Are you a Lark or an Owl? That is the question? asked by Teignmouth Probus Club’s returning guest speaker Dr. Roger Avery, a retired Senior Lecturer in Zoology at Bristol University. “Biological Clocks” was the subject of his illustrated talk. The concept now called the Circadian Rhythm was first observed by a French Astronomer Jean-Jacque d’Ortous de Mairan in 1729 when studying the Mimosa pudica, a light sensitive plant which opened its leaves at dawn and closed them at dusk on a 24 hour cycle. This phenomenon continued when no light was provided but still continued in permanent darkness in time with daily rotation of the earth. Our speaker also studied a single cell green algae in the river Avon in Bristol which also had a regular daily life cycle but controlled by the tide. When a specimen was taken to the lab in non-tidal location, the cycle of photosynthesis on rising tide and dropping into the mud at low tide also continued for several days. The Human Circadian Rhythm was demonstrated bases on ‘average’ data but there was also a clear pattern that people fall into two main categories, early risers and best in the mornings or late to bed afternoon performers. The ways people respond to ‘jet-lag’  or shift workers and Seasonal Affected Disorder (SAD) suffers were other examples consequent upon the interruption or interference of the circadian rhythm.

Until quite recently (2017) why/how these biological clocks worked from the simplest of organisms to the most complex remained a bit if a mystery. A particularly instance was how Arctic Terns managed to migrate between the N/S poles and vice versa at regular times every year.  A team of scientists were rewarded with the Nobel Prize in Physiology or Medicine for their research of molecular mechanisms controlling circadian rhythms. Our speaker enthralled the meeting with nature’s amazing ‘ESP’ feats and some of the discoveries of ‘how they do it’.    

An appreciative vote of thanks was given by past Chairman members Bruce Watt.

Posted by Press Officer Rick Purnell