Note this quote from "Homeostasis" , Langley
Man exhibit many circadian rhythms. He sleeps at about the
same time each day; his temp fluctuates a degree or two in a
daily pattern; the eosinophil count in his blood rises and
falls; urine output and composition also vary rhythmically
as do other functions.
Under natural conditions the circadian period is
synchronized with the period of the earth's rotation by
means of various inputes from the environment.
The day-night changes in illumination and temperature seem
to be the most important factors."
If not temperature moderation, then what 'just so' story
explains all the above?
Energy moderation with modification through descent.