John D. Palmer has done research on the 6-hour tidal rhythm impressed on inter-tidal creatures exposed to successive drying and wetting cycles. He has shown that these tidal rhythms persist in organisms taken far from their feeding grounds and kept in constant light in another time zone. But even with this independent six hour rhythm before his eyes he sees nature running on a single circadian clock. Accordingly, he calls his recent book The Living Clock, in the singular. For him there’s one circadian timepiece, like the clock on the wall. It has designed into it various escapement mechanisms, like the second, minute and hour hands on a spring wound wristwatch. All rhythms are shaped by these escapement mechanisms. He speculates that “when the escapement mechanism is finally deciphered, a Nobel Prize should be the reward for the discoverer(s).” Again he uses the definite article, as if there was one gear train distributing the various units of the one 24 hour clock. Why not several escapements attached to several clocks, each originally coupled to a natural rhythm that got woven into the evolutionary process? Mightn’t these independent clocks establish relatively stable phase relations to each other? Even though core temperature, salt balance, urinary electrolytes, melatonin and other physiological functions are considered to follow a circadian rhythm, don’t they reach their peaks and troughs at different hours of the day or night? Perhaps inside the day they have their own ultradian ups and downs regulated by their own clock genes. These peaks and valleys and their timed relationships to each other must serve a biological purpose. Biological clocks moving in a variety of frequencies, controlled by genes that start and stop the enzymes in their separate reactions, could adjust to each other without a master clock controlling them all. Reaction products from successive rhythmic processes could become the starting ingredients for the next reaction in a biochemical cascade. These possibilities have been explored in an interesting recent research article, (with excellent bibliography,) by Tauber, Last, Olive and Kyriacou, who tie biological rhythms to clock genes and trace their divergences over evolutionary time.
"Changing: on the Biodynamics of Moral Courage"