Rhythms of Life: The Biological Clocks that Control the Daily Lives of Every Living Thing
Russell G. Foster
Format: PDF / Kindle (mobi) / ePub
Why can’t teenagers get out of bed in the morning? How do bees tell the time? Why do some plants open and close their flowers at the same time each day? Why do so many people suffer the misery of jet lag? In this fascinating book, Russell Foster and Leon Kreitzman explain the significance of the biological clock, showing how it has played an essential role in evolution and why it continues to play a vitally important role in all living organisms.
The authors tell us that biological clocks are embedded in our genes and reset at sunrise and sunset each day to link astronomical time with an organism’s internal time. They discuss how scientists are working out the clockwork mechanisms and what governs them, and they describe how organisms measure different intervals of time, how they are adapted to various cycles, and how light coordinates the time within to the external world. They review problems that can be caused by malfunctioning biological clocks—including jet lag, seasonal affective disorder, and depression. And they warn that although new drugs are being promoted to allow us to stay awake for longer periods, a 24/7 lifestyle can have a harmful impact on our health, both as individuals and as a society.
C., Goldstein, R. & Volicer, L. (2001) Differential circadian rhythm disturbances in men with Alzheimer disease and frontotemporal degeneration. Arch Gen Psychiatry, 58, 353–60. Hastings, J. W. (2001) Fifty years of fun. J Biol Rhythms, 16, 5–18. Hastings, J. W. & Sweeney, B. M. (1958) A persistent diurnal rhythm on luminescence in Gonyaulax polyedra. Biol Bull, 115, 440–458. Hattar, S., Lucas, R. J., Mrosovsky, N., Thompson, S., Douglas, R. H., Hankins, M. W., Lem, J., Biel, M., Hofmann, F.,
to the tuft containing the light-sensitive rod and cone photoreceptors and the inner part of the carpet, the weave, containing the cells that process the light information from the rods and cones. Rods are typically associated with vision in dim light and cones with colour vision in bright light. Information passes from the retina to the brain through the retinal ganglion cells whose projections form the optic nerve (Foster & Hankins, 2002) (Figure 6.2). The master clock in mammals, the
million years ago. If we look back beyond that, before the animal branch of the evolutionary tree, and examine the molecular basis of the clock in plants, fungi or even photosynthetic bacteria, what degree of conservation will we find in our even more ancient cousins? The answer is: not a lot. Detailed studies on the fungus Neurospora have identified several genes (frequency, white collar-1 and white collar-2) that have been shown to be critical for the generation of circadian rhythms. However,
living organisms is to look ahead, to produce future’ (Jacob, 1994). Animals produce future most dramatically by anticipating seasonal processes, and regulate their annual breeding, migration and hibernation to chime with them. Historically much of our understanding of biological clocks has arisen because of our attempts to understand how they do it. In a humbling sense, the scientists who study these events continue a line of enquiry that is older than the Upper Palaeolithic cave paintings in
the sleep phase (Figure 11.2A). This is opposed by what has been described as a ‘homeostatic drive for sleep’. The homeostatic drive describes an intuitive process whereby the drive for sleep increases the longer an individual has been awake (Figure 11.2B). These two processes interact to consolidate sleep (Figure 11.2C). In Dement’s words, ‘the push and pull of these opposing processes allows us to stay up all day and sleep all night’ (Dement & Vaughan, 1999). Homeostasis maintains the duration