Development can involve substantial material, structural, and functional transformation. Molecules are replaced, cells divide and die, tissues reorganise, functions change, and organism–environment relations may shift through time.
Where a living system remains organisationally continuous through such transformations, that continuity does not require preservation of the same material components, structures, or developmental states. Organised persistence and material sameness are therefore distinct.
This distinction is important for developmental explanation. A developing organism may remain continuous despite extensive change, but that continuity should not be assumed merely because development is occurring. The explanatory task is to establish what organisation persists or is re-established and which materially realised dependencies enable that continuity in the case concerned.
Development should therefore not be identified with organised persistence itself. Development describes biological transformation through time; organised persistence concerns the further question of whether and how relevant organisation continues through that transformation.
This is why developmental identity cannot be reduced to fixed structures, genetic templates, or static forms. Where developmental identity is maintained across change, its basis must be sought in the organisation and dependencies that warrant treating the changing system as continuous rather than in material sameness alone.
Key point: organised persistence may occur across substantial developmental transformation, but its presence and enabling dependencies must be established rather than built into the definition of development.