Evolutionary psychology: Anxiety and depression

What is Anxiety

Anxiety in itself is not a pathological response of the organism, rather a normal reaction to potentially dangerous situations. Anxiety becomes pathological, however, when its levels become excessive and persistent.

A certain level of anxiety is present in all of us and it manifests itself in specific situations, such as a job interview, in order to maintain the body vigilant. Anxiety is therefore a useful reaction because it prepares us to face the outcome of a specific situation.

It is important to underline the specificity of anxiety disorders, because the stimuli that may or may nor be considered dangerous or anxiety-provoking, are subjective to the individual. This is why there are various types of anxiety disorders that range anywhere from generalized anxiety to specific (i.e. phobias).

The Biological Prospective

The biological approach to understanding anxiety focuses on researching the possible malfunctioning of cerebral processes that underlay the disorder.

In the attempt to explain the foundation of phobias, for instance, biological research points in two directions:

  • Genetic Factors: Ost (1992) and Kegan and Snidman (1991) have found a certain degree of familiarity among patients with specific phobias and their closest relatives. For example, the fear of blood is 64% more probable among relatives than it is among non related individuals in the rest of the general population.
  • Autonomous Nervous System: This theory focuses on a possible hypersensitivity of the autonomous nervous system, because it is here that the body reacts to fear and anxiety. Lacey (1967) indicates that some individuals may be more prone to a hyperactivity of the systems that regulate the physiological responses to fear. This hyperactivity, in turn, may be genetically predetermined (Gabbay, 1992).

The Evolutionary Prospective

Stemming from the evolutionary assumption that all modern psychiatric illnesses have an evolutionary significance to the species, anxiety is seen as an adaptive response that was selected specifically for its survival and reproductive values.

Seen in this light, one might ask why, if anxiety is so useful, we are not anxious all the time. Baron-Cohen (1997) responds to this question by placing the focus of attention on the physical effects of anxiety. If these are excessive, they are dangerous to the body. If the body were in constant anxious mode, the calories and energies burned by the individual would eventually create the counterproductive effect of damaging the tissues. Anxiety, therefore, is a costly response that, for this very reason, is only activated in situations of real necessity.

Generalized Anxiety is seen by evolutionary psychologists as a response that evolved out of necessity when individuals faced ambiguous dangers. In this frame, the reactions activated by the brain would have had the specific function of placing the individual in a state of vigilance in order to react, and survive, if danger were to arise. The anxiety we all feel when we are facing new and unexplored situations or events could be therefore explained as a hereditary behavioral response that evolved through our ancestors.

In applying this theory to modern anxiety disorders, it can be hypothesized that the symptoms experienced by anxious individuals are correct responses that are not functioning properly. In other words, they are activated in a context that does not represent a real, objective danger.

What is Depression

Evolutionary psychology rotates around the principle that the behaviors we manifest today are a result of survival mechanisms that our species developed throughout evolution. Based on this theory, abnormal behavior is seen as the malfunctioning of mechanisms that once increased the fitness of our species.

There are behaviors that are universally shared by all humans, despite cultural and ethnic differences. Facial expressions and fight-or-flight responses are just two of the many genetically inherited behaviors that our species developed through time and that survive today because they increased the chances of survival for the species itself. But can abnormal psychology be explained in the same terms? Can a pathological process that brings disadvantage to the individual be seen as an ancient adaptive response to the environment?

Evolutionary Roots of Depression

According to David Buss (1999), psychiatric illnesses develop when one of the evolutionary mechanisms our species developed through time is activated in an environment for which it was not projected. This can happen in three different ways:

  • The mechanism is activated in inappropriate contexts.
  • The mechanism is not activated when necessary.
  • The mechanism cannot coordinate adequately with others.

At first glance, depression does not seem to be in any way useful to our species, but according to evolutionary psychologists such as Baron-Cohen (1997), our ancestors with a predisposition to depression must have survived at a better rate than those that were not predisposed.

Theory of Involuntary Submission

According to McGuire and Raleigh (1983), vervet monkeys possess a cerebral mechanism that connects their mood to social status. In their studies, the researchers found that dominant male monkeys had double the levels of serotonin in their brain compared to all the other males in the group, and that the loss of social status would immediately halve those levels and provoke behaviors of withdrawal and loss of appetite.

In applying this theory to the human species, Price and Sloman (1987) have advanced the possibility that depression could be seen as a behavioral strategy used by losing members of a group in a hierarchical struggle. In these terms, depression is seen as a strategy used by an individual to signal submission to the leader and to protect himself from physical harm.

Price and Sloman believe that this strategy, in humans, is displayed in three ways:

  • Inhibition of aggressive behavior: diminishes the probability of attack by the dominant member
  • Submission: informs the rival that there is no threat, and signals supporters that the individual has no intention to react
  • Acceptance: submission encourages the individual to accept the loss of the competition. This process brings reconciliation and the end of the conflict.

Does Evolutionary Psychology Explain Depression

Evolutionary theories of depression may need further research. However explained, depression remains a pathological illness that is difficult to frame as an adaptive strategy that allowed our ancestors to better survive.

The level of distress depression causes may lead us to the assumption, instead, that a response mechanism that was once efficient in resolving a specific survival problem is malfunctioning today. Keeping these considerations in mind, our knowledge of the disease may be increased if accompanied by more recent biological and psychiatric studies.

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