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Foster and Kreitzman - Seasons of Life - Cockroaches

Identifier

020329

Type of Spiritual Experience

Background

A description of the experience

Seasons of Life – Russell G Foster and Leon Kreitzman

If the lights are left off and the cockroach is …... kept in constant darkness, there is a bunching of activity into a 2 to 3 hour period that recurs roughly every 24 hours.  The pattern repeats itself day after day after day.  Even in the constant conditions of darkness, the cockroach is able to divide time into a subjective 'day' and 'night', and anticipate what in the wild would be night-time.  In dry, scientific language, when the cockroach was placed in an unchanging or aperiodic environment (constant temperature and illumination) its daily periodicity persisted indefinitely in the absence of external driving factors.  This is exciting.  Clearly there is an internal clock that ticks away at close to 24 hours even when kept in unvarying conditions, such as constant darkness.

It is not quite a 24 hour cycle, more like 24.5 hours in the cockroach, so in total darkness the cockroach would start its subjective day a half hour later each day.  This drift is similar to a grandfather clock that runs a bit slow or fast and needs readjusting.  Released from the obvious light/dark cycle that mimics the daily sunrise and sunset, the animal free runs with a natural period slightly longer than the solar cycle.  The free running rhythm is synchronised each day and forced (entrained) by light exactly to the 24 hour solar cycle.  For most organisms, light is the main time-giver that keeps the mechanism synchronised to dawn and dusk.

The cockroach clock displays all the key characteristics of all circadian rhythms.  They show a free running rhythm under constant conditions with a period that is close to but not exactly 24 hours; the free running rhythm can be entrained to exactly 24 hours by an environmental time giver and the rhythm, like all good clocks, is temperature compensated.  Likewise the endogenous circannual clock shows similar characteristics.  Under certain conditions, it has a period that is close to a year and will free run.  It is entrained by an environmental time giver such as the day length and it seems in most cases to be temperature compensated

The source of the experience

Foster and Kreitzmann

Concepts, symbols and science items

Symbols

Science Items

Activities and commonsteps

Activities

Commonsteps

References