Structure-Function Inseparability: A Dual-Track Co-Evolutionary Account of Consciousness

Recursive Intelligence Theory (RIT) characterizes intelligence as a functional, level-dependent property that evolves through increasing regulatory depth. While this framework explains what intelligence is and how recursive regulation develops, it leaves open a deeper evolutionary question: under what conditions can such regulatory depth arise and stabilize at all? This paper introduces the principle of Dual-Track Co-Evolution (DTCE), according to which structural substrates and functional regulatory properties evolve through tightly coupled, recursively interacting dynamics. Evolutionary change may be initiated in either track without ontological priority, but sustained development occurs only when structural and functional configurations remain mutually compatible. DTCE rejects both strong emergence and reductionism, offering instead a constraint-based account in which intelligence evolves when functional innovation is matched by corresponding structural reorganization. This framework clarifies why intelligence is rare, discontinuous in appearance yet continuous in physical substrate, and why recursive regulation cannot be understood independently of the structures that support it.