In their book, Why We Get Sick, Drs. Randolph Neese and George Williams10 address the question of anxiety’s greater evolutionary purpose. As discussed earlier, the anxiety system serves as a fight-or-flight system, designed for our protection. In an interesting experiment, guppies were placed in a tank with a smallmouth bass behind a glass separating pane. The experimenters categorized the guppies into three different classes based on their confrontation with the big fish: timid (hid), ordinary (swam away), and bold (eyed the bass).
When the glass pane separating the groups was removed and sixty hours passed, 40% of the timid group were alive, while only 13% of the normal group and none of the bold group were alive (those not alive were eaten by the smallmouth bass). This is one of many examples that illustrates how anxiety—like a fire alarm designed to save a life once even if causing a hundred false alarms—protects us. From this point of view, it might be that we do not sufficiently fear certain elements of the modern world, such as nuclear radiation or firearms.
Common phobias—of leaving home,flying, driving, receiving group attention, or being trapped in a closed space—all stem from situations which, evolutionarily, would have been quite precarious (being eaten if away from the group, falling from a high place, high speed reminiscent of a predator’s attack, being punished, or being trapped in a cave).
In another animal model of anxiety, infant monkeys separated from their mothers become acutely anxious and agitated in an attempt to get their mother’s attention. This model is useful in terms of thinking about anxiety as a means of protecting us from separation.
The anxious monkeys in this example try to soothe themselves as well as to bring themselves back into their mothers’ attention. These animal models teach us of anxiety’s adaptive purposes.