A Survey on Biological Rhythms

Abstract

The recurrence of any event within a biological system at more-or-less regular intervals can be considered a biological rhythm (Kalmus, 1935). The notion of a rhythm is sufficiently vague (i.e., not defined in physical terms) to be useful in listing a wide variety of phenomena that might reflect quite different underlying mechanisms. In the attempt to classify rhythms, restrictive descriptions become necessary that depend on the criteria chosen. Rhythms may be distinguished according to (1) a characteristic such as frequency; (2) the biological system (e.g., a population) in which the rhythm is observed; (3) the kind of process that generates the rhythm; or (4) the function that the rhythm fulfills. Some of these aspects are briefly touched upon in the following paragraphs.