Citation
The Genetical Evolution of Social Behaviour
TL;DR
Genes can propagate through relatives, not just direct offspring (inclusive fitness)
Hamilton's kin selection theory provides the foundational explanation for why organisms sacrifice for relatives - a key puzzle in explaining alarm calling behavior. The theory introduces inclusive fitness, showing that genes can propagate not just through direct offspring but through relatives who share those genes.
Hamilton's rule (benefit × relatedness > cost) predicts when altruistic behaviors like alarm calling will evolve. This mathematical framework explains why prairie dogs in kin groups call despite personal risk, and why alarm calling is more common in species living with relatives.
Key Findings from Hamilton (1964)
- Genes can propagate through relatives, not just direct offspring (inclusive fitness)
- Altruism evolves when: benefit to recipient × relatedness > cost to caller
- Explains alarm calling in kin groups where individuals protect relatives