Diseases with an Evolutionary Meaning
The homeostatic model points to disease as a physiological failure, an error or breakdown that prevents the organism from functioning properly. However, this model has shortcomings in explaining why this error occurs, and these are at the root of why we are unable to correct degenerative diseases such as diabetes, blood pressure or Alzheimer’s, even though we are well aware of their causes.
The allostatic or integrative model, on the other hand, does not see disease as an organic failure, but as a process. Until it reaches organ failure—which would be the last part of the process—every step the organism takes is adaptive and makes sense. The problem lies in the sum of these adaptations in wrong directions. Let’s look at this in more detail with the example of hypertension:
- Blood pressure varies continuously during the course of the day, to cope with expected changes in demand.
- If, during the day, we continuously experience situations that activate the body or require high blood pressure, as in cases of chronic stress, the body adapts to the new conditions.
- The daily blood pressure values increase, because the body expects that these values will be required more frequently. Gradually and adaptively, we raise our blood pressure values.
- As high blood pressure persists, the body adapts. Artery walls thicken, narrowing the space through which blood circulates, making even more blood pressure necessary to maintain blood flow. Arteries become “addicted” to high blood pressure, in a feedback loop that keeps raising the pressure.
Hypertension is attributed to a damage, something “broken”. However, nothing is broken. It is an adaptation that becomes chronic because of our lifestyle. Each step, in isolation, made sense.
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From the book:📚The Nature of Training.