as the unit of selection. Inclusive fitness includes an individual's own reproductive success plus the effects the individual has on the reproductive success of genetic relatives.
  • Products of the Evolutionary Process:     * Adaptations: The primary products of the selective process; they are reliable solutions to adaptive problems.     * Adaptive Problem: Anything that impedes survival or reproduction.     * Byproducts of Adaptations: Incidental effects of adaptations that are not themselves considered adaptations (e.g., the white color of bones is a byproduct of their calcium structure).     * Evolutionary Noise: Random variations that are neutral to selection and do not affect the functioning of adaptations.

Evolutionary Psychology Principles

  • Core Premise: Humans carry adaptive mechanisms that led to the success of our ancestors. Human nature and personality are viewed as a collection of evolved traits and mechanisms.
  • Communion vs. Agency: Communion (getting along with others) is considered more important for survival than agency (getting ahead or status-seeking).
  • Domain Specificity: Psychological adaptations are designed to solve particular problems. A different adaptive problem requires a unique, specific solution.
  • Numerousness: Because humans have faced a vast number of adaptive problems, we possess a large number of corresponding adaptive mechanisms.
  • Functionality: Psychological mechanisms are specifically designed to accomplish particular adaptive goals.
  • Research Methods:     * Deductive Reasoning Approach: A "top-down," theory-driven approach where researchers start with a theory and derive hypotheses.     * Inductive Reasoning Approach: A "bottom-up," data-driven approach where researchers observe phenomena and then develop a theory to explain them.

Psychological Adaptations for Survival

  • Fear and Phobias: Evolved to avoid hostile forces of nature.
  • Selection of Mates: Evolved to ensure reproductive success.
  • Detection of Cheaters: Evolved to maintain social exchange and cooperation.

Social Adaptations and the Need to Belong

  • The Need to Belong: One of the most basic human motivators, driven by the goals of status and acceptance.
  • Social Anxiety: Evolved because being excluded from a group was historically damaging and life-threatening. This distress about negative evaluation by others helps prevent social exclusion.
  • Group Cohesion: External threats increase group cohesion. Intense threats lead to increased social bonding.
  • Resource Management: Group membership allows individuals to acquire and share resources more effectively, further strengthening the bond.
  • Self-Esteem as a Monitor: Self-esteem acts as a monitor for social inclusion. Individuals who spend more time with others generally report higher self-esteem.
  • Failure to Satisfy the Need to Belong: Results in "social pain" and poor physical health indicators:     * High blood pressure.     * High perceived stress.     * High cortisol levels.

Altruism and Interspecies Observations

  • Bonobos: A sub-species of chimpanzees that are more affectionate with one another and solve social conflicts through sexual behavior rather than aggression. They exhibit high levels of empathy.
  • Rhesus Monkeys: Observations show they refuse to pull a chain for food if doing so sends an electric shock to a companion.
  • Helping Others: Helping behavior is tied to the recipient's ability to enhance the inclusive fitness of the helper. People are more likely to help siblings than nieces or nephews because they share more genetic material.
  • Interspecies Altruism: Examples include pigs, elephants, and crows.     * Humpback Whales: Documented saving other species from attacks by killer whales, despite no identified material benefits for the humpback whales themselves.

Altruism in Humans

  • Cross-Cultural Studies: Research in the US and Japan shows humans are significantly more likely to help highly related kin in life-and-death situations.
  • Insignificant Help: For minor tasks, people tend to help those most in need, including the very young and the very old.
  • Costly Help: In high-stakes/life-threatening situations, help is predominantly directed toward the young, who have higher reproductive value.
  • Proximity: Having kin in close proximity significantly increases an individual's odds of surviving.

Universal Emotions

  • Perspectives on Emotion: Evolutionary theory suggests emotions are universal and recognized in the same way across cultures.
  • Facial Recognition Study: Research using pictures of faces representing 77 primary emotions showed high agreement across many different countries.
  • Fore of New Guinea: A study of this group, who had no contact with outsiders, confirmed the universal pairing of specific facial expressions with specific emotions.

Aggression and Warfare

  • Narcissism: Linked to the pursuit of status. Intra-species warfare and organized aggression are found primarily in chimpanzees and humans.
  • Biological Basis: Low expression of the ADRA2CADRA2C gene is associated with an increased likelihood of a "fight-or-flight" response. This can lead to increased fighting over resources.

Sex Differences in Evolution

  • Predicted Sex Differences: Males and females will differ precisely in the domains where they have faced different adaptive problems.
  • Theory of Parental Investment and Sexual Selection: Females can only bear a small number of offspring and thus must be more careful in mate selection. Males must compete for access.
  • Effective Polygyny: There is a variance in reproduction between the sexes. Higher variance in one sex (usually males) leads to more intense competition within that sex.
  • Jealousy Strategies:     * Females: Always certain of maternity; they tend to be more jealous regarding emotional infidelity, as it threatens the loss of resources/commitment.     * Males: Face paternity uncertainty; they tend to be more jealous regarding sexual infidelity, as it jeopardizes the certainty of passing on their own genes.     * Study (Harris): Found that while both sexes are distressed by sexual infidelity, attachment-fertility suggests they may experience jealousy similarly under certain conditions, with some variance in how they prioritize emotional vs. sexual threats.
  • Mate Preferences:     * Females: Place higher value on a potential mate's financial resources and provisioning ability.     * Males: Place higher value on a female's physical appearance (a cue for fertility).     * Shared Values: Both sexes highly value kindness, understanding, and an exciting personality.

Individual Differences and Environmental Triggers

  • Environmental Cues: Individual differences can be explained by the specific conditions people are exposed to (e.g., cues to a partner's infidelity evoking jealousy).
  • Early Life Stress: Differences in neuroticism may stem from different levels of stress and demands in the early life environment.
  • Childhood Adversity: Correlated with lower agreeableness and higher levels of anger and aggression.     * Australian Study: Found that children with high adversity showed increased risk for neuroticism, negative affect, and aggression.     * MAOA Gene: Antisocial and violent tendencies were found primarily among children with low MAOAMAOA activity who also experienced adversity. There was 00 correlation found with extraversion or psychoticism.
  • Father Presence/Absence: The presence or absence of a father between the ages of 11-−-5 triggers specific sexual strategies:\n    * **Father-Absent**: Expectations that parental resources are not reliable and relationships are not enduring. Results in early sexual maturation, early sexual initiation, frequent partner switching, and impulsivity. Others are perceived as untrustworthy.\n    * **Father-Present (Reliable/Investing)**: Expectations that people are trustworthy and relationships endure. Results in delayed sexual maturation, later sexual activity, and a search for long-term, securely attached relationships with heavy investment in few children.\n\n# Contingencies and Frequency-Dependent Selection\n\n* **Contingencies Among Traits**: Certain psychological traits are more adaptive when paired with specific physical traits. \n    * **Physical Dominance**: Being big and strong makes a quick temper a more adaptive (effective) trait.\n    * **Extraversion**: More advantageous for those who are physically attractive and strong.\n    * **Social Dominance**: High social status makes narcissistic and psychopathic traits more advantageous for "getting ahead."\n* **Frequency-Dependent Selection**: The reproductive success of a trait depends on its frequency relative to other traits in the population. \n    * If a trait becomes too common, its competitive advantage decreases due to social response.\n    * **Cheating**: Maintained at a low frequency in populations. If everyone cheats, the gain is lost as the system collapses.\n    * **Psychopathy**: Provides a survival advantage only at a low frequency. If too prevalent, others learn to detect and deal with it, neutralizing the advantage.\n\n# Optimal Variance and Balancing Selection\n\n* **Environmental Variation**: Different levels of a trait are adaptive in different environments over time. There is no single "optimal" level of a trait like extraversion.\n    * **Food Scarcity**: High risk-taking and cooperation are adaptive.\n    * **Food Abundance**: Low risk-taking is more adaptive.\n    * **Disease Outbreak**: Low openness and low extraversion are adaptive to avoid contagion.\n    * **Low Disease Risk**: High openness is more adaptive.\n* **Balancing Selection**: This occurs when there is no unconditionally optimal value for Big Five traits. Each has costs and benefits:\n    * **Neuroticism**: Benefit is increased vigilance to danger; cost is high stress reactivity.\n    * **Extraversion**: Benefit is increased mating success; cost is increased physical risk and family instability.\n    * **Conscientiousness**: Cost is an unwillingness to take chances/missing spontaneous opportunities.\n* **7RAlleleoftheAllele of theDRD4$$ Gene*: Associated with novelty-seeking and exploration.      Rates are higher in North America and lower in Asia.     * Associated with migratory/nomadic populations needing to be exploratory in new environments.     * *ADHD Connection*: In these contexts, traits associated with ADHD provided an adaptive advantage.

The Adaptive Landscape and Difference-Detecting Mechanisms

  • Social Complexity: Personality differences are most pronounced in social species because social environments create more complex problems to solve.
  • Difference-Detecting Mechanism: Humans have evolved the ability to notice and remember individual differences relevant to solving adaptive problems. We look for the Big Five in others for specific reasons:     * Extraversion/Dominance: "Who is likely to rise in the hierarchy?"     * Agreeableness: "Who is likely to cooperate with me?"     * Conscientiousness: "Who is reliable and dependable?"     * Neuroticism: "Who will drain my resources or monopolize my time?"     * Openness/Intellect: "Who should I go to for advice?"