Cybernetics and the environment
We have seen that feedback applies in technological systems and systems involving animals - it also applies to the environment - a complex set of interacting systems. There are interactions between different species, for instance, predator - prey systems, but also so called mutualistic systems where two species help each other.
In fact, the Earth itself comprises feedback loops. This is illustrated by the Gaia hypothesis, postulated by James Lovelock, a former Visiting Professor to Cybernetics at Reading. At its strongest, the Gaia hypothesis states that the Earth is a self regulating cybernetic systems, with feedback loops aimed at controlling temperature, the amount of oxygen, salinity of the sea, etc.
This it does as a result of feedback in which life and the planet work together to their mutual advantage, producing conditions suitable for both Earth and the life on it. This concept was at first dismissed by many biologists who believed that life adapted to its environment. To demonstrate how life and the planet could interact, Lovelock produced a simple model, Daisyworld.
Daisyworld is a grey planet orbiting a sun which is heating up (like our own). In the soil are seeds of daisies which grow between 7 and 37 degrees, but grow best at 22 degrees. Initially the planet is too cold, but once it becomes warm enough, daisies grow and keep the temperature constant for a long period at 22 degrees. This happens due to feedback.
If the temperature is below the optimum, more black daisies grow, absorbing heat and heating the surrounding area. If the temperature is above the optimum, white daisies thrive which reflect heat away, thereby cooling the surrounding area.
Once again, a feedback system, with two opposite control actions, either heating or cooling the planet.