The ability to adapt to a changing environment is an essential characteristic of living organisms and social systems. Higher organisms are usually capable of three types of adaptation that come into play in succession during prolonged environmental changes. A person moving from a place at sea level to a place at a high altitude may begin to gasp and suffer from tachycardia. These changes are easily reversible: if the same day the person descends to a lower place again, the changes will disappear immediately. These kinds of adaptation changes are part of the stress phenomenon, which consists of taking one or more variables of the organism to their extreme values. As a result of that, The whole system will become rigid with respect to these variables and therefore will be unable to adapt to a new stress. For example, the person who has climbed to a high altitude will not be able to run up the stairs. Furthermore, since all the variables in the system are related to each other, the stiffness of one of them will affect the others, and the loss of flexibility will extend to the entire system.
If environmental change persists, the organism will go through a new adaptation process. The more stable components of the system will undergo a series of complex physiological changes in order to absorb environmental impact and restore flexibility. Thus, the person at a high altitude will be able to breathe normally again after a certain period of time and use the gasping mechanism to adapt to other emergencies that could be fatal. This form of adaptation is known as somatic change. Acclimatization, habit building, and addiction are special cases of this process.
Through somatic change, the body recovers part of its flexibility, substituting a more profound and lasting change for a more superficial and reversible change. This adaptation will be achieved very slowly, as will also be your return to the previous situation. Despite this, the somatic changes remain reversible. This means that, in order for you to revert to the previous situation, several circuits of the biological system must be available for the entire time the change is maintained. Excessive duration of circuit loading will limit the body’s freedom to control other functions and consequently reduce its flexibility. Although the system is more flexible after somatic change than before, when in a state of tension, it is still less flexible than before the original anxiety arose. For this reason, somatic change turns change inward, and the accumulation of this internal tension can, in the long run, lead to illness.
The third type of adaptation that living beings have is the adaptation of species in the process of evolution. The changes brought about by mutations, so-called genotypic changes, are completely different from somatic changes. Through genotypic change, a species can adapt to the environment, modifying the scope of some variables, and in particular those that give rise to the most economical changes. For example, when the weather gets colder, an animal, instead of running around to stay warm, will develop a thicker coat. Genotypic change is much more flexible than somatic change. Since each cell contains a copy of the new genetic information, it will behave in the new way and for this it will not need to receive any messages from the surrounding tissues and organs. In this way there will be more free circuits and the flexibility of the assembly will increase. On the other hand, the genotypic change is irreversible in the life of the organism.