Evolutionary Perspectives of Emotion

Evolutionary Perspectives of Emotion

Introduction to Animal Emotions

  • Questions posed:

    • Does a snake have emotions?

    • How about a pigeon? A mouse? A housecat? A dog? A chimpanzee?

  • Reference to Charles Darwin (1872):

    • Emphasized parallels in emotional expressions between animals, infants, and adult humans.

    • Suggested that emotional expressions are part of our evolutionary heritage.

Functional Adaptations of Emotion

  • Modern psychologists' view:

    • Emotions are functional adaptations, increasing survival and reproduction likelihood.

    • Historical premise: Individuals with emotions had a higher likelihood of passing genes compared to those without emotions, resulting in the spread of emotional genes throughout populations over time.

Background about Genes

Gregor Mendel and Genetic Inheritance

  • Hereditary units:

    • Genes are units of heredity maintaining structural identity across generations.

    • Each gene functions like a recipe detailing protein production necessary for bodily functions.

  • Chromosomal structure:

    • Genes are paired and aligned along chromosomes, which also come in pairs. Exception: Male mammals have unpaired X and Y chromosomes.

  • Gene Definition:

    • Historically defined as segments of chromosomes composed of double-stranded DNA.

  • Sexual reproduction:

    • Results in individuals receiving one half of genes from the mother and one half from the father.

  • Mutations: Occasional errors in gene copying, resulting in random changes in genetic information.

Fundamental Principles of Evolutionary Theory

Historical Context of Evolution

  • Darwin's initial understanding:

    • Lack of knowledge about genes; speculated on the inheritance of traits from parents to offspring.

  • Integration of Darwin and Mendel's theories:

    • 1920s-30s united Darwin’s ideas with Mendelian genetics.

    • The intersection of research on DNA forms the foundation of modern evolutionary theory.

Natural Selection Explained

  • Definition:

    • Natural selection is a mechanism where detrimental mutations diminish in a population while beneficial ones proliferate.

  • Beneficial mutations:

    • Lead to adaptations that enhance survivability and reproductive success, persisting in populations over time.

Functional Characteristics of Behaviors

Criteria for Gene-based Characteristics

  • Functional characteristics must:

    1. Increase survival probability to reproductive age.

    2. Enhance chances of producing more offspring that subsequently survive.

    3. Aid survival and reproductive success of one’s relatives.

  • Summary: From an evolutionary standpoint, a characteristic is deemed functional if it boosts gene representation in subsequent generations.

Differentiating Functionality from Adaptation

Understanding Adaptation and Functionality

  • Functionality:

    • A characteristic is functional if it contributes to greater gene representation in future generations.

  • Adaptation:

    • A characteristic advantageous in the past (in its Environment of Evolutionary Adaptedness - EEA) may not offer the same advantages presently.

  • EEA: The historical context influencing a characteristic's spread and effectiveness.

    • Example: Preference for fatty, sugary foods was functional in environments with food scarcity but may lead to health issues in modern societies with abundant resources.

Example of Non-functional Characteristics

  • Erected hair in mammals:

    • Significance: Instinctively intimidating to predators.

    • Human context: Less functional due to shorter, often covered arm and shoulder hairs.

    • Historical effect: Mechanism inherited from ancestors.

  • Emotion-related adaptations:

    • Traits like anxiety may have had adaptive functions in ancestral environments but pose challenges in contemporary contexts (e.g., stress).

Altruism in Evolutionary Context

Concept of Altruistic Behavior

  • Definition:

    • An altruistic act benefits others at a potential cost to the actor (individual).

  • Gene spread: Could a gene promote altruistic behavior to propagate species survival?

    • Nonhuman altruism is comparatively rarer; mechanisms inherited raise questions about origins and developments.

  • Examples of human altruism:

    • Charitable contributions.

    • Assisting distressed individuals or classmates.

    • Organ donation under life-threatening circumstances.

Intrapersonal Functions of Emotion

Impact on Individual Behavior

  • Intrapersonal functions: Benefit the individual experiencing the emotion by influencing:

    • Cognitive biases

    • Physiological states

    • Behavioral responses

  • Illustrative examples of negative emotions:

    • Fear: Triggers escape mechanisms from threats.

    • Anger: Facilitates reclaiming stolen resources.

    • Disgust: Prevents ingesting harmful substances (e.g., rotten food).

Interpersonal Functions of Emotion

Social Functions of Emotion

  • Human social behavior:

    • Humans are ultrasocial beings, functioning cooperatively in groups.

    • Emotion functions reinforce relationships, crucial for survival and genetic propagation.

  • Example - Love:

    • Commitment towards the well-being of others solidifies vital social connections (Fehr & Russell, 1991).

  • Negative emotions as social signals:

    • Embarrassment indicates awareness of a social error, encouraging trust and social acceptance from others.

Emotions as Functional Adaptations

Evolution of Emotional Responses

  • Fundamental definitions:

    • Emotions are seen as functional adaptations that emerged through natural selection processes.

  • Mechanisms of inheritance:

    • Genes facilitating emotional experiences originated as random early mutations.

    • Typically, emotionally capable individuals had higher offspring survival rates, promoting these genes' prevalence in the gene pool.

Understanding Emotions as Adaptations

Implications of Adaptations

  • Universal aspects of emotion:

    • Shared evolutionary heritage indicates similarities in emotions across cultures.

  • Common characteristics: Examples include physiological responses to fear, beneficial for any species that might be preyed upon.

  • Adaptational effectiveness: While a characteristic can be adaptive, it may not be universally applicable across all contexts or species.

Universal Nature of Emotions

Physiological Responding Across Cultures

  • Study by Levenson et al. (1992):

    • Investigated physiological responses to emotions among participants from the Minangkabau community in Indonesia versus USA adults.

    • Findings: No significant physiological response differences between groups during expressions of anger, fear, sadness, disgust, and happiness.

Evolutionary Role in Modern Emotion Theories

Emotional Signals and Decision-Making

  • The affect infusion model (Forgas, 1995):

    • Emotional feelings signal environmental evaluations, affecting judgments and decisions reflecting emotional valence.

    • Positive moods indicate safety; negative moods signal the need for caution and problem-solving.

  • Connections to Modern Theories:

    • Theoretical links to core affect and psychological construction theories of emotion, and relevance to Schachter-Singer theory.

Approach and Avoidance Motives in Evolution

  • Behavioral categories:

    • Gray (1982) suggested the mammalian brain is structured for approach (opportunities) and avoidance (threats).

  • Neuroscientific evidence:

    • Neurotransmitter differentiation (excitatory vs inhibitory) shapes behavioral responses to environmental cues.

Neural Programs and Emotional Processing

  • Superordinate neural programs:

    • Explain how interconnected emotional responses guide behavior through activation of specific brain networks.

    • Emotions coordinate multiple processing modules to effectively resolve situational challenges.

Phylogeny of Emotions

  • Evolutionary tree of emotions:

    • Nesse and Ellsworth (2009) argue for conceptualizing emotions as having a phylogeny that evolved in response to new selection pressures and environmental nuances.

  • Evolutionary progression:

    • Earliest emotions linked strictly to basic survival (food, threats).

    • As species evolved, emotional responses grew more complex to address varied environmental factors.

Bibliography and Reading Material

  • Shiota, M., Kalat, J.W. (2018). Emotion (3rd ed.). Oxford University Press. Chapter 2.