Natural Selection and Drift as Individual-Level Causes of Evolution

Area of Science:

• Philosophy of Science
• Evolutionary Biology

Background:

• Reisman and Forber (2005) argued that evolutionary drift and natural selection are population-level causes of evolution, based on the manipulation condition.
• The manipulation condition is considered an important, yet insufficient, criterion for identifying causes of evolutionary change.

Purpose of the Study:

• To critically evaluate Reisman and Forber's arguments regarding population-level causes of evolution.
• To introduce and apply the criterion of invariance to causal explanations in evolutionary biology.

Main Methods:

• Critically analyze Reisman and Forber's manipulation condition using an example of evolutionary drift.
• Incorporate Woodward's criterion of invariance into causal explanations.
• Examine the level of causation (individual vs. population) for drift and natural selection.

Main Results:

• The manipulation condition alone is insufficient for determining the level of evolutionary causation.
• When invariance is considered alongside the manipulation condition, evolutionary drift is often better understood as an individual-level cause.
• Natural selection and drift can be considered population-level causes under specific conditions, such as genuinely indeterministic events or frequency-dependent selection.

Conclusions:

• Causal explanations in evolutionary biology require more than the manipulation condition; invariance is a critical parameter.
• The level of causation for evolutionary processes like drift depends on the specific criteria applied.
• A nuanced understanding of evolutionary causation acknowledges both individual- and population-level influences.