The gene criterion: a present, drivable effector-command pair
The gene-level criterion is NOT a γ value. Across the panel the endotherms all carry a drivable thermogenic effector-command pair -- a furnace (UCP1) plus a sympathetic command (ADRB3) -- while in both ectotherms queried the ADRB3 command does not resolve to a genomic ortholog. Presence of the drivable pair, observed not assumed, is the criterion.
A measured cross-species panel (UCP1 furnace, ADRB3 command, PDK4 fuel-switch; human, mouse, rat, pig, ground squirrel, zebrafish, frog) shows the command gene present across endotherms and absent in the ectotherms queried. The deeper criterion is the DYNAMICS -- a defended attractor -- because where the furnace is silenced (pig pseudogene) the endotherm still defends by other routes.
The panel (measured, offline-reproducible)
Every γ below is a real promoter read fetched through the DNA pipeline (nearest-neighbour stacking energy, SantaLucia 1998, window TSS−2000..+500) and cached so it re-derives offline bit-for-bit (True).
| species | class | UCP1 γ | ADRB3 γ | PDK4 γ | command pair? |
|---|---|---|---|---|---|
| Danio rerio | ectotherm | 1.2206 | absent | 1.1727 | no |
| Xenopus tropicalis | ectotherm | 1.2644 | absent | 1.4072 | no |
| Cavia porcellus | endotherm | 1.4176 | 1.4942 | 1.3816 | yes |
| Homo sapiens | endotherm | 1.4054 | 1.4462 | 1.4112 | yes |
| Ictidomys tridecemlineatus | endotherm | 1.4029 | 1.3806 | 1.3647 | yes |
| Marmota marmota | endotherm | 1.4156 | 1.3867 | 1.3702 | yes |
| Mesocricetus auratus | endotherm | 1.4264 | 1.3606 | 1.3934 | yes |
| Microcebus murinus | endotherm | 1.4255 | 1.4078 | 1.3976 | yes |
| Mus musculus | endotherm | 1.4124 | 1.3502 | 1.4049 | yes |
| Oryctolagus cuniculus | endotherm | 1.4144 | 1.4976 | 1.4965 | yes |
| Rattus norvegicus | endotherm | 1.4273 | 1.4068 | 1.4083 | yes |
| Sus scrofa | endotherm | 1.3951 | 1.4180 | 1.3595 | yes |
| Urocitellus parryii | endotherm | 1.4178 | 1.4022 | 1.3762 | yes |
| Ursus americanus | endotherm | 1.4415 | 1.4525 | 1.3675 | yes |
The criterion, stated
Endotherms have the drivable {UCP1 furnace + ADRB3 command} pair: True. The ectotherms queried lack the ADRB3 command (no ortholog resolves): True. The criterion is a PRESENT, drivable effector-command pair -- a structural fact about the genome, read by presence, not a number on the γ scale.
Why the deeper criterion is the dynamics
The pig is an endotherm whose UCP1 is a pseudogene, yet it still defends its setpoint by other routes. So the single furnace gene is neither necessary nor a γ threshold; the robust criterion is the DEFENDED ATTRACTOR itself, which the R19 loop captures directly. Two explicit NULLs make this firewall concrete (next chapter and the bear-vs-human chapter).
Grades
Gene presence is [L] cited and observed (auditable accessions). The strong 'command absent across all ectotherms' claim is [O] -- symbol orthology across distant taxa is itself uncertain; the queried-assembly observation is [L].