PSY2020/L01/01 Mon Feb 17 12:05:00 GMT 2025

Lecture 4: Kin Selection, Cooperation, and Parental Investment

Introduction

• Focus on kin selection, cooperation, and parental investment in the context of sociality.

• Discussion of cooperative behaviors between kin and the significance of this in the context of social behavior.

Workshop Information

• Previous workshop was beneficial for exam preparation.

• Upcoming workshop on February 27, focusing on an alternative essay style and practical skills from Lecture 2.

• Peer review of example essays will occur.

Overview of Sociality

• Sociality is a complex phenomenon with several contributing factors.

• Discussion on themes of cooperation and altruism, referencing previous lectures.

  • Altruism is controversial; it often arises from kinship and cooperation dynamics.

Costs and Benefits of Behavior

• Simplified understanding of behavior through cost-benefit analysis:

  • Cooperation: Beneficial for both parties.

  • Altruism: Costs to the self for the benefit of others.

  • Selfishness: Individual benefit potentially leading to competition.

  • Punishment and Aggression: Arise when both parties incur costs.

Examples of Cooperation in Animals

• Eusocial Insects: Such as honeybees, with single breeding queen and sterile worker bees (altruistic behavior).

• Cooperative Vigilance: Seen in meerkats for predator detection.

• Cooperative Hunting: Example with African wild dogs.

• Kin often cluster together in groups leading to increased cooperation.

Evidence of Cooperative Behavior

• Non-Human Primates: Grooming often occurs more between kin than non-kin; serves as social glue.

• Reciprocal Behaviors and Coalition Formation: Group behaviors for defense.

• Cooperative Breeding: Notably in common marmosets where non-breeding females help rear the dominant female's young.

The Concept of Altruism

• Altruism defined as acts that benefit others at a cost to the actor.

• The evolution of such behavior is complex, often tied to kin selection and the benefits to genetic success.

Understanding Kin Selection and Inclusive Fitness

• Hamilton's Theory: Builds upon Darwin's theory of natural selection by introducing the idea of indirect fitness through kin.

  • Inclusive Fitness: Child's fitness combined with the indirect fitness through siblings.

  • Coefficient of Relatedness (r): Probability of shared alleles among kin.

Hamilton's Rule of Kin Selection

• Altruistic behaviors favored when Benefit (B) exceeds Cost (C) weighted by relatedness (r).

• Formulated as:

  • rB > C (or equivalently B/C > 1/r).

• Importance of recognizing kin to maximize inclusive fitness.

Mechanisms for Kin Recognition

• Not solely based on appearance; olfactory cues can play important roles in identifying kin.

• Imprinting: Mechanisms observed in various species for recognizing relatives (e.g., Lorenz's work with ducklings).

Brood Parasites - A Case Study: Cuckoos

• Cuckoos lay eggs in the nests of other birds, leading to kin recognition failures.

• Explains how broods can be compromised if recognition mechanisms fail.

Research Study - Chimpanzees and Kin Recognition

• Research indicates differences in recognition abilities between mothers and offspring in chimpanzees, often influenced by visual and environmental factors.

Parental Investment: Theories and Types

• Trivers' Definition: Investment in offspring enhances survival at a cost to the parent's ability to breed again.

• Different forms include feeding and protection during critical juvenile stages in birds and fish.

• Differences in gamete size between males and females define some aspects of parental investment strategies.

Variance in Reproductive Success

• Bateman's Principle highlights the variance of reproductive success among genders due to physiological constraints.

  • Males can generally achieve higher reproductive success through mating with multiple partners.

Conclusion on Parental Investment Dynamics

• Parental care also involves strategic decisions based on fitness benefit considerations.

• Conflicts can arise within family units regarding care and investment strategies.

Final Remarks and Future Topics

• Will continue discussions on parental investment dynamics and strategies in future lectures.

• Wrap-up with additional recommended readings to deepen understanding of discussed concepts.