The torpor switch: a bistable flip with hysteresis

Is euthermia↔torpor a discrete flip or a smooth dial? Ramping the torpor drive DOWN holds the euthermic branch until −h_sp then JUMPS to torpor (at -0.6500); ramping back UP holds torpor until +h_sp then jumps back (at 0.6500). The hysteresis loop has width 1.3000 — a bistable SWITCH.

RH1, the package's central question. A hysteresis loop of width ~2·|h_sp| with discontinuous jumps is the signature of bistability: torpor is a state the loop FLIPS into, not a metabolic rate it slides down. Mechanism [V]; the drive threshold is [L]; the absolute metabolic-rate drop is [O].

The hysteresis loop

The down-jump and up-jump occur at opposite-signed drives (-0.6500 and 0.6500), so the system shows a loop of width 1.3000 — positive (True), which by definition means two stable states coexist over a range of drives. That is a switch, not a dial (True).

Why this is the right framing for hibernation

A deep hibernator does not gently lower its rate; it commits to a distinct low-metabolic STATE and later commits back. Hysteresis explains why interbout arousals are abrupt and why the transition resists small perturbations -- the opposite basin has to disappear before the flip happens.

The cross-species twist

If torpor is a switch, the next question is whether the switch is BUILT INTO the human genome (present but silenced) or absent. The bear-vs-human chapter answers it from the measured panel.