The Biological significance of Circannual Rhythms in Animals and Humans

This presentation will first show examples of circannual rhythms within the animal kingdom and also give evidence for circannual rhythms in humans. A clear distinction must be made between „true“ circannual rhythms and „simple“ annual or seasonal rhythms. Although the biological significance probably is similar in both cases, the possible underlying mechanisms are very likely quite different. The biological importance lies in the fact that both circannual rhythms and seasonal rhythms allow physiological changes to be complete well in advance of seasonal environmental changes. Those environmental variables that,…