In our opinion, the secondary metabolites produced by plants are products of their evolutionary process, and humans evolving alongside these compounds grew accustomed to the effects of these compounds on the human body.
Additionally, when looking at many of the prominent issues affecting modern society, it is reasonable to conclude that a deficiency in terpenes can contribute to a greater tendency toward homeostatic disruptions.
Though the extent is still unknown, it is reasonable to assume that humans lack a component for successfully adapting to elements of life in cities. After all, the sudden absence of a group of compounds found widely in their environment since pre-historic times can be expected to have side effects, one of which is outlined below.
Increased Risk for Stress
Stress causes the body to enter a mode characterized by physiological changes and cortisol release. This was effective for the occasional fight-or-flight response when humans were threatened by predators and assailants. However, this response is misappropriated in modern society where it can occur at any point during a stressful day and can become chronic.
Is it possible that a lack of terpenes in what we could call one's 'Respiratory Diet' might lead to increased stress? We believe so.