“We have been aware of circadian rhythms for thousands of years without realizing what they were, how they worked, or how crucial they are for our health and well-being. In the 4th century bc, Androsthenes, one of Alexander the Great’s sea captains, described the daily leaf movements of the tamarind tree (Tamarindus indicus), as they curled and uncurled. The medical pioneers Hippocrates and Galen noted the periodic 24-hour rhythmicity associated with fever. But although many observations were made throughout the centuries, indicating that plants and animals carry out their activities in regularly timed 24-hour cycles, these were no more than interesting facts of nature. What began to change this view was a remarkably simple biological experiment published in 1729 by a French astronomer, Jean Jacques d’Ortous de Mairan. De Mairan knew that a mimosa plant (probably Mimosa pudica) was a heliotrope, turning towards the sun in daylight; but as well as being sensitive to the sun’s position it was sensitive in another way—its leaves would droop at dusk and rise during the day. De Mairan put a mimosa plant in a cupboard to see what happened when it was kept in the dark. He peeked in at various times and observed that its leaves still opened and closed rhythmically—rhythmically—it was as though it had its own representation of day and night. The plant’s leaves still drooped when the plant considered it to be night (subjective night) and rose up during the plant’s subjective day. He had unwittingly shown that the plant had an endogenous rhythm which persisted under constant conditions; in effect it had its own internal biological clock. It took another 230 years to come up with the term to label this rhythm and nearly as long for the endogenous nature of such rhythms to be finally accepted.”
The Rhythms Of Life: The Biological Clocks That Control the Daily Lives of Every Living Thing by the same authors
Popular science at its most exciting: the breaking new world of chronobiology – understanding the rhythm of life in humans and all plants and animals. The entire natural world is full of rhythms. The early bird catches the worm -and migrates to an internal calendar. Dormice hibernate away the winter. Plants open and close their flowers at the same hour each day. Bees search out nectar-rich flowers day after day. There are cicadas that can breed for only two weeks every 17 years. And in humans: why are people who work anti-social shifts more illness prone and die younger? What is jet-lag and can anything help? Why do teenagers refuse to get up in the morning, and are the rest of us really ‘larks’ or ‘owls’? Why are most people born (and die) between 3am-5am? And should patients be given medicines (and operations) at set times of day, because the body reacts so differently in the morning, evening and at night? The answers lie in our biological clocks the mechanisms which give order to all living things. They impose a structure that enables us to change our behaviour in relation to the time of day, month or year. They are reset at sunrise and sunset each day to link astronomical time with an organism’s internal time.
Monkeys are made of chocolate by Jack Ewing
Discover the mysterious and fascinating ways in which animals and plants—and people—interact with one another in the rainforests of Costa Rica. Author and naturalist Jack Ewing shares a wealth of observations and experiences, gathered from more than three decades of living in southwestern Costa Rica, home to some of the most prolific and diverse ecosystems on Earth. More than just a simple collection of essays, Monkeys are Made of Chocolate is a testament to the wonder of life in all its countless guises, as seen through the eyes of a man with a gift for subtle discernment and a natural flair for storytelling.
Especially the chapter Moon Lore: Method, Magic or Madness