The Price Equation
A mathematical identity partitions change in trait frequency into selection and transmission effects.
The Mechanism: The Price equation relates changes in a trait's average value to its covariance with reproductive success and to changes during transmission. It can be applied across levels and contexts, but it does not by itself specify the biological mechanism.
The Philosophical Pivot: A compact equation can clarify the structure of a change while leaving its causes open to investigation. Mathematical elegance is not the same as a complete explanation.
The Horizon: Researchers can use the equation to connect selection with inheritance in biological and cultural settings. The interpretation depends on what counts as a trait, an entity, and a measure of success.
The equation is an accounting framework, not a proof that every form of change is adaptation or that genes alone drive evolution.
A formula can show where to look next without telling us what the world means.
An equation can organize an explanation without completing one.
When I see a mathematical account of change, what assumptions about what is being counted should I inspect?