Thalpos-Mental Health

Does Depression serve an evolutionary function?

  • Published on:
    22/11/2016
Does Depression serve an evolutionary function?

By the Psychologist of "Thalpos Attica" Maria Makridaki

Evolutionary psychology combines the modern principles of psychology with the core principles of evolutionary Darwinian biology (Buss, 2009). Millions of years of evolution have provided specific environmental challenges which have resulted in specific cognitive mechanisms designed to meet those challenges, explaining that our minds and their information-processing mechanisms are just as much products of the evolutionary process as our bodies. (Siegert & Ward, 2002). This recent turn in psychology has led to evolutionary explanations being sought for an increasing number of pervasive aspects of human thought and feelings (Barkow et al., 1987; Buss, 1995).

People experiencing depression become inactive, lose their appetite, their sexual drive and even their will and motivation to live and all these go against the primary functions necessary to survive and procreate. However, is it possible that depression, in spite of its apparent costs, has an evolutionary function? Two relevant theories regarding depressed mood follow.

Depression as energy storing

The theory of energy/resources conservation explains that low levels of energy and loss of appetite associated with depression, are likely to be adaptive in the sense that they allow the individual to conserve energy and later redirect it towards more productive endeavors (Allen & Badcock, 2003). Nesse (2000) explains that depressed mood acts us an adaptive response by adjusting resource allocation (e.g., energy) to hinder investments in poor pay-off activities.

Social Competition Theory: depression as a de-escalating strategy

Another framework, the social competition theory, expands on a central evolutionary assertion that an individual's access to reproductive resources will vary according to his or her rank, within the wider social group (Buss, 1999). Humans strive to acquire higher status through competition. The losing contestant of this competition will adopt a de-escalating strategy, characterized by subordinate or yielding behavior (Price, 1998). This strategy represents a withdrawal from the fight, reducing the risk of physical incapacity or death by sending 'no-threat’ signals to deactivate the aggressive behavior of the attacker (Price, 1984). Thus, depression is conceptualized as an evolved, involuntary de-escalating strategy which enables the individual to acknowledge defeat in ritual agonistic encounters, and adapt to the resulting loss in social rank (Price et al., 1994).

In our effort to understand and explain a case of depression, we can look to the person’s developmental history for vulnerability factors, we can examine the person’s current cognitions for depression-related schemas, or we might attribute the person’s depression to serotonin imbalance. All these approaches have their value in explaining certain causal aspects of this person’s experience. However, only evolutionary causes explain ‘why’ humans become depressed in the first place (Siegert & Ward, 2002).

Gilbert (1998) explains that according to the evolutionary perspective, there is less need to hold up some ideal standard of rational thinking as the norm. Less need to perceive for instance the thoughts of a person experiencing depression as irrational, distorted, and inadequate. Rather, such cognitions can be normalized so as to reduce one’s existing feelings of failure, inadequacy, self-blame and unworthiness. However, at the same time, it needs to be clearly stated that a tendency toward such thinking, although normal in its origins, is self-defeating in the current environment because of its very prolonged, very intense, and very pervasive nature.

References
  • Allen N.B. and Badcock, P.B.T. (2003).The social risk hypothesis of depressed mood: evolutionary, psychosocial, and neurobiological perspectives, Psychology Bulletin 129, (6), 887–913.
  • Barkow, J.H., Cosmides, L. and Tooby, J., 1987. The Adapted Mind, NY: Oxford   University Press.
  • Buss, D.M., (1995). Evolutionary psychology: a new paradigm for psychological science. Psychological Inquiry, 6, 1–30.
  • Buss, D.M. (1999). Evolutionary psychology: the new science of the mind. New York: Allyn & Bacon.
  • Gilbert, P. (1998). The evolved basis and adaptive functions of cognitive distortions. British Journal of Medical Psychology, 71,.447–463.
  • Nesse, R.M. (2000). Is depression an adaptation?, Archives of  General Psychiatry 57 (2000), 14–20.
  • Price, J. (1984). The evolutionary model of psychiatric disorder, Archives of General Psychiatry 41 (1984), 211.
  • Price, J.S., Sloman, L., Gardner, R., Gilbert P., and Rohde, R. (1994).The social competition hypothesis of depression, British Journal of Psychiatry 164, 309–315.
  • Price, J. (1998). The adaptive function of mood change, British Journal of Medical Psychology 71, 465–477.
  • Siegert, R.J. and Ward, T. (2002). Clinical Psychology and Evolutionary Psychology: Toward a Dialogue. Review of General Psychology, 6(3), 235-259.