Biological Sciences
Evolution
1964
AdvancedHamilton's Rule
Altruistic behavior evolves when benefit × relatedness exceeds cost.
By W.D. Hamilton
Biological Sciences
Hamilton's Rule
1964 · W.D. Hamilton
Why it matters: Unified genetics and social behavior—foundation of sociobiology.
Discoverers: W.D. Hamilton (1964)
What does it mean?
Altruistic behavior evolves when benefit × relatedness exceeds cost.
Why should I care?
Unified genetics and social behavior—foundation of sociobiology.
Variables & Units
| Symbol | Name | Unit | Meaning |
|---|---|---|---|
| Relatedness | — | Genetic relatedness coefficient | |
| Benefit | — | Fitness benefit to recipient | |
| Cost | — | Fitness cost to actor |
Worked Example
Helping sibling (r=0.5) worth it if benefit > 2× cost.
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Altruistic behavior evolves when benefit × relatedness exceeds cost.
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