Complexity does not scale by staying whole.
A living system becomes capable by becoming differentiated.
Cells specialize. Organs separate. Neural pathways multiply. Redundancy absorbs shocks. Different parts perform different work under different conditions.
Development does not preserve every neuron it creates. The nervous system produces excess capacity, tests connections, and removes cells that do not secure the support required to survive.
The apparent excess is not incompetence.
It is optionality under selection.
A body is not resilient because every cell does everything.
It is resilient because millions of specialized parts remain distinct while serving one organism.
Nature does not eliminate seams. It governs them.