Evolution and Natural Selection

Evolution and Natural Selection

• Humans descend from ancestors who survived to reproductive age and reproduced.
• Adaptive mechanisms help humans succeed.
• Human nature and personality comprise evolved mechanisms.
• Evolution involves change over time and adaptation to the environment.

Natural Selection

• Charles Darwin proposed that adaptations arise and changes occur over time through natural selection.
• Organisms produce more offspring than can survive.
• Adaptations help descendants inherit variants, leading to ancestors' success.
• Successful variants persist, while unsuccessful ones diminish.

Adaptations

• Adaptations feature inherited solutions to survival and reproductive challenges.
• Adaptations are primary products of selection.
• Adaptive problems impede survival or reproduction.
• Adaptations have special designs which entails efficiency, precision, and reliability.

Sexual Selection

• Some mechanisms threaten survival, like a peacock's plumage or a stag's antlers.
• Evolution by sexual selection includes traits evolved for mating success.

Sexual Selection Forms

• Intrasexual competition entails same-sex members competing to access the opposite sex; an example is a lion pride
• Intersexual competition is when one sex chooses a mate based on preferences for certain qualities, like the peacock.

Natural vs. Sexual Selection

• Genes are DNA packets inherited from parents.
• Genes are the discrete units of inheritance.
• Genes as inheritance units led to understanding natural and sexual selection as different forms of the same process.

Genes and Inclusive Fitness

• Differential gene reproduction is the reproductive success compared to others.
• Organisms or genes with more reproduction become more prevalent
• Inclusive fitness theory (Hamilton, 1964) covers individual reproductive success, plus effects on genetic relatives' reproduction, weighted by genetic relatedness.

Evolutionary Process Products

• Adaptations are the main products of selection.
• Byproducts of Adaptations are incidental effects.
• Noise or Random Variation is neutral regarding selection, like earlobe shape.
• Noise/random variation comes from random genetic differences unrelated to survival or reproduction.

Evolutionary Psychology Principles

• Adaptations solve specialized adaptive problems.
• Food preferences do not help with finding a mate.
• Selection creates specialized mechanisms for adaptation.
• Expectations of many psychological adaptations exist because diverse adaptations are a need when solving adaptive problems.
• Psychological adaptations designed to accomplish adaptive goals.

Testing Evolutionary Hypotheses

• Analysis levels exist in evolutionary psychology.
• General evolutionary theory exists.
• Middle-level evolutionary theories involve reciprocal altruism plus parental investment along with sexual selection as well as parasite-host co-evolution.
• Specific hypotheses entail falsifiable predictions.

Research Modes

• Deductive reasoning goes "top-down" with theory-driven approach.
• Inductive reasoning goes "bottom-up" with data-driven method
• Both are valid ways of conducting research.

Human Nature

• Grand theories of personality should include human nature.
• Human nature results from evolution.
• Successful psychological mechanisms help humans survive and reproduce.

Human Nature Examples

• Over time, successful mechanisms spread broadly and define all humans.
• The need to belong is a key factor.
• Social anxiety helps ensure social interaction that results in reproductive success.
• Social exclusion is "painful" and causes social pain.
• Social exclusion might share brain circuitry with physical pain

Helping and Altruism

• Helping is linked to the person’s relatedness.

Human Emotions

• Ekman explored global emotional expressions.
• Industrialized countries displayed similarities.
• To eliminate cultural learning, the Fore of New Guinea, an isolated culture, was examined.
• Participants showed expressions while considering different events.
• Ekman proposed six "basic emotions" based on the similarities comparing Western expressions and Fore expressions.

Sex Differences

• Evolutionary psychology expects males and females to be alike in adaptation domains.
• Expect sex differences when sexes face varying adaptive problems

Sex Difference Examples

• Different adaptive problems arise between men and women which cause Sex Differences such as ones in Aggression
• Also Sex Differences in Jealousy and Desire for Sexual Variety plus Mate Preferences.

Sex differences in Aggression

• Between 1965-1980, 86% of murderers were men.
• Access to females limits male reproduction.
• Effective polygyny is when few males have the most offspring.
• Sexual dimorphism entails different sizes and structures (Elephant seals).
• Humans display mild sexual dimorphism.
• Males are 12% larger than females.

Sex differences in Jealousy

• Imagining a partner's emotional attachment or sexual intercourse causes distress.
• The double-shot explanation is that Women think that if they are emotionally involved it will also be physical.
• However research indicates that the double-shot hypothesis does not explain the difference.

Sexual Variety Desire

• Desired sexual partners over a lifetime differs by sex.
• For men it's 18 partners in their lifetime worldwide.
• For women it's 4-5 partners in their lifetime worldwide.

Mate Preferences

• What is ranked highest by males is physical attractiveness based on studies performed on college students.
• Female college students prioritize earning potential more so than their male counterparts.
• Personality ranks high across the board, and both men and women value kindness plus excitement in their romantic partners.

Individual Differences

• The most challenging analysis level for evolutionary psychologists.
• Individual differences have three evolutionary perspectives.
• These entail environmental triggers of individual differences like heritable individual differences in addition to frequency-dependent strategic differences.

Big Five Personality Traits

• Big Five personality traits cluster key features of others' "adaptive landscape".
• Humans developed "difference-detecting mechanisms" to notice individual differences used to solving adaptive problems.

Evolutionary Psychology Limits

• Adaptations take time to forge.
• Precise selective forces on humans cannot be determined with certainty.
• This limitation requires inferences.
• Current mechanisms offer windows into the past.
• Learning about evolved mechanisms aids in overcoming ancestral environment limits.
• Evolutionary scientists still only scratched the surface regarding mechanisms' nature, details, and design.
• Modern conditions differ from ancestral ones where past adaptations might not suit today's environment
• Evolutionary hypotheses must not be easy, should be testable where conclusions can be drawn for true science.

Evolutionary Psychology Summary

• Selection drives evolution and changes species.
• Variants with greater genetic replication will take over.
• Evolutionary psychology has adaptations which entail the three premises, those being domain-specific, numerous, and functional
• Evolutionary psychology has deductive analysis in addition to an inductive analysis.
• Evolutionary psychology analyzes human nature plus sex and individual differences.
• The limitations of evolutionary psychology entail useful analyses of personality, humanity plus its sex and individual differences.