On the hodological criterion for homology

Area of Science:

• Evolutionary Biology
• Developmental Biology
• Neuroscience

Background:

• Defining homology, or "sameness" of traits across species, presents a persistent challenge.
• Current gene-centered criteria for homology stem from reductionist views, often conflicting with empirical data.
• An organismic-epigenetic perspective views organisms as dynamic systems, necessitating context-dependent homology assessment.

Purpose of the Study:

• To critique the prevailing gene-expression criterion for homology.
• To propose an alternative framework for determining homology based on an organismic-epigenetic viewpoint.
• To advocate for the hodological criterion in assessing homology of neural structures.

Main Methods:

• Comparative analysis of historical and current homology definitions.
• Conceptual critique of reductionist vs. organismic-epigenetic frameworks.
• Argument for context-dependent homology criteria.

Main Results:

• The concept of absolute homology criteria is challenged.
• Gene expression is shown to be an insufficient universal criterion for homology.
• The hodological criterion (neural connectivity) is proposed as superior for brain homologies.

Conclusions:

• Homology determination requires context-specific criteria, varying with the trait and developmental stage.
• An organismic-epigenetic approach offers a more robust framework for understanding homology.
• Neural connectivity provides a reliable basis for comparing homologous brain structures.