Figure 18

From homeostasis to clocks and chronomes. †Inferential statistical methods map chronomes as molecular biology maps genomes; biologic chronomes await resolution of their interactions in us and around us, e.g., with magnetic storms in the interplanetary magnetic field (IMF). The alignment of spectra – data transpositions from the time into the frequency domain of data series recorded on us and around us – has just begun and requires lifetime monitoring for critical variables that may provide the reference values for preventive health and environmental care. Homeostasis recognizes that physiological processes remain largely within relatively narrow (but hardly negligible) ranges in health and that departure from such normal ranges is associated with overt disease and still serves that purpose. But it can be improved upon in replacing time-unqualified ranges by time-varying reference limits as prediction and tolerance intervals (chronodesms). Most important, however, is that variability within the normal range is not dealt with as if it were random. The body strives for structured variation, not for "constancy". Learning about the rules of trends and further about rhythmic and chaotic variations that take place within the "usual value ranges" is not needed for the postulation of a "biological clock" that would enable the body to keep track of time. Not surprisingly, this restriction in the scope of chronobiology is most welcome to all of those who still wish no more than their normal ranges and usually only time-unspecified "baselines". The fact that single cells and bacteria are genetically coded for a spectrum of rhythmic variation indicates, however, that the concept of "clock" needs extension beyond the year as a calendar and beyond the beating trans-year, [8, 171] and today beyond the recording in the experimental laboratory of lighting, temperature and feeding, among other obvious conditions. Magnetic storms must not be ignored [310–312]. There is a further need to extend focus beyond circadians. When the giant alga Acetabularia, a prominent model for scholars interested in the mechanism of a "clock", is placed into continuous light, after some days in light and darkness alternating every 12 hours (!), the spectrum of changes in its electrical potential reveals the largest amplitude for a component of about (no precisely!) 1 week rather than for one of about 24 hours. An Acetabularia population also shows a circadecadal rhythm [313]. The concept of a broad chronome takes the view that changes occurring within the usual value range resolvable as chronomes, with a predictable multifrequency rhythmic element, allow us to measure the essence of the dynamics of everyday life, and are essential to obtain warnings before the fait accompli of disease, Fig. 16 so that prophylactic measures can be instituted in a timely way.