Why kin and group selection models may not be enough to explain human other-regarding behaviour

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Game Theory

Background:

• Traditional kin and group selection models focus on single fitness transfer scenarios.
• Phenotypes in these models are binary: either make a fitness transfer or not.
• Hamilton's rule predicts phenotype spread based on a given fitness transfer.

Purpose of the Study:

• To generalize kin and group selection models to accommodate varied fitness transfer possibilities across individuals or generations.
• To investigate the nature of phenotypes (preference relations) that can be explained by these generalized models.
• To identify implications for testing hierarchical selection models.

Main Methods:

• Developed a generalized framework for kin and group selection incorporating diverse fitness transfer scenarios.
• Defined phenotypes as preference relations specifying behavior across a range of fitness transfers.
• Analyzed the mathematical conditions under which preference relations are explained by kin and group selection.

Main Results:

• Only preference relations linear in fitnesses can be explained by kin selection models in the generalized setup.
• A similar limitation (linearity in fitnesses) applies to a broad class of group selection models.
• This finding offers a potential method to falsify hierarchical selection models, irrespective of relatedness or assortativeness.

Conclusions:

• Generalized kin and group selection models necessitate linear preference relations for evolutionary explanation.
• The findings provide a novel, potentially falsifiable prediction for hierarchical selection theories.
• Empirical evidence in humans suggests hierarchical selection models alone are insufficient to account for other-regarding behaviors.