Evolutionary Psychology of Social Behaviour

Evolutionary Psychology of Social Behavior

• Dr Aimilia Kallitsounaki (A.Kallitsounaki-836@kent.ac.uk)

Understanding Evolutionary Psychology

• Common Misconceptions: Some perceive evolutionary psychology as claiming human nature is inherently selfish and wicked. However, such perceptions may oversimplify the complexity of human nature. Discussion includes evidence from historical records and cultural practices suggesting the inherent potential for kindness and cooperation.

Social Behavior in Primates

• Types of Social Structures:

  • Pair-bonded groups: Example - Gibbons (1) female and multiple males or (1) male and multiple females (Gorillas).
  • Multi-male and Multi-female systems: Example - Macaques.
  • Fission-fusion societies: Humans and Chimpanzees, where group composition changes frequently.
  • Multilevel or Hierarchical societies: Example - Baboons.

• Role of Grooming: Crucial social function for primates, facilitating bonding and hierarchy establishment (Henzi & Barrett, 1999).

Social Behavior – Orangutans

• Characteristics:

  • Semi-solitary species; arboreal lifestyle, minimal natural predators (van Schaik et al., 2004).
  • High caloric requirements dictate social structure, resulting in temporary feeding aggregations.

• Social Interactions:

  • Adult males and adolescents are usually solitary.
  • Adult females with offspring; females have overlapping home ranges and tolerance among them.
  • Males will display aggression when encountering each other.

Evolutionary Insights from Orangutans

• Clues to Human Sociality: Fossils suggest early hominids lived in open, vulnerable environments, leading to social cooperation for survival (Workman & Reader, 2001).

Pros and Cons of Social Groups

• Benefits of Group Living:

  • Enhanced predator detection and defense.
  • Better resource access (food, water).
  • Opportunities for cooperation and social learning.
  • Reduced risk of infanticide.

• Constraints:

  • Resource competition, pathogen transmission, and individual cognitive capacities.

Survival of the Friendliest

• Morphological Signals: Changes in Homo sapiens indicate increased cooperative behavior:
  • Facial structure: Reduced brow ridge suggests less aggressive tendencies (Cieri et al., 2014).
  • 2D:4D digit ratio: Indicative of prenatal androgen exposure and social sensitivity.
  • Increased Oxytocin: Related to social bonding.

Theories of Social Behavior in Evolutionary Context

1. Kin Altruism/Inclusive Fitness (Hamilton, 1964)
2. Parental Investment (Trivers, 1972)
3. Parent-Offspring Conflict (Trivers, 1974)
4. Reciprocal Altruism (Trivers, 1971)

Kin Altruism - Inclusive Fitness Theory

• Definition: Actors show self-sacrificing behaviors for relatives when costs are lower than benefits (c < rb).

  • Formula Explained:
  • (c): Cost to the actor
  • (r): Coefficient of relatedness
  • (b): Benefit to the recipient

• Real-Life Applications: Example of Pilgrim Fathers, survival linked to kin support (McCullogh & York Barton, 1991).

• Research Studies: Here, kinship influenced altruistic behaviors among participants manipulated by recipient characteristics (Burnstein et al., 1994).

Parental Investment & Family Life

• Definition: Investment that increases an offspring's survival chances at the parent's expense (Trivers, 1972).

• K-Selection: Humans classify as K-selected with high parental care, enhancing inclusive fitness (Drickamer & Vessey, 1992).

• Grandmother Hypothesis: Evidence suggests grandparental investment in grandchildren purposes social structure and enhances offspring survival (Pelham, 2019).

Parent-Offspring Conflict

• Definition: Conflicts arise over resource allocation and reproductive decisions predicted by evolutionary theory (Trivers).

Reciprocal Altruism

• Prerequisites:

  • Cost of altruistic act to the actor must be less than the benefit to the recipient.
  • Ability to recognize individuals for reciprocation.
  • Extended lifespan to encounter individuals multiple times.

• Equally Important Behaviors: Reciprocal altruism extends beyond kinship, crucial in human societies.

Case Studies on Reciprocal Altruism

• Aché Tribe: Practices shared paternity and food sharing.
• Yanomamö: Notable for both trade practices and violent inter-group relations showing complex social dynamics.

Non-Reciprocal Acts of Altruism

• Example: Blood donation - an instance raising questions about pure altruism.

In-Group Loyalty and Out-Group Hostility

• Group Dynamics: Essential for group identity and tribal mobilization (Wilson, 1973).
  • Conflict factors—Robbers Cave Experiment illustrates how group identities form and escalate aggression.

Conclusion

• Human sociality is complex, shaped significantly by evolutionary forces, indicating our distinct behaviors and societal structures are a product of millions of years of interaction, cooperation, and social evolution.