Evolutionary Psychology and Personality Theories

Evolutionary Theories on Personality

• Darwin's theories of natural selection and sexual selection are the foundation for modern evolutionary psychology
• Two major types of struggles identified by Darwin:
  • Struggle for existence: Competition for survival in a world with limited resources
  • Struggle for mates: Competition for reproductive success through mate choice and same-sex competition
• Evolutionary psychology expanded on Darwin's ideas:
  • Identifying new struggles such as within-family conflicts and conflicts between the sexes

Struggle for Existence

• Species produce more individuals than can survive leading to competition
• Organisms must adapt to environmental pressures like food scarcity, harsh weather and natural disasters
• Evolutionary psychologists have discovered adaptations in humans that help them survive:
  • For example, women have better spatial memory for food locations linked to ancestral foraging

Struggle with Other Species

• Humans compete with predators and parasites; many common fears are evolutionary adaptations
• Some plants developed chemical defenses; children's aversion to certain vegetables is explained by this

Struggle with Other Humans

• Human-on-human competition exists, particularly in tribal societies, where successful warriors tend to have more wives and children
• DNA evidence shows historical conquerors' influence on modern populations
• Human psychology has adaptations for both aggression and self-defense, shaped by conflicts

Struggle for Mates

• Darwin considered traits like the peacock's tail that seem to hinder survival, but explained that it attracts mates
• Male competition (intrasexual selection):
  • Men compete physically and in social status, finances and dominance displays
  • They take higher risk when competing for mates (e.g., reckless behaviors)
• Female mate choice (intersexual selection):
  • Women prefer men with resources, status, ambition and protection abilities
  • Female preferences change based on ovulation cycles
  • Women seek faithfulness and emotional commitment

Struggles Not Considered by Darwin

• Within-family conflicts
  • Parent-offspring conflict: Children try to extract more resources from parents than parents are willing to give.
  • Sibling rivalry: Siblings compete for parental attention and resources
• Stepchildren face higher rates of abuse and neglect
• Battle of the sexes (sexual conflict):
  • Men deceive women by feigning long-term commitment to secure short-term sex
  • Women deceive men by falsely signalling sexual interest to extract resources
  • Coercion as well as sexual deception may evolve as sources of conflict

Evolutionary Psychology: Fulfilling Darwin's Vision

• Evolutionary psychology is realizing Darwin's prediction that psychology will be based on evolutionary foundations
• The field has revolutionized understanding of human mating, social conflicts, and cognitive adaptations
• It explains sex differences in behaviors related to reproduction
• Darwin's theories are expanded by modern research into kin selection, game theory and life history strategies

Future Directions

• Evolutionary psychology highlighted aggression, competition, and deception
• Less focus on cooperation and altruism
• Future research should investigate friendship, alliances and prosocial behaviors

Testing Predictions From Personality Neuroscience

• This research explores how brain structure correlates with personality traits
• MRI scans are used to test a biological theory of the Big Five personality traits
  • Extraversion, Neuroticism, Agreeableness, Conscientiousness, Openness/Intellect
• Key findings:
  • Extraversion linked to medial orbitofrontal cortex, a region for reward processing
  • Neuroticism associated with dorsomedial prefrontal cortex & hippocampus, linked to self-evaluation & emotional regulation
  • Agreeableness linked to superior temporal sulcus and posterior cingulate cortex, regions involved in understanding others' emotions and intentions
  • Conscientiousness correlated with lateral prefrontal cortex, a region responsible for planning and impulse control
  • Openness/Intellect has no strong associations with specific brain regions but some connection to parietal cortex, relevant to working memory and attention control

Voxel-Based Morphometry (VBM)

• A neuroimaging technique measuring gray matter volume in different brain regions

Medial Orbitofrontal Cortex

• Involved in reward processing, linked to Extraversion

Dorsomedial Prefrontal Cortex (dmPFC)

• A region involved in self-evaluation and emotional regulation, linked to Neuroticism

Superior Temporal Sulcus

• A brain area linked to social cognition and understanding others' intentions, associated with Agreeableness

Lateral Prefrontal Cortex

• Involved in planning, impulse control, and goal-directed behaviour, and related to Conscientiousness

Openness/Intellect

• One of the Big Five traits, linked to abstract thinking, creativity, and curiosity