Hamilton meets causal decision theory.

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Theoretical Biology

Background:

• The evolution of altruism is a central topic in evolutionary biology.
• Two primary mathematical frameworks, inclusive fitness and direct fitness, are used to model kin selection.
• A common assumption is that these models are equivalent representations of the same evolutionary process.

Purpose of the Study:

• To contrast the inclusive fitness and direct fitness approaches to modeling altruism.
• To critically evaluate the causal interpretation of the direct fitness approach.
• To determine which framework provides a more unambiguous causal partition of variables in altruism evolution.

Main Methods:

• Comparative analysis of inclusive fitness and direct fitness models.
• Application of an analogy between inclusive fitness theory and causal decision theory.
• Examination of causal interpretations of variables within each modeling framework.

Main Results:

• The consensus view of inclusive fitness and direct fitness as equivalent is challenged.
• A fundamental ambiguity exists in the causal interpretation of the direct fitness approach.
• The inclusive fitness framework provides a clear and unambiguous causal partition of relevant variables.

Conclusions:

• Inclusive fitness theory offers a superior causal framework for understanding the evolution of altruism.
• Direct fitness models, despite mathematical equivalence, suffer from causal ambiguity.
• This work clarifies the distinct causal underpinnings of different kin selection modeling approaches.