Ann Psychiatr Clin Neurosci | Volume 1, Issue 1 | Research Article | Open Access

Paleontology of Circadian Rhythm Disorders

William W Mc Daniel^*

Department of Veterans, Eastern Virginia Medical School, USA

^*Correspondance to: William W Mc Daniel 

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Abstract

The circadian cycle of humans and other mammals is close to one hour longer than the 24 hour period from sunrise to sunrise. It appears that all mammals examined have shown a circadian rhythm with cycle duration over 24 hours. Interestingly, birds show a circadian cycle of less than 24 hours, close to 23 hours. Terrestrial invertebrates, the insects provide the key to understanding this discrepancy. The earliest identifiably mammalian fossils are from the Permian era strata. Insect orders that first appeared in the Permian era include the hemiptera (bugs), orthoptera (crickets and grasshoppers’), and the neuroptera (lacewings), all of whose modern survivors show a circadian cycle longer than 24 hours in at least some stage of the life cycle. The insects whose ancestors first appeared in Mesozoic strata with the birds include hymenoptera (bees, wasps and ants) and lepidoptera (butterflies and moths). Their modern survivors, like the birds, demonstrate a circadian rhythm shorter than 24 hours. There is now evidence for two large meteorite impacts on Pangea near the end of the Permian era, one in Wilkes Land of Antarctica, and the other just west of Australia. The eastward movement of the Australian continent/plate and the southeastward movement of the Antarctic continent/plate indicate that those meteorites were moving eastwards, and struck the planet obliquely. Having done so, they might have imparted momentum to the planet’s rotation, and so accelerated it. This may mean that circadian rhythm disorders are the consequence of a change in the duration of the solar day due to a disaster, and that daytime lethargy and depression may have had adaptive value to the mammals who survived that disaster, and the hunters of the Mesozoic.

Citation:

Mc Daniel WW. Paleontology of Circadian Rhythm Disorders. Ann Psychiatr Clin Neurosci. 2018;1(1):1002.